AWSKMS

The service configuration used to instantiate this service client.

Returns the singleton service client. If the singleton object does not exist, the SDK instantiates the default service client with defaultServiceConfiguration from [AWSServiceManager defaultServiceManager]. The reference to this object is maintained by the SDK, and you do not need to retain it manually.

For example, set the default service configuration in - application:didFinishLaunchingWithOptions:

Swift

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
   let credentialProvider = AWSCognitoCredentialsProvider(regionType: .USEast1, identityPoolId: "YourIdentityPoolId")
   let configuration = AWSServiceConfiguration(region: .USEast1, credentialsProvider: credentialProvider)
   AWSServiceManager.default().defaultServiceConfiguration = configuration

   return true

}

Objective-C

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
     AWSCognitoCredentialsProvider *credentialsProvider = [[AWSCognitoCredentialsProvider alloc] initWithRegionType:AWSRegionUSEast1
                                                                                                     identityPoolId:@"YourIdentityPoolId"];
     AWSServiceConfiguration *configuration = [[AWSServiceConfiguration alloc] initWithRegion:AWSRegionUSEast1
                                                                          credentialsProvider:credentialsProvider];
     [AWSServiceManager defaultServiceManager].defaultServiceConfiguration = configuration;

     return YES;
 }

Then call the following to get the default service client:

Swift

let KMS = AWSKMS.default()

Objective-C

AWSKMS *KMS = [AWSKMS defaultKMS];

Creates a service client with the given service configuration and registers it for the key.

For example, set the default service configuration in - application:didFinishLaunchingWithOptions:

Swift

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
   let credentialProvider = AWSCognitoCredentialsProvider(regionType: .USEast1, identityPoolId: "YourIdentityPoolId")
   let configuration = AWSServiceConfiguration(region: .USWest2, credentialsProvider: credentialProvider)
   AWSKMS.register(with: configuration!, forKey: "USWest2KMS")

   return true

}

Objective-C

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    AWSCognitoCredentialsProvider *credentialsProvider = [[AWSCognitoCredentialsProvider alloc] initWithRegionType:AWSRegionUSEast1
                                                                                                    identityPoolId:@"YourIdentityPoolId"];
    AWSServiceConfiguration *configuration = [[AWSServiceConfiguration alloc] initWithRegion:AWSRegionUSWest2
                                                                         credentialsProvider:credentialsProvider];

    [AWSKMS registerKMSWithConfiguration:configuration forKey:@"USWest2KMS"];

    return YES;
}

Then call the following to get the service client:

Swift

let KMS = AWSKMS(forKey: "USWest2KMS")

Objective-C

AWSKMS *KMS = [AWSKMS KMSForKey:@"USWest2KMS"];

Retrieves the service client associated with the key. You need to call + registerKMSWithConfiguration:forKey: before invoking this method.

For example, set the default service configuration in - application:didFinishLaunchingWithOptions:

Swift

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
   let credentialProvider = AWSCognitoCredentialsProvider(regionType: .USEast1, identityPoolId: "YourIdentityPoolId")
   let configuration = AWSServiceConfiguration(region: .USWest2, credentialsProvider: credentialProvider)
   AWSKMS.register(with: configuration!, forKey: "USWest2KMS")

   return true

}

Objective-C

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    AWSCognitoCredentialsProvider *credentialsProvider = [[AWSCognitoCredentialsProvider alloc] initWithRegionType:AWSRegionUSEast1
                                                                                                    identityPoolId:@"YourIdentityPoolId"];
    AWSServiceConfiguration *configuration = [[AWSServiceConfiguration alloc] initWithRegion:AWSRegionUSWest2
                                                                         credentialsProvider:credentialsProvider];

    [AWSKMS registerKMSWithConfiguration:configuration forKey:@"USWest2KMS"];

    return YES;
}

Then call the following to get the service client:

Swift

let KMS = AWSKMS(forKey: "USWest2KMS")

Objective-C

AWSKMS *KMS = [AWSKMS KMSForKey:@"USWest2KMS"];

Removes the service client associated with the key and release it.

Cancels the deletion of a customer master key (CMK). When this operation succeeds, the key state of the CMK is Disabled. To enable the CMK, use EnableKey.

For more information about scheduling and canceling deletion of a CMK, see Deleting Customer Master Keys in the AWS Key Management Service Developer Guide.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a CMK in a different AWS account.

Required permissions: kms:CancelKeyDeletion (key policy)

Related operations: ScheduleKeyDeletion

Cancels the deletion of a customer master key (CMK). When this operation succeeds, the key state of the CMK is Disabled. To enable the CMK, use EnableKey.

For more information about scheduling and canceling deletion of a CMK, see Deleting Customer Master Keys in the AWS Key Management Service Developer Guide.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a CMK in a different AWS account.

Required permissions: kms:CancelKeyDeletion (key policy)

Related operations: ScheduleKeyDeletion

Connects or reconnects a custom key store to its associated AWS CloudHSM cluster.

The custom key store must be connected before you can create customer master keys (CMKs) in the key store or use the CMKs it contains. You can disconnect and reconnect a custom key store at any time.

To connect a custom key store, its associated AWS CloudHSM cluster must have at least one active HSM. To get the number of active HSMs in a cluster, use the DescribeClusters operation. To add HSMs to the cluster, use the CreateHsm operation. Also, the kmsuser crypto user (CU) must not be logged into the cluster. This prevents AWS KMS from using this account to log in.

The connection process can take an extended amount of time to complete; up to 20 minutes. This operation starts the connection process, but it does not wait for it to complete. When it succeeds, this operation quickly returns an HTTP 200 response and a JSON object with no properties. However, this response does not indicate that the custom key store is connected. To get the connection state of the custom key store, use the DescribeCustomKeyStores operation.

During the connection process, AWS KMS finds the AWS CloudHSM cluster that is associated with the custom key store, creates the connection infrastructure, connects to the cluster, logs into the AWS CloudHSM client as the kmsuser CU, and rotates its password.

The ConnectCustomKeyStore operation might fail for various reasons. To find the reason, use the DescribeCustomKeyStores operation and see the ConnectionErrorCode in the response. For help interpreting the ConnectionErrorCode, see CustomKeyStoresListEntry.

To fix the failure, use the DisconnectCustomKeyStore operation to disconnect the custom key store, correct the error, use the UpdateCustomKeyStore operation if necessary, and then use ConnectCustomKeyStore again.

If you are having trouble connecting or disconnecting a custom key store, see Troubleshooting a Custom Key Store in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a custom key store in a different AWS account.

Required permissions: kms:ConnectCustomKeyStore (IAM policy)

Related operations

• CreateCustomKeyStore

• DeleteCustomKeyStore

• DescribeCustomKeyStores

• DisconnectCustomKeyStore

• UpdateCustomKeyStore

Connects or reconnects a custom key store to its associated AWS CloudHSM cluster.

The custom key store must be connected before you can create customer master keys (CMKs) in the key store or use the CMKs it contains. You can disconnect and reconnect a custom key store at any time.

To connect a custom key store, its associated AWS CloudHSM cluster must have at least one active HSM. To get the number of active HSMs in a cluster, use the DescribeClusters operation. To add HSMs to the cluster, use the CreateHsm operation. Also, the kmsuser crypto user (CU) must not be logged into the cluster. This prevents AWS KMS from using this account to log in.

The connection process can take an extended amount of time to complete; up to 20 minutes. This operation starts the connection process, but it does not wait for it to complete. When it succeeds, this operation quickly returns an HTTP 200 response and a JSON object with no properties. However, this response does not indicate that the custom key store is connected. To get the connection state of the custom key store, use the DescribeCustomKeyStores operation.

During the connection process, AWS KMS finds the AWS CloudHSM cluster that is associated with the custom key store, creates the connection infrastructure, connects to the cluster, logs into the AWS CloudHSM client as the kmsuser CU, and rotates its password.

The ConnectCustomKeyStore operation might fail for various reasons. To find the reason, use the DescribeCustomKeyStores operation and see the ConnectionErrorCode in the response. For help interpreting the ConnectionErrorCode, see CustomKeyStoresListEntry.

To fix the failure, use the DisconnectCustomKeyStore operation to disconnect the custom key store, correct the error, use the UpdateCustomKeyStore operation if necessary, and then use ConnectCustomKeyStore again.

If you are having trouble connecting or disconnecting a custom key store, see Troubleshooting a Custom Key Store in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a custom key store in a different AWS account.

Required permissions: kms:ConnectCustomKeyStore (IAM policy)

Related operations

• CreateCustomKeyStore

• DeleteCustomKeyStore

• DescribeCustomKeyStores

• DisconnectCustomKeyStore

• UpdateCustomKeyStore

Creates a friendly name for a customer master key (CMK). You can use an alias to identify a CMK in the AWS KMS console, in the DescribeKey operation and in cryptographic operations, such as Encrypt and GenerateDataKey.

You can also change the CMK that’s associated with the alias (UpdateAlias) or delete the alias (DeleteAlias) at any time. These operations don’t affect the underlying CMK.

You can associate the alias with any customer managed CMK in the same AWS Region. Each alias is associated with only on CMK at a time, but a CMK can have multiple aliases. A valid CMK is required. You can’t create an alias without a CMK.

The alias must be unique in the account and Region, but you can have aliases with the same name in different Regions. For detailed information about aliases, see Using aliases in the AWS Key Management Service Developer Guide.

This operation does not return a response. To get the alias that you created, use the ListAliases operation.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on an alias in a different AWS account.

Required permissions

• kms:CreateAlias on the alias (IAM policy).

• kms:CreateAlias on the CMK (key policy).

For details, see Controlling access to aliases in the AWS Key Management Service Developer Guide.

Related operations:

• DeleteAlias

• ListAliases

• UpdateAlias

Creates a friendly name for a customer master key (CMK). You can use an alias to identify a CMK in the AWS KMS console, in the DescribeKey operation and in cryptographic operations, such as Encrypt and GenerateDataKey.

You can also change the CMK that’s associated with the alias (UpdateAlias) or delete the alias (DeleteAlias) at any time. These operations don’t affect the underlying CMK.

You can associate the alias with any customer managed CMK in the same AWS Region. Each alias is associated with only on CMK at a time, but a CMK can have multiple aliases. A valid CMK is required. You can’t create an alias without a CMK.

The alias must be unique in the account and Region, but you can have aliases with the same name in different Regions. For detailed information about aliases, see Using aliases in the AWS Key Management Service Developer Guide.

This operation does not return a response. To get the alias that you created, use the ListAliases operation.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on an alias in a different AWS account.

Required permissions

• kms:CreateAlias on the alias (IAM policy).

• kms:CreateAlias on the CMK (key policy).

For details, see Controlling access to aliases in the AWS Key Management Service Developer Guide.

Related operations:

• DeleteAlias

• ListAliases

• UpdateAlias

Creates a custom key store that is associated with an AWS CloudHSM cluster that you own and manage.

This operation is part of the Custom Key Store feature feature in AWS KMS, which combines the convenience and extensive integration of AWS KMS with the isolation and control of a single-tenant key store.

Before you create the custom key store, you must assemble the required elements, including an AWS CloudHSM cluster that fulfills the requirements for a custom key store. For details about the required elements, see Assemble the Prerequisites in the AWS Key Management Service Developer Guide.

When the operation completes successfully, it returns the ID of the new custom key store. Before you can use your new custom key store, you need to use the ConnectCustomKeyStore operation to connect the new key store to its AWS CloudHSM cluster. Even if you are not going to use your custom key store immediately, you might want to connect it to verify that all settings are correct and then disconnect it until you are ready to use it.

For help with failures, see Troubleshooting a Custom Key Store in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a custom key store in a different AWS account.

Required permissions: kms:CreateCustomKeyStore (IAM policy).

Related operations:

• ConnectCustomKeyStore

• DeleteCustomKeyStore

• DescribeCustomKeyStores

• DisconnectCustomKeyStore

• UpdateCustomKeyStore

Creates a custom key store that is associated with an AWS CloudHSM cluster that you own and manage.

This operation is part of the Custom Key Store feature feature in AWS KMS, which combines the convenience and extensive integration of AWS KMS with the isolation and control of a single-tenant key store.

Before you create the custom key store, you must assemble the required elements, including an AWS CloudHSM cluster that fulfills the requirements for a custom key store. For details about the required elements, see Assemble the Prerequisites in the AWS Key Management Service Developer Guide.

When the operation completes successfully, it returns the ID of the new custom key store. Before you can use your new custom key store, you need to use the ConnectCustomKeyStore operation to connect the new key store to its AWS CloudHSM cluster. Even if you are not going to use your custom key store immediately, you might want to connect it to verify that all settings are correct and then disconnect it until you are ready to use it.

For help with failures, see Troubleshooting a Custom Key Store in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a custom key store in a different AWS account.

Required permissions: kms:CreateCustomKeyStore (IAM policy).

Related operations:

• ConnectCustomKeyStore

• DeleteCustomKeyStore

• DescribeCustomKeyStores

• DisconnectCustomKeyStore

• UpdateCustomKeyStore

Adds a grant to a customer master key (CMK). The grant allows the grantee principal to use the CMK when the conditions specified in the grant are met. When setting permissions, grants are an alternative to key policies.

To create a grant that allows a cryptographic operation only when the request includes a particular encryption context, use the Constraints parameter. For details, see GrantConstraints.

You can create grants on symmetric and asymmetric CMKs. However, if the grant allows an operation that the CMK does not support, CreateGrant fails with a ValidationException.

• Grants for symmetric CMKs cannot allow operations that are not supported for symmetric CMKs, including Sign, Verify, and GetPublicKey. (There are limited exceptions to this rule for legacy operations, but you should not create a grant for an operation that AWS KMS does not support.)

• Grants for asymmetric CMKs cannot allow operations that are not supported for asymmetric CMKs, including operations that generate data keys or data key pairs, or operations related to automatic key rotation, imported key material, or CMKs in custom key stores.

• Grants for asymmetric CMKs with a KeyUsage of ENCRYPT_DECRYPT cannot allow the Sign or Verify operations. Grants for asymmetric CMKs with a KeyUsage of SIGN_VERIFY cannot allow the Encrypt or Decrypt operations.

• Grants for asymmetric CMKs cannot include an encryption context grant constraint. An encryption context is not supported on asymmetric CMKs.

For information about symmetric and asymmetric CMKs, see Using Symmetric and Asymmetric CMKs in the AWS Key Management Service Developer Guide. For more information about grants, see Grants in the AWS Key Management Service Developer Guide.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: Yes. To perform this operation on a CMK in a different AWS account, specify the key ARN in the value of the KeyId parameter.

Required permissions: kms:CreateGrant (key policy)

Related operations:

• ListGrants

• ListRetirableGrants

• RetireGrant

• RevokeGrant

Adds a grant to a customer master key (CMK). The grant allows the grantee principal to use the CMK when the conditions specified in the grant are met. When setting permissions, grants are an alternative to key policies.

To create a grant that allows a cryptographic operation only when the request includes a particular encryption context, use the Constraints parameter. For details, see GrantConstraints.

You can create grants on symmetric and asymmetric CMKs. However, if the grant allows an operation that the CMK does not support, CreateGrant fails with a ValidationException.

• Grants for symmetric CMKs cannot allow operations that are not supported for symmetric CMKs, including Sign, Verify, and GetPublicKey. (There are limited exceptions to this rule for legacy operations, but you should not create a grant for an operation that AWS KMS does not support.)

• Grants for asymmetric CMKs cannot allow operations that are not supported for asymmetric CMKs, including operations that generate data keys or data key pairs, or operations related to automatic key rotation, imported key material, or CMKs in custom key stores.

• Grants for asymmetric CMKs with a KeyUsage of ENCRYPT_DECRYPT cannot allow the Sign or Verify operations. Grants for asymmetric CMKs with a KeyUsage of SIGN_VERIFY cannot allow the Encrypt or Decrypt operations.

• Grants for asymmetric CMKs cannot include an encryption context grant constraint. An encryption context is not supported on asymmetric CMKs.

For information about symmetric and asymmetric CMKs, see Using Symmetric and Asymmetric CMKs in the AWS Key Management Service Developer Guide. For more information about grants, see Grants in the AWS Key Management Service Developer Guide.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: Yes. To perform this operation on a CMK in a different AWS account, specify the key ARN in the value of the KeyId parameter.

Required permissions: kms:CreateGrant (key policy)

Related operations:

• ListGrants

• ListRetirableGrants

• RetireGrant

• RevokeGrant

Creates a unique customer managed customer master key (CMK) in your AWS account and Region.

You can use the CreateKey operation to create symmetric or asymmetric CMKs.

• Symmetric CMKs contain a 256-bit symmetric key that never leaves AWS KMS unencrypted. To use the CMK, you must call AWS KMS. You can use a symmetric CMK to encrypt and decrypt small amounts of data, but they are typically used to generate data keys and data keys pairs. For details, see GenerateDataKey and GenerateDataKeyPair.

• Asymmetric CMKs can contain an RSA key pair or an Elliptic Curve (ECC) key pair. The private key in an asymmetric CMK never leaves AWS KMS unencrypted. However, you can use the GetPublicKey operation to download the public key so it can be used outside of AWS KMS. CMKs with RSA key pairs can be used to encrypt or decrypt data or sign and verify messages (but not both). CMKs with ECC key pairs can be used only to sign and verify messages.

For information about symmetric and asymmetric CMKs, see Using Symmetric and Asymmetric CMKs in the AWS Key Management Service Developer Guide.

To create different types of CMKs, use the following guidance:

Asymmetric CMKs

To create an asymmetric CMK, use the CustomerMasterKeySpec parameter to specify the type of key material in the CMK. Then, use the KeyUsage parameter to determine whether the CMK will be used to encrypt and decrypt or sign and verify. You can’t change these properties after the CMK is created.

Symmetric CMKs

When creating a symmetric CMK, you don’t need to specify the CustomerMasterKeySpec or KeyUsage parameters. The default value for CustomerMasterKeySpec, SYMMETRIC_DEFAULT, and the default value for KeyUsage, ENCRYPT_DECRYPT, are the only valid values for symmetric CMKs.

Imported Key Material

To import your own key material, begin by creating a symmetric CMK with no key material. To do this, use the Origin parameter of CreateKey with a value of EXTERNAL. Next, use GetParametersForImport operation to get a public key and import token, and use the public key to encrypt your key material. Then, use ImportKeyMaterial with your import token to import the key material. For step-by-step instructions, see Importing Key Material in the AWS Key Management Service Developer Guide. You cannot import the key material into an asymmetric CMK.

Custom Key Stores

To create a symmetric CMK in a custom key store, use the CustomKeyStoreId parameter to specify the custom key store. You must also use the Origin parameter with a value of AWS_CLOUDHSM. The AWS CloudHSM cluster that is associated with the custom key store must have at least two active HSMs in different Availability Zones in the AWS Region.

You cannot create an asymmetric CMK in a custom key store. For information about custom key stores in AWS KMS see Using Custom Key Stores in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot use this operation to create a CMK in a different AWS account.

Required permissions: kms:CreateKey (IAM policy). To use the Tags parameter, kms:TagResource (IAM policy). For examples and information about related permissions, see Allow a user to create CMKs in the AWS Key Management Service Developer Guide.

Related operations:

• DescribeKey

• ListKeys

• ScheduleKeyDeletion

Creates a unique customer managed customer master key (CMK) in your AWS account and Region.

You can use the CreateKey operation to create symmetric or asymmetric CMKs.

• Symmetric CMKs contain a 256-bit symmetric key that never leaves AWS KMS unencrypted. To use the CMK, you must call AWS KMS. You can use a symmetric CMK to encrypt and decrypt small amounts of data, but they are typically used to generate data keys and data keys pairs. For details, see GenerateDataKey and GenerateDataKeyPair.

• Asymmetric CMKs can contain an RSA key pair or an Elliptic Curve (ECC) key pair. The private key in an asymmetric CMK never leaves AWS KMS unencrypted. However, you can use the GetPublicKey operation to download the public key so it can be used outside of AWS KMS. CMKs with RSA key pairs can be used to encrypt or decrypt data or sign and verify messages (but not both). CMKs with ECC key pairs can be used only to sign and verify messages.

For information about symmetric and asymmetric CMKs, see Using Symmetric and Asymmetric CMKs in the AWS Key Management Service Developer Guide.

To create different types of CMKs, use the following guidance:

Asymmetric CMKs

To create an asymmetric CMK, use the CustomerMasterKeySpec parameter to specify the type of key material in the CMK. Then, use the KeyUsage parameter to determine whether the CMK will be used to encrypt and decrypt or sign and verify. You can’t change these properties after the CMK is created.

Symmetric CMKs

When creating a symmetric CMK, you don’t need to specify the CustomerMasterKeySpec or KeyUsage parameters. The default value for CustomerMasterKeySpec, SYMMETRIC_DEFAULT, and the default value for KeyUsage, ENCRYPT_DECRYPT, are the only valid values for symmetric CMKs.

Imported Key Material

To import your own key material, begin by creating a symmetric CMK with no key material. To do this, use the Origin parameter of CreateKey with a value of EXTERNAL. Next, use GetParametersForImport operation to get a public key and import token, and use the public key to encrypt your key material. Then, use ImportKeyMaterial with your import token to import the key material. For step-by-step instructions, see Importing Key Material in the AWS Key Management Service Developer Guide. You cannot import the key material into an asymmetric CMK.

Custom Key Stores

To create a symmetric CMK in a custom key store, use the CustomKeyStoreId parameter to specify the custom key store. You must also use the Origin parameter with a value of AWS_CLOUDHSM. The AWS CloudHSM cluster that is associated with the custom key store must have at least two active HSMs in different Availability Zones in the AWS Region.

You cannot create an asymmetric CMK in a custom key store. For information about custom key stores in AWS KMS see Using Custom Key Stores in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot use this operation to create a CMK in a different AWS account.

Required permissions: kms:CreateKey (IAM policy). To use the Tags parameter, kms:TagResource (IAM policy). For examples and information about related permissions, see Allow a user to create CMKs in the AWS Key Management Service Developer Guide.

Related operations:

• DescribeKey

• ListKeys

• ScheduleKeyDeletion

Decrypts ciphertext that was encrypted by a AWS KMS customer master key (CMK) using any of the following operations:

• Encrypt

• GenerateDataKey

• GenerateDataKeyPair

• GenerateDataKeyWithoutPlaintext

• GenerateDataKeyPairWithoutPlaintext

You can use this operation to decrypt ciphertext that was encrypted under a symmetric or asymmetric CMK. When the CMK is asymmetric, you must specify the CMK and the encryption algorithm that was used to encrypt the ciphertext. For information about symmetric and asymmetric CMKs, see Using Symmetric and Asymmetric CMKs in the AWS Key Management Service Developer Guide.

The Decrypt operation also decrypts ciphertext that was encrypted outside of AWS KMS by the public key in an AWS KMS asymmetric CMK. However, it cannot decrypt ciphertext produced by other libraries, such as the AWS Encryption SDK or Amazon S3 client-side encryption. These libraries return a ciphertext format that is incompatible with AWS KMS.

If the ciphertext was encrypted under a symmetric CMK, the KeyId parameter is optional. AWS KMS can get this information from metadata that it adds to the symmetric ciphertext blob. This feature adds durability to your implementation by ensuring that authorized users can decrypt ciphertext decades after it was encrypted, even if they’ve lost track of the CMK ID. However, specifying the CMK is always recommended as a best practice. When you use the KeyId parameter to specify a CMK, AWS KMS only uses the CMK you specify. If the ciphertext was encrypted under a different CMK, the Decrypt operation fails. This practice ensures that you use the CMK that you intend.

Whenever possible, use key policies to give users permission to call the Decrypt operation on a particular CMK, instead of using IAM policies. Otherwise, you might create an IAM user policy that gives the user Decrypt permission on all CMKs. This user could decrypt ciphertext that was encrypted by CMKs in other accounts if the key policy for the cross-account CMK permits it. If you must use an IAM policy for Decrypt permissions, limit the user to particular CMKs or particular trusted accounts. For details, see Best practices for IAM policies in the AWS Key Management Service Developer Guide.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: Yes. You can decrypt a ciphertext using a CMK in a different AWS account.

Required permissions: kms:Decrypt (key policy)

Related operations:

• Encrypt

• GenerateDataKey

• GenerateDataKeyPair

• ReEncrypt

Decrypts ciphertext that was encrypted by a AWS KMS customer master key (CMK) using any of the following operations:

• Encrypt

• GenerateDataKey

• GenerateDataKeyPair

• GenerateDataKeyWithoutPlaintext

• GenerateDataKeyPairWithoutPlaintext

You can use this operation to decrypt ciphertext that was encrypted under a symmetric or asymmetric CMK. When the CMK is asymmetric, you must specify the CMK and the encryption algorithm that was used to encrypt the ciphertext. For information about symmetric and asymmetric CMKs, see Using Symmetric and Asymmetric CMKs in the AWS Key Management Service Developer Guide.

The Decrypt operation also decrypts ciphertext that was encrypted outside of AWS KMS by the public key in an AWS KMS asymmetric CMK. However, it cannot decrypt ciphertext produced by other libraries, such as the AWS Encryption SDK or Amazon S3 client-side encryption. These libraries return a ciphertext format that is incompatible with AWS KMS.

If the ciphertext was encrypted under a symmetric CMK, the KeyId parameter is optional. AWS KMS can get this information from metadata that it adds to the symmetric ciphertext blob. This feature adds durability to your implementation by ensuring that authorized users can decrypt ciphertext decades after it was encrypted, even if they’ve lost track of the CMK ID. However, specifying the CMK is always recommended as a best practice. When you use the KeyId parameter to specify a CMK, AWS KMS only uses the CMK you specify. If the ciphertext was encrypted under a different CMK, the Decrypt operation fails. This practice ensures that you use the CMK that you intend.

Whenever possible, use key policies to give users permission to call the Decrypt operation on a particular CMK, instead of using IAM policies. Otherwise, you might create an IAM user policy that gives the user Decrypt permission on all CMKs. This user could decrypt ciphertext that was encrypted by CMKs in other accounts if the key policy for the cross-account CMK permits it. If you must use an IAM policy for Decrypt permissions, limit the user to particular CMKs or particular trusted accounts. For details, see Best practices for IAM policies in the AWS Key Management Service Developer Guide.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: Yes. You can decrypt a ciphertext using a CMK in a different AWS account.

Required permissions: kms:Decrypt (key policy)

Related operations:

• Encrypt

• GenerateDataKey

• GenerateDataKeyPair

• ReEncrypt

Deletes the specified alias.

Because an alias is not a property of a CMK, you can delete and change the aliases of a CMK without affecting the CMK. Also, aliases do not appear in the response from the DescribeKey operation. To get the aliases of all CMKs, use the ListAliases operation.

Each CMK can have multiple aliases. To change the alias of a CMK, use DeleteAlias to delete the current alias and CreateAlias to create a new alias. To associate an existing alias with a different customer master key (CMK), call UpdateAlias.

Cross-account use: No. You cannot perform this operation on an alias in a different AWS account.

Required permissions

• kms:DeleteAlias on the alias (IAM policy).

• kms:DeleteAlias on the CMK (key policy).

For details, see Controlling access to aliases in the AWS Key Management Service Developer Guide.

Related operations:

• CreateAlias

• ListAliases

• UpdateAlias

Deletes the specified alias.

Because an alias is not a property of a CMK, you can delete and change the aliases of a CMK without affecting the CMK. Also, aliases do not appear in the response from the DescribeKey operation. To get the aliases of all CMKs, use the ListAliases operation.

Each CMK can have multiple aliases. To change the alias of a CMK, use DeleteAlias to delete the current alias and CreateAlias to create a new alias. To associate an existing alias with a different customer master key (CMK), call UpdateAlias.

Cross-account use: No. You cannot perform this operation on an alias in a different AWS account.

Required permissions

• kms:DeleteAlias on the alias (IAM policy).

• kms:DeleteAlias on the CMK (key policy).

For details, see Controlling access to aliases in the AWS Key Management Service Developer Guide.

Related operations:

• CreateAlias

• ListAliases

• UpdateAlias

Deletes a custom key store. This operation does not delete the AWS CloudHSM cluster that is associated with the custom key store, or affect any users or keys in the cluster.

The custom key store that you delete cannot contain any AWS KMS customer master keys (CMKs). Before deleting the key store, verify that you will never need to use any of the CMKs in the key store for any cryptographic operations. Then, use ScheduleKeyDeletion to delete the AWS KMS customer master keys (CMKs) from the key store. When the scheduled waiting period expires, the ScheduleKeyDeletion operation deletes the CMKs. Then it makes a best effort to delete the key material from the associated cluster. However, you might need to manually delete the orphaned key material from the cluster and its backups.

After all CMKs are deleted from AWS KMS, use DisconnectCustomKeyStore to disconnect the key store from AWS KMS. Then, you can delete the custom key store.

Instead of deleting the custom key store, consider using DisconnectCustomKeyStore to disconnect it from AWS KMS. While the key store is disconnected, you cannot create or use the CMKs in the key store. But, you do not need to delete CMKs and you can reconnect a disconnected custom key store at any time.

If the operation succeeds, it returns a JSON object with no properties.

This operation is part of the Custom Key Store feature feature in AWS KMS, which combines the convenience and extensive integration of AWS KMS with the isolation and control of a single-tenant key store.

Cross-account use: No. You cannot perform this operation on a custom key store in a different AWS account.

Required permissions: kms:DeleteCustomKeyStore (IAM policy)

Related operations:

• ConnectCustomKeyStore

• CreateCustomKeyStore

• DescribeCustomKeyStores

• DisconnectCustomKeyStore

• UpdateCustomKeyStore

Deletes a custom key store. This operation does not delete the AWS CloudHSM cluster that is associated with the custom key store, or affect any users or keys in the cluster.

The custom key store that you delete cannot contain any AWS KMS customer master keys (CMKs). Before deleting the key store, verify that you will never need to use any of the CMKs in the key store for any cryptographic operations. Then, use ScheduleKeyDeletion to delete the AWS KMS customer master keys (CMKs) from the key store. When the scheduled waiting period expires, the ScheduleKeyDeletion operation deletes the CMKs. Then it makes a best effort to delete the key material from the associated cluster. However, you might need to manually delete the orphaned key material from the cluster and its backups.

After all CMKs are deleted from AWS KMS, use DisconnectCustomKeyStore to disconnect the key store from AWS KMS. Then, you can delete the custom key store.

Instead of deleting the custom key store, consider using DisconnectCustomKeyStore to disconnect it from AWS KMS. While the key store is disconnected, you cannot create or use the CMKs in the key store. But, you do not need to delete CMKs and you can reconnect a disconnected custom key store at any time.

If the operation succeeds, it returns a JSON object with no properties.

This operation is part of the Custom Key Store feature feature in AWS KMS, which combines the convenience and extensive integration of AWS KMS with the isolation and control of a single-tenant key store.

Cross-account use: No. You cannot perform this operation on a custom key store in a different AWS account.

Required permissions: kms:DeleteCustomKeyStore (IAM policy)

Related operations:

• ConnectCustomKeyStore

• CreateCustomKeyStore

• DescribeCustomKeyStores

• DisconnectCustomKeyStore

• UpdateCustomKeyStore

Deletes key material that you previously imported. This operation makes the specified customer master key (CMK) unusable. For more information about importing key material into AWS KMS, see Importing Key Material in the AWS Key Management Service Developer Guide.

When the specified CMK is in the PendingDeletion state, this operation does not change the CMK’s state. Otherwise, it changes the CMK’s state to PendingImport.

After you delete key material, you can use ImportKeyMaterial to reimport the same key material into the CMK.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a CMK in a different AWS account.

Required permissions: kms:DeleteImportedKeyMaterial (key policy)

Related operations:

• GetParametersForImport

• ImportKeyMaterial

Deletes key material that you previously imported. This operation makes the specified customer master key (CMK) unusable. For more information about importing key material into AWS KMS, see Importing Key Material in the AWS Key Management Service Developer Guide.

When the specified CMK is in the PendingDeletion state, this operation does not change the CMK’s state. Otherwise, it changes the CMK’s state to PendingImport.

After you delete key material, you can use ImportKeyMaterial to reimport the same key material into the CMK.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a CMK in a different AWS account.

Required permissions: kms:DeleteImportedKeyMaterial (key policy)

Related operations:

• GetParametersForImport

• ImportKeyMaterial

Gets information about custom key stores in the account and region.

This operation is part of the Custom Key Store feature feature in AWS KMS, which combines the convenience and extensive integration of AWS KMS with the isolation and control of a single-tenant key store.

By default, this operation returns information about all custom key stores in the account and region. To get only information about a particular custom key store, use either the CustomKeyStoreName or CustomKeyStoreId parameter (but not both).

To determine whether the custom key store is connected to its AWS CloudHSM cluster, use the ConnectionState element in the response. If an attempt to connect the custom key store failed, the ConnectionState value is FAILED and the ConnectionErrorCode element in the response indicates the cause of the failure. For help interpreting the ConnectionErrorCode, see CustomKeyStoresListEntry.

Custom key stores have a DISCONNECTED connection state if the key store has never been connected or you use the DisconnectCustomKeyStore operation to disconnect it. If your custom key store state is CONNECTED but you are having trouble using it, make sure that its associated AWS CloudHSM cluster is active and contains the minimum number of HSMs required for the operation, if any.

For help repairing your custom key store, see the Troubleshooting Custom Key Stores topic in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a custom key store in a different AWS account.

Required permissions: kms:DescribeCustomKeyStores (IAM policy)

Related operations:

• ConnectCustomKeyStore

• CreateCustomKeyStore

• DeleteCustomKeyStore

• DisconnectCustomKeyStore

• UpdateCustomKeyStore

Gets information about custom key stores in the account and region.

This operation is part of the Custom Key Store feature feature in AWS KMS, which combines the convenience and extensive integration of AWS KMS with the isolation and control of a single-tenant key store.

By default, this operation returns information about all custom key stores in the account and region. To get only information about a particular custom key store, use either the CustomKeyStoreName or CustomKeyStoreId parameter (but not both).

To determine whether the custom key store is connected to its AWS CloudHSM cluster, use the ConnectionState element in the response. If an attempt to connect the custom key store failed, the ConnectionState value is FAILED and the ConnectionErrorCode element in the response indicates the cause of the failure. For help interpreting the ConnectionErrorCode, see CustomKeyStoresListEntry.

Custom key stores have a DISCONNECTED connection state if the key store has never been connected or you use the DisconnectCustomKeyStore operation to disconnect it. If your custom key store state is CONNECTED but you are having trouble using it, make sure that its associated AWS CloudHSM cluster is active and contains the minimum number of HSMs required for the operation, if any.

For help repairing your custom key store, see the Troubleshooting Custom Key Stores topic in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a custom key store in a different AWS account.

Required permissions: kms:DescribeCustomKeyStores (IAM policy)

Related operations:

• ConnectCustomKeyStore

• CreateCustomKeyStore

• DeleteCustomKeyStore

• DisconnectCustomKeyStore

• UpdateCustomKeyStore

Provides detailed information about a customer master key (CMK). You can run DescribeKey on a customer managed CMK or an AWS managed CMK.

This detailed information includes the key ARN, creation date (and deletion date, if applicable), the key state, and the origin and expiration date (if any) of the key material. For CMKs in custom key stores, it includes information about the custom key store, such as the key store ID and the AWS CloudHSM cluster ID. It includes fields, like KeySpec, that help you distinguish symmetric from asymmetric CMKs. It also provides information that is particularly important to asymmetric CMKs, such as the key usage (encryption or signing) and the encryption algorithms or signing algorithms that the CMK supports.

DescribeKey does not return the following information:

• Aliases associated with the CMK. To get this information, use ListAliases.

• Whether automatic key rotation is enabled on the CMK. To get this information, use GetKeyRotationStatus. Also, some key states prevent a CMK from being automatically rotated. For details, see How Automatic Key Rotation Works in AWS Key Management Service Developer Guide.

• Tags on the CMK. To get this information, use ListResourceTags.

• Key policies and grants on the CMK. To get this information, use GetKeyPolicy and ListGrants.

If you call the DescribeKey operation on a predefined AWS alias, that is, an AWS alias with no key ID, AWS KMS creates an AWS managed CMK. Then, it associates the alias with the new CMK, and returns the KeyId and Arn of the new CMK in the response.

Cross-account use: Yes. To perform this operation with a CMK in a different AWS account, specify the key ARN or alias ARN in the value of the KeyId parameter.

Required permissions: kms:DescribeKey (key policy)

Related operations:

• GetKeyPolicy

• GetKeyRotationStatus

• ListAliases

• ListGrants

• ListKeys

• ListResourceTags

• ListRetirableGrants

Provides detailed information about a customer master key (CMK). You can run DescribeKey on a customer managed CMK or an AWS managed CMK.

This detailed information includes the key ARN, creation date (and deletion date, if applicable), the key state, and the origin and expiration date (if any) of the key material. For CMKs in custom key stores, it includes information about the custom key store, such as the key store ID and the AWS CloudHSM cluster ID. It includes fields, like KeySpec, that help you distinguish symmetric from asymmetric CMKs. It also provides information that is particularly important to asymmetric CMKs, such as the key usage (encryption or signing) and the encryption algorithms or signing algorithms that the CMK supports.

DescribeKey does not return the following information:

• Aliases associated with the CMK. To get this information, use ListAliases.

• Whether automatic key rotation is enabled on the CMK. To get this information, use GetKeyRotationStatus. Also, some key states prevent a CMK from being automatically rotated. For details, see How Automatic Key Rotation Works in AWS Key Management Service Developer Guide.

• Tags on the CMK. To get this information, use ListResourceTags.

• Key policies and grants on the CMK. To get this information, use GetKeyPolicy and ListGrants.

If you call the DescribeKey operation on a predefined AWS alias, that is, an AWS alias with no key ID, AWS KMS creates an AWS managed CMK. Then, it associates the alias with the new CMK, and returns the KeyId and Arn of the new CMK in the response.

Cross-account use: Yes. To perform this operation with a CMK in a different AWS account, specify the key ARN or alias ARN in the value of the KeyId parameter.

Required permissions: kms:DescribeKey (key policy)

Related operations:

• GetKeyPolicy

• GetKeyRotationStatus

• ListAliases

• ListGrants

• ListKeys

• ListResourceTags

• ListRetirableGrants

Sets the state of a customer master key (CMK) to disabled. This change temporarily prevents use of the CMK for cryptographic operations.

For more information about how key state affects the use of a CMK, see How Key State Affects the Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a CMK in a different AWS account.

Required permissions: kms:DisableKey (key policy)

Related operations: EnableKey

Sets the state of a customer master key (CMK) to disabled. This change temporarily prevents use of the CMK for cryptographic operations.

For more information about how key state affects the use of a CMK, see How Key State Affects the Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a CMK in a different AWS account.

Required permissions: kms:DisableKey (key policy)

Related operations: EnableKey

Disables automatic rotation of the key material for the specified symmetric customer master key (CMK).

You cannot enable automatic rotation of asymmetric CMKs, CMKs with imported key material, or CMKs in a custom key store.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a CMK in a different AWS account.

Required permissions: kms:DisableKeyRotation (key policy)

Related operations:

• EnableKeyRotation

• GetKeyRotationStatus

Disables automatic rotation of the key material for the specified symmetric customer master key (CMK).

You cannot enable automatic rotation of asymmetric CMKs, CMKs with imported key material, or CMKs in a custom key store.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a CMK in a different AWS account.

Required permissions: kms:DisableKeyRotation (key policy)

Related operations:

• EnableKeyRotation

• GetKeyRotationStatus

Disconnects the custom key store from its associated AWS CloudHSM cluster. While a custom key store is disconnected, you can manage the custom key store and its customer master keys (CMKs), but you cannot create or use CMKs in the custom key store. You can reconnect the custom key store at any time.

To find the connection state of a custom key store, use the DescribeCustomKeyStores operation. To reconnect a custom key store, use the ConnectCustomKeyStore operation.

If the operation succeeds, it returns a JSON object with no properties.

This operation is part of the Custom Key Store feature feature in AWS KMS, which combines the convenience and extensive integration of AWS KMS with the isolation and control of a single-tenant key store.

Cross-account use: No. You cannot perform this operation on a custom key store in a different AWS account.

Required permissions: kms:DisconnectCustomKeyStore (IAM policy)

Related operations:

• ConnectCustomKeyStore

• CreateCustomKeyStore

• DeleteCustomKeyStore

• DescribeCustomKeyStores

• UpdateCustomKeyStore

Disconnects the custom key store from its associated AWS CloudHSM cluster. While a custom key store is disconnected, you can manage the custom key store and its customer master keys (CMKs), but you cannot create or use CMKs in the custom key store. You can reconnect the custom key store at any time.

To find the connection state of a custom key store, use the DescribeCustomKeyStores operation. To reconnect a custom key store, use the ConnectCustomKeyStore operation.

If the operation succeeds, it returns a JSON object with no properties.

This operation is part of the Custom Key Store feature feature in AWS KMS, which combines the convenience and extensive integration of AWS KMS with the isolation and control of a single-tenant key store.

Cross-account use: No. You cannot perform this operation on a custom key store in a different AWS account.

Required permissions: kms:DisconnectCustomKeyStore (IAM policy)

Related operations:

• ConnectCustomKeyStore

• CreateCustomKeyStore

• DeleteCustomKeyStore

• DescribeCustomKeyStores

• UpdateCustomKeyStore

Sets the key state of a customer master key (CMK) to enabled. This allows you to use the CMK for cryptographic operations.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a CMK in a different AWS account.

Required permissions: kms:EnableKey (key policy)

Related operations: DisableKey

Sets the key state of a customer master key (CMK) to enabled. This allows you to use the CMK for cryptographic operations.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a CMK in a different AWS account.

Required permissions: kms:EnableKey (key policy)

Related operations: DisableKey

Enables automatic rotation of the key material for the specified symmetric customer master key (CMK).

You cannot enable automatic rotation of asymmetric CMKs, CMKs with imported key material, or CMKs in a custom key store.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a CMK in a different AWS account.

Required permissions: kms:EnableKeyRotation (key policy)

Related operations:

• DisableKeyRotation

• GetKeyRotationStatus

Enables automatic rotation of the key material for the specified symmetric customer master key (CMK).

You cannot enable automatic rotation of asymmetric CMKs, CMKs with imported key material, or CMKs in a custom key store.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a CMK in a different AWS account.

Required permissions: kms:EnableKeyRotation (key policy)

Related operations:

• DisableKeyRotation

• GetKeyRotationStatus

Encrypts plaintext into ciphertext by using a customer master key (CMK). The Encrypt operation has two primary use cases:

• You can encrypt small amounts of arbitrary data, such as a personal identifier or database password, or other sensitive information.

• You can use the Encrypt operation to move encrypted data from one AWS Region to another. For example, in Region A, generate a data key and use the plaintext key to encrypt your data. Then, in Region A, use the Encrypt operation to encrypt the plaintext data key under a CMK in Region B. Now, you can move the encrypted data and the encrypted data key to Region B. When necessary, you can decrypt the encrypted data key and the encrypted data entirely within in Region B.

You don’t need to use the Encrypt operation to encrypt a data key. The GenerateDataKey and GenerateDataKeyPair operations return a plaintext data key and an encrypted copy of that data key.

When you encrypt data, you must specify a symmetric or asymmetric CMK to use in the encryption operation. The CMK must have a KeyUsage value of ENCRYPT_DECRYPT. To find the KeyUsage of a CMK, use the DescribeKey operation.

If you use a symmetric CMK, you can use an encryption context to add additional security to your encryption operation. If you specify an EncryptionContext when encrypting data, you must specify the same encryption context (a case-sensitive exact match) when decrypting the data. Otherwise, the request to decrypt fails with an InvalidCiphertextException. For more information, see Encryption Context in the AWS Key Management Service Developer Guide.

If you specify an asymmetric CMK, you must also specify the encryption algorithm. The algorithm must be compatible with the CMK type.

The maximum size of the data that you can encrypt varies with the type of CMK and the encryption algorithm that you choose.

• Symmetric CMKs

  • SYMMETRIC_DEFAULT: 4096 bytes

• RSA_2048

  • RSAES_OAEP_SHA_1: 214 bytes

  • RSAES_OAEP_SHA_256: 190 bytes

• RSA_3072

  • RSAES_OAEP_SHA_1: 342 bytes

  • RSAES_OAEP_SHA_256: 318 bytes

• RSA_4096

  • RSAES_OAEP_SHA_1: 470 bytes

  • RSAES_OAEP_SHA_256: 446 bytes

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: Yes. To perform this operation with a CMK in a different AWS account, specify the key ARN or alias ARN in the value of the KeyId parameter.

Required permissions: kms:Encrypt (key policy)

Related operations:

• Decrypt

• GenerateDataKey

• GenerateDataKeyPair

Encrypts plaintext into ciphertext by using a customer master key (CMK). The Encrypt operation has two primary use cases:

• You can encrypt small amounts of arbitrary data, such as a personal identifier or database password, or other sensitive information.

• You can use the Encrypt operation to move encrypted data from one AWS Region to another. For example, in Region A, generate a data key and use the plaintext key to encrypt your data. Then, in Region A, use the Encrypt operation to encrypt the plaintext data key under a CMK in Region B. Now, you can move the encrypted data and the encrypted data key to Region B. When necessary, you can decrypt the encrypted data key and the encrypted data entirely within in Region B.

You don’t need to use the Encrypt operation to encrypt a data key. The GenerateDataKey and GenerateDataKeyPair operations return a plaintext data key and an encrypted copy of that data key.

When you encrypt data, you must specify a symmetric or asymmetric CMK to use in the encryption operation. The CMK must have a KeyUsage value of ENCRYPT_DECRYPT. To find the KeyUsage of a CMK, use the DescribeKey operation.

If you use a symmetric CMK, you can use an encryption context to add additional security to your encryption operation. If you specify an EncryptionContext when encrypting data, you must specify the same encryption context (a case-sensitive exact match) when decrypting the data. Otherwise, the request to decrypt fails with an InvalidCiphertextException. For more information, see Encryption Context in the AWS Key Management Service Developer Guide.

If you specify an asymmetric CMK, you must also specify the encryption algorithm. The algorithm must be compatible with the CMK type.

The maximum size of the data that you can encrypt varies with the type of CMK and the encryption algorithm that you choose.

• Symmetric CMKs

  • SYMMETRIC_DEFAULT: 4096 bytes

• RSA_2048

  • RSAES_OAEP_SHA_1: 214 bytes

  • RSAES_OAEP_SHA_256: 190 bytes

• RSA_3072

  • RSAES_OAEP_SHA_1: 342 bytes

  • RSAES_OAEP_SHA_256: 318 bytes

• RSA_4096

  • RSAES_OAEP_SHA_1: 470 bytes

  • RSAES_OAEP_SHA_256: 446 bytes

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: Yes. To perform this operation with a CMK in a different AWS account, specify the key ARN or alias ARN in the value of the KeyId parameter.

Required permissions: kms:Encrypt (key policy)

Related operations:

• Decrypt

• GenerateDataKey

• GenerateDataKeyPair

Generates a unique symmetric data key for client-side encryption. This operation returns a plaintext copy of the data key and a copy that is encrypted under a customer master key (CMK) that you specify. You can use the plaintext key to encrypt your data outside of AWS KMS and store the encrypted data key with the encrypted data.

GenerateDataKey returns a unique data key for each request. The bytes in the plaintext key are not related to the caller or the CMK.

To generate a data key, specify the symmetric CMK that will be used to encrypt the data key. You cannot use an asymmetric CMK to generate data keys. To get the type of your CMK, use the DescribeKey operation. You must also specify the length of the data key. Use either the KeySpec or NumberOfBytes parameters (but not both). For 128-bit and 256-bit data keys, use the KeySpec parameter.

To get only an encrypted copy of the data key, use GenerateDataKeyWithoutPlaintext. To generate an asymmetric data key pair, use the GenerateDataKeyPair or GenerateDataKeyPairWithoutPlaintext operation. To get a cryptographically secure random byte string, use GenerateRandom.

You can use the optional encryption context to add additional security to the encryption operation. If you specify an EncryptionContext, you must specify the same encryption context (a case-sensitive exact match) when decrypting the encrypted data key. Otherwise, the request to decrypt fails with an InvalidCiphertextException. For more information, see Encryption Context in the AWS Key Management Service Developer Guide.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

How to use your data key

We recommend that you use the following pattern to encrypt data locally in your application. You can write your own code or use a client-side encryption library, such as the AWS Encryption SDK, the Amazon DynamoDB Encryption Client, or Amazon S3 client-side encryption to do these tasks for you.

To encrypt data outside of AWS KMS:

1. Use the GenerateDataKey operation to get a data key.

2. Use the plaintext data key (in the Plaintext field of the response) to encrypt your data outside of AWS KMS. Then erase the plaintext data key from memory.

3. Store the encrypted data key (in the CiphertextBlob field of the response) with the encrypted data.

To decrypt data outside of AWS KMS:

1. Use the Decrypt operation to decrypt the encrypted data key. The operation returns a plaintext copy of the data key.

2. Use the plaintext data key to decrypt data outside of AWS KMS, then erase the plaintext data key from memory.

Cross-account use: Yes. To perform this operation with a CMK in a different AWS account, specify the key ARN or alias ARN in the value of the KeyId parameter.

Required permissions: kms:GenerateDataKey (key policy)

Related operations:

• Decrypt

• Encrypt

• GenerateDataKeyPair

• GenerateDataKeyPairWithoutPlaintext

• GenerateDataKeyWithoutPlaintext

Generates a unique symmetric data key for client-side encryption. This operation returns a plaintext copy of the data key and a copy that is encrypted under a customer master key (CMK) that you specify. You can use the plaintext key to encrypt your data outside of AWS KMS and store the encrypted data key with the encrypted data.

GenerateDataKey returns a unique data key for each request. The bytes in the plaintext key are not related to the caller or the CMK.

To generate a data key, specify the symmetric CMK that will be used to encrypt the data key. You cannot use an asymmetric CMK to generate data keys. To get the type of your CMK, use the DescribeKey operation. You must also specify the length of the data key. Use either the KeySpec or NumberOfBytes parameters (but not both). For 128-bit and 256-bit data keys, use the KeySpec parameter.

To get only an encrypted copy of the data key, use GenerateDataKeyWithoutPlaintext. To generate an asymmetric data key pair, use the GenerateDataKeyPair or GenerateDataKeyPairWithoutPlaintext operation. To get a cryptographically secure random byte string, use GenerateRandom.

You can use the optional encryption context to add additional security to the encryption operation. If you specify an EncryptionContext, you must specify the same encryption context (a case-sensitive exact match) when decrypting the encrypted data key. Otherwise, the request to decrypt fails with an InvalidCiphertextException. For more information, see Encryption Context in the AWS Key Management Service Developer Guide.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

How to use your data key

We recommend that you use the following pattern to encrypt data locally in your application. You can write your own code or use a client-side encryption library, such as the AWS Encryption SDK, the Amazon DynamoDB Encryption Client, or Amazon S3 client-side encryption to do these tasks for you.

To encrypt data outside of AWS KMS:

1. Use the GenerateDataKey operation to get a data key.

2. Use the plaintext data key (in the Plaintext field of the response) to encrypt your data outside of AWS KMS. Then erase the plaintext data key from memory.

3. Store the encrypted data key (in the CiphertextBlob field of the response) with the encrypted data.

To decrypt data outside of AWS KMS:

1. Use the Decrypt operation to decrypt the encrypted data key. The operation returns a plaintext copy of the data key.

2. Use the plaintext data key to decrypt data outside of AWS KMS, then erase the plaintext data key from memory.

Cross-account use: Yes. To perform this operation with a CMK in a different AWS account, specify the key ARN or alias ARN in the value of the KeyId parameter.

Required permissions: kms:GenerateDataKey (key policy)

Related operations:

• Decrypt

• Encrypt

• GenerateDataKeyPair

• GenerateDataKeyPairWithoutPlaintext

• GenerateDataKeyWithoutPlaintext

Generates a unique asymmetric data key pair. The GenerateDataKeyPair operation returns a plaintext public key, a plaintext private key, and a copy of the private key that is encrypted under the symmetric CMK you specify. You can use the data key pair to perform asymmetric cryptography outside of AWS KMS.

GenerateDataKeyPair returns a unique data key pair for each request. The bytes in the keys are not related to the caller or the CMK that is used to encrypt the private key.

You can use the public key that GenerateDataKeyPair returns to encrypt data or verify a signature outside of AWS KMS. Then, store the encrypted private key with the data. When you are ready to decrypt data or sign a message, you can use the Decrypt operation to decrypt the encrypted private key.

To generate a data key pair, you must specify a symmetric customer master key (CMK) to encrypt the private key in a data key pair. You cannot use an asymmetric CMK or a CMK in a custom key store. To get the type and origin of your CMK, use the DescribeKey operation.

If you are using the data key pair to encrypt data, or for any operation where you don’t immediately need a private key, consider using the GenerateDataKeyPairWithoutPlaintext operation. GenerateDataKeyPairWithoutPlaintext returns a plaintext public key and an encrypted private key, but omits the plaintext private key that you need only to decrypt ciphertext or sign a message. Later, when you need to decrypt the data or sign a message, use the Decrypt operation to decrypt the encrypted private key in the data key pair.

You can use the optional encryption context to add additional security to the encryption operation. If you specify an EncryptionContext, you must specify the same encryption context (a case-sensitive exact match) when decrypting the encrypted data key. Otherwise, the request to decrypt fails with an InvalidCiphertextException. For more information, see Encryption Context in the AWS Key Management Service Developer Guide.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: Yes. To perform this operation with a CMK in a different AWS account, specify the key ARN or alias ARN in the value of the KeyId parameter.

Required permissions: kms:GenerateDataKeyPair (key policy)

Related operations:

• Decrypt

• Encrypt

• GenerateDataKey

• GenerateDataKeyPairWithoutPlaintext

• GenerateDataKeyWithoutPlaintext

Generates a unique asymmetric data key pair. The GenerateDataKeyPair operation returns a plaintext public key, a plaintext private key, and a copy of the private key that is encrypted under the symmetric CMK you specify. You can use the data key pair to perform asymmetric cryptography outside of AWS KMS.

GenerateDataKeyPair returns a unique data key pair for each request. The bytes in the keys are not related to the caller or the CMK that is used to encrypt the private key.

You can use the public key that GenerateDataKeyPair returns to encrypt data or verify a signature outside of AWS KMS. Then, store the encrypted private key with the data. When you are ready to decrypt data or sign a message, you can use the Decrypt operation to decrypt the encrypted private key.

To generate a data key pair, you must specify a symmetric customer master key (CMK) to encrypt the private key in a data key pair. You cannot use an asymmetric CMK or a CMK in a custom key store. To get the type and origin of your CMK, use the DescribeKey operation.

If you are using the data key pair to encrypt data, or for any operation where you don’t immediately need a private key, consider using the GenerateDataKeyPairWithoutPlaintext operation. GenerateDataKeyPairWithoutPlaintext returns a plaintext public key and an encrypted private key, but omits the plaintext private key that you need only to decrypt ciphertext or sign a message. Later, when you need to decrypt the data or sign a message, use the Decrypt operation to decrypt the encrypted private key in the data key pair.

You can use the optional encryption context to add additional security to the encryption operation. If you specify an EncryptionContext, you must specify the same encryption context (a case-sensitive exact match) when decrypting the encrypted data key. Otherwise, the request to decrypt fails with an InvalidCiphertextException. For more information, see Encryption Context in the AWS Key Management Service Developer Guide.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: Yes. To perform this operation with a CMK in a different AWS account, specify the key ARN or alias ARN in the value of the KeyId parameter.

Required permissions: kms:GenerateDataKeyPair (key policy)

Related operations:

• Decrypt

• Encrypt

• GenerateDataKey

• GenerateDataKeyPairWithoutPlaintext

• GenerateDataKeyWithoutPlaintext

Generates a unique asymmetric data key pair. The GenerateDataKeyPairWithoutPlaintext operation returns a plaintext public key and a copy of the private key that is encrypted under the symmetric CMK you specify. Unlike GenerateDataKeyPair, this operation does not return a plaintext private key.

To generate a data key pair, you must specify a symmetric customer master key (CMK) to encrypt the private key in the data key pair. You cannot use an asymmetric CMK or a CMK in a custom key store. To get the type and origin of your CMK, use the KeySpec field in the DescribeKey response.

You can use the public key that GenerateDataKeyPairWithoutPlaintext returns to encrypt data or verify a signature outside of AWS KMS. Then, store the encrypted private key with the data. When you are ready to decrypt data or sign a message, you can use the Decrypt operation to decrypt the encrypted private key.

GenerateDataKeyPairWithoutPlaintext returns a unique data key pair for each request. The bytes in the key are not related to the caller or CMK that is used to encrypt the private key.

You can use the optional encryption context to add additional security to the encryption operation. If you specify an EncryptionContext, you must specify the same encryption context (a case-sensitive exact match) when decrypting the encrypted data key. Otherwise, the request to decrypt fails with an InvalidCiphertextException. For more information, see Encryption Context in the AWS Key Management Service Developer Guide.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: Yes. To perform this operation with a CMK in a different AWS account, specify the key ARN or alias ARN in the value of the KeyId parameter.

Required permissions: kms:GenerateDataKeyPairWithoutPlaintext (key policy)

Related operations:

• Decrypt

• Encrypt

• GenerateDataKey

• GenerateDataKeyPair

• GenerateDataKeyWithoutPlaintext

Generates a unique asymmetric data key pair. The GenerateDataKeyPairWithoutPlaintext operation returns a plaintext public key and a copy of the private key that is encrypted under the symmetric CMK you specify. Unlike GenerateDataKeyPair, this operation does not return a plaintext private key.

To generate a data key pair, you must specify a symmetric customer master key (CMK) to encrypt the private key in the data key pair. You cannot use an asymmetric CMK or a CMK in a custom key store. To get the type and origin of your CMK, use the KeySpec field in the DescribeKey response.

You can use the public key that GenerateDataKeyPairWithoutPlaintext returns to encrypt data or verify a signature outside of AWS KMS. Then, store the encrypted private key with the data. When you are ready to decrypt data or sign a message, you can use the Decrypt operation to decrypt the encrypted private key.

GenerateDataKeyPairWithoutPlaintext returns a unique data key pair for each request. The bytes in the key are not related to the caller or CMK that is used to encrypt the private key.

You can use the optional encryption context to add additional security to the encryption operation. If you specify an EncryptionContext, you must specify the same encryption context (a case-sensitive exact match) when decrypting the encrypted data key. Otherwise, the request to decrypt fails with an InvalidCiphertextException. For more information, see Encryption Context in the AWS Key Management Service Developer Guide.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: Yes. To perform this operation with a CMK in a different AWS account, specify the key ARN or alias ARN in the value of the KeyId parameter.

Required permissions: kms:GenerateDataKeyPairWithoutPlaintext (key policy)

Related operations:

• Decrypt

• Encrypt

• GenerateDataKey

• GenerateDataKeyPair

• GenerateDataKeyWithoutPlaintext

Generates a unique symmetric data key. This operation returns a data key that is encrypted under a customer master key (CMK) that you specify. To request an asymmetric data key pair, use the GenerateDataKeyPair or GenerateDataKeyPairWithoutPlaintext operations.

GenerateDataKeyWithoutPlaintext is identical to the GenerateDataKey operation except that returns only the encrypted copy of the data key. This operation is useful for systems that need to encrypt data at some point, but not immediately. When you need to encrypt the data, you call the Decrypt operation on the encrypted copy of the key.

It’s also useful in distributed systems with different levels of trust. For example, you might store encrypted data in containers. One component of your system creates new containers and stores an encrypted data key with each container. Then, a different component puts the data into the containers. That component first decrypts the data key, uses the plaintext data key to encrypt data, puts the encrypted data into the container, and then destroys the plaintext data key. In this system, the component that creates the containers never sees the plaintext data key.

GenerateDataKeyWithoutPlaintext returns a unique data key for each request. The bytes in the keys are not related to the caller or CMK that is used to encrypt the private key.

To generate a data key, you must specify the symmetric customer master key (CMK) that is used to encrypt the data key. You cannot use an asymmetric CMK to generate a data key. To get the type of your CMK, use the DescribeKey operation.

If the operation succeeds, you will find the encrypted copy of the data key in the CiphertextBlob field.

You can use the optional encryption context to add additional security to the encryption operation. If you specify an EncryptionContext, you must specify the same encryption context (a case-sensitive exact match) when decrypting the encrypted data key. Otherwise, the request to decrypt fails with an InvalidCiphertextException. For more information, see Encryption Context in the AWS Key Management Service Developer Guide.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: Yes. To perform this operation with a CMK in a different AWS account, specify the key ARN or alias ARN in the value of the KeyId parameter.

Required permissions: kms:GenerateDataKeyWithoutPlaintext (key policy)

Related operations:

• Decrypt

• Encrypt

• GenerateDataKey

• GenerateDataKeyPair

• GenerateDataKeyPairWithoutPlaintext

Generates a unique symmetric data key. This operation returns a data key that is encrypted under a customer master key (CMK) that you specify. To request an asymmetric data key pair, use the GenerateDataKeyPair or GenerateDataKeyPairWithoutPlaintext operations.

GenerateDataKeyWithoutPlaintext is identical to the GenerateDataKey operation except that returns only the encrypted copy of the data key. This operation is useful for systems that need to encrypt data at some point, but not immediately. When you need to encrypt the data, you call the Decrypt operation on the encrypted copy of the key.

It’s also useful in distributed systems with different levels of trust. For example, you might store encrypted data in containers. One component of your system creates new containers and stores an encrypted data key with each container. Then, a different component puts the data into the containers. That component first decrypts the data key, uses the plaintext data key to encrypt data, puts the encrypted data into the container, and then destroys the plaintext data key. In this system, the component that creates the containers never sees the plaintext data key.

GenerateDataKeyWithoutPlaintext returns a unique data key for each request. The bytes in the keys are not related to the caller or CMK that is used to encrypt the private key.

To generate a data key, you must specify the symmetric customer master key (CMK) that is used to encrypt the data key. You cannot use an asymmetric CMK to generate a data key. To get the type of your CMK, use the DescribeKey operation.

If the operation succeeds, you will find the encrypted copy of the data key in the CiphertextBlob field.

You can use the optional encryption context to add additional security to the encryption operation. If you specify an EncryptionContext, you must specify the same encryption context (a case-sensitive exact match) when decrypting the encrypted data key. Otherwise, the request to decrypt fails with an InvalidCiphertextException. For more information, see Encryption Context in the AWS Key Management Service Developer Guide.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: Yes. To perform this operation with a CMK in a different AWS account, specify the key ARN or alias ARN in the value of the KeyId parameter.

Required permissions: kms:GenerateDataKeyWithoutPlaintext (key policy)

Related operations:

• Decrypt

• Encrypt

• GenerateDataKey

• GenerateDataKeyPair

• GenerateDataKeyPairWithoutPlaintext

Returns a random byte string that is cryptographically secure.

By default, the random byte string is generated in AWS KMS. To generate the byte string in the AWS CloudHSM cluster that is associated with a custom key store, specify the custom key store ID.

For more information about entropy and random number generation, see the AWS Key Management Service Cryptographic Details whitepaper.

Required permissions: kms:GenerateRandom (IAM policy)

Returns a random byte string that is cryptographically secure.

By default, the random byte string is generated in AWS KMS. To generate the byte string in the AWS CloudHSM cluster that is associated with a custom key store, specify the custom key store ID.

For more information about entropy and random number generation, see the AWS Key Management Service Cryptographic Details whitepaper.

Required permissions: kms:GenerateRandom (IAM policy)

Gets a key policy attached to the specified customer master key (CMK).

Cross-account use: No. You cannot perform this operation on a CMK in a different AWS account.

Required permissions: kms:GetKeyPolicy (key policy)

Related operations: PutKeyPolicy

Gets a key policy attached to the specified customer master key (CMK).

Cross-account use: No. You cannot perform this operation on a CMK in a different AWS account.

Required permissions: kms:GetKeyPolicy (key policy)

Related operations: PutKeyPolicy

Gets a Boolean value that indicates whether automatic rotation of the key material is enabled for the specified customer master key (CMK).

You cannot enable automatic rotation of asymmetric CMKs, CMKs with imported key material, or CMKs in a custom key store. The key rotation status for these CMKs is always false.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

• Disabled: The key rotation status does not change when you disable a CMK. However, while the CMK is disabled, AWS KMS does not rotate the backing key.

• Pending deletion: While a CMK is pending deletion, its key rotation status is false and AWS KMS does not rotate the backing key. If you cancel the deletion, the original key rotation status is restored.

Cross-account use: Yes. To perform this operation on a CMK in a different AWS account, specify the key ARN in the value of the KeyId parameter.

Required permissions: kms:GetKeyRotationStatus (key policy)

Related operations:

• DisableKeyRotation

• EnableKeyRotation

Gets a Boolean value that indicates whether automatic rotation of the key material is enabled for the specified customer master key (CMK).

You cannot enable automatic rotation of asymmetric CMKs, CMKs with imported key material, or CMKs in a custom key store. The key rotation status for these CMKs is always false.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

• Disabled: The key rotation status does not change when you disable a CMK. However, while the CMK is disabled, AWS KMS does not rotate the backing key.

• Pending deletion: While a CMK is pending deletion, its key rotation status is false and AWS KMS does not rotate the backing key. If you cancel the deletion, the original key rotation status is restored.

Cross-account use: Yes. To perform this operation on a CMK in a different AWS account, specify the key ARN in the value of the KeyId parameter.

Required permissions: kms:GetKeyRotationStatus (key policy)

Related operations:

• DisableKeyRotation

• EnableKeyRotation

Returns the items you need to import key material into a symmetric, customer managed customer master key (CMK). For more information about importing key material into AWS KMS, see Importing Key Material in the AWS Key Management Service Developer Guide.

This operation returns a public key and an import token. Use the public key to encrypt the symmetric key material. Store the import token to send with a subsequent ImportKeyMaterial request.

You must specify the key ID of the symmetric CMK into which you will import key material. This CMK’s Origin must be EXTERNAL. You must also specify the wrapping algorithm and type of wrapping key (public key) that you will use to encrypt the key material. You cannot perform this operation on an asymmetric CMK or on any CMK in a different AWS account.

To import key material, you must use the public key and import token from the same response. These items are valid for 24 hours. The expiration date and time appear in the GetParametersForImport response. You cannot use an expired token in an ImportKeyMaterial request. If your key and token expire, send another GetParametersForImport request.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a CMK in a different AWS account.

Required permissions: kms:GetParametersForImport (key policy)

Related operations:

• ImportKeyMaterial

• DeleteImportedKeyMaterial

Returns the items you need to import key material into a symmetric, customer managed customer master key (CMK). For more information about importing key material into AWS KMS, see Importing Key Material in the AWS Key Management Service Developer Guide.

This operation returns a public key and an import token. Use the public key to encrypt the symmetric key material. Store the import token to send with a subsequent ImportKeyMaterial request.

You must specify the key ID of the symmetric CMK into which you will import key material. This CMK’s Origin must be EXTERNAL. You must also specify the wrapping algorithm and type of wrapping key (public key) that you will use to encrypt the key material. You cannot perform this operation on an asymmetric CMK or on any CMK in a different AWS account.

To import key material, you must use the public key and import token from the same response. These items are valid for 24 hours. The expiration date and time appear in the GetParametersForImport response. You cannot use an expired token in an ImportKeyMaterial request. If your key and token expire, send another GetParametersForImport request.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: No. You cannot perform this operation on a CMK in a different AWS account.

Required permissions: kms:GetParametersForImport (key policy)

Related operations:

• ImportKeyMaterial

• DeleteImportedKeyMaterial

Returns the public key of an asymmetric CMK. Unlike the private key of a asymmetric CMK, which never leaves AWS KMS unencrypted, callers with kms:GetPublicKey permission can download the public key of an asymmetric CMK. You can share the public key to allow others to encrypt messages and verify signatures outside of AWS KMS. For information about symmetric and asymmetric CMKs, see Using Symmetric and Asymmetric CMKs in the AWS Key Management Service Developer Guide.

You do not need to download the public key. Instead, you can use the public key within AWS KMS by calling the Encrypt, ReEncrypt, or Verify operations with the identifier of an asymmetric CMK. When you use the public key within AWS KMS, you benefit from the authentication, authorization, and logging that are part of every AWS KMS operation. You also reduce of risk of encrypting data that cannot be decrypted. These features are not effective outside of AWS KMS. For details, see Special Considerations for Downloading Public Keys.

To help you use the public key safely outside of AWS KMS, GetPublicKey returns important information about the public key in the response, including:

• CustomerMasterKeySpec: The type of key material in the public key, such as RSA_4096 or ECC_NIST_P521.

• KeyUsage: Whether the key is used for encryption or signing.

• EncryptionAlgorithms or SigningAlgorithms: A list of the encryption algorithms or the signing algorithms for the key.

Although AWS KMS cannot enforce these restrictions on external operations, it is crucial that you use this information to prevent the public key from being used improperly. For example, you can prevent a public signing key from being used encrypt data, or prevent a public key from being used with an encryption algorithm that is not supported by AWS KMS. You can also avoid errors, such as using the wrong signing algorithm in a verification operation.

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: Yes. To perform this operation with a CMK in a different AWS account, specify the key ARN or alias ARN in the value of the KeyId parameter.

Required permissions: kms:GetPublicKey (key policy)

Related operations: CreateKey