GetPublicKey (smaws-clients.Smaws_Client

val request : 
  Smaws_Lib.Context.t ->
  get_public_key_request ->
  (get_public_key_response,
    [> Smaws_Lib.Protocols.AwsJson.error
    | `DependencyTimeoutException of dependency_timeout_exception
    | `DisabledException of disabled_exception
    | `InvalidArnException of invalid_arn_exception
    | `InvalidGrantTokenException of invalid_grant_token_exception
    | `InvalidKeyUsageException of invalid_key_usage_exception
    | `KeyUnavailableException of key_unavailable_exception
    | `KMSInternalException of kms_internal_exception
    | `KMSInvalidStateException of kms_invalid_state_exception
    | `NotFoundException of not_found_exception
    | `UnsupportedOperationException of unsupported_operation_exception ])
    Stdlib.result

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

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

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

KeySpec: 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, signing, or deriving a shared secret.
EncryptionAlgorithms or SigningAlgorithms: A list of the encryption algorithms or the signing algorithms for the key.

Although 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 KMS. You can also avoid errors, such as using the wrong signing algorithm in a verification operation.

To verify a signature outside of KMS with an SM2 public key (China Regions only), you must specify the distinguishing ID. By default, KMS uses 1234567812345678 as the distinguishing ID. For more information, see Offline verification with SM2 key pairs.

The KMS key that you use for this operation must be in a compatible key state. For details, see Key states of KMS keys in the Key Management Service Developer Guide.

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

Required permissions: kms:GetPublicKey (key policy)

Related operations: CreateKey

Eventual consistency: The KMS API follows an eventual consistency model. For more information, see KMS eventual consistency.