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Returns a unique asymmetric data key pair for use outside of KMS. This operation returns a plaintext public key, a plaintext private key, and a copy of the private key that is encrypted under the symmetric encryption KMS key you specify. You can use the data key pair to perform asymmetric cryptography and implement digital signatures outside of KMS. The bytes in the keys are random; they are not related to the caller or to the KMS key 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 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 encryption KMS key to encrypt the private key in a data key pair. You cannot use an asymmetric KMS key or a KMS key in a custom key store. To get the type and origin of your KMS key, use the DescribeKey operation.
Use the KeyPairSpec parameter to choose an RSA or Elliptic Curve (ECC) data
key pair. In China Regions, you can also choose an SM2 data key pair. KMS recommends
that you use ECC key pairs for signing, and use RSA and SM2 key pairs for either encryption
or signing, but not both. However, KMS cannot enforce any restrictions on the use
of data key pairs outside of KMS.
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.
GenerateDataKeyPair returns a unique data key pair for each request. The bytes
in the keys are random; they are not related to the caller or the KMS key that is
used to encrypt the private key. The public key is a DER-encoded X.509 SubjectPublicKeyInfo,
as specified in RFC 5280. The private
key is a DER-encoded PKCS8 PrivateKeyInfo, as specified in RFC
5958.
GenerateDataKeyPair also supports Amazon
Web Services Nitro Enclaves, which provide an isolated compute environment in
Amazon EC2. To call GenerateDataKeyPair for an Amazon Web Services Nitro enclave,
use the Amazon
Web Services Nitro Enclaves SDK or any Amazon Web Services SDK. Use the Recipient
parameter to provide the attestation document for the enclave. GenerateDataKeyPair
returns the public data key and a copy of the private data key encrypted under the
specified KMS key, as usual. But instead of a plaintext copy of the private data key
(PrivateKeyPlaintext), the response includes a copy of the private data key
encrypted under the public key from the attestation document (CiphertextForRecipient).
For information about the interaction between KMS and Amazon Web Services Nitro Enclaves,
see How
Amazon Web Services Nitro Enclaves uses KMS in the Key Management Service Developer
Guide..
You can use an 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 Key Management Service Developer Guide.
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:GenerateDataKeyPair (key policy)
Related operations:
Eventual consistency: The KMS API follows an eventual consistency model. For more information, see KMS eventual consistency.
For .NET Core this operation is only available in asynchronous form. Please refer to GenerateDataKeyPairAsync.
Namespace: Amazon.KeyManagementService
Assembly: AWSSDK.KeyManagementService.dll
Version: 3.x.y.z
public virtual GenerateDataKeyPairResponse GenerateDataKeyPair( GenerateDataKeyPairRequest request )
Container for the necessary parameters to execute the GenerateDataKeyPair service method.
| Exception | Condition |
|---|---|
| DependencyTimeoutException | The system timed out while trying to fulfill the request. You can retry the request. |
| DisabledException | The request was rejected because the specified KMS key is not enabled. |
| DryRunOperationException | The request was rejected because the DryRun parameter was specified. |
| InvalidGrantTokenException | The request was rejected because the specified grant token is not valid. |
| InvalidKeyUsageException | The request was rejected for one of the following reasons: The KeyUsage value of the KMS key is incompatible with the API operation. The encryption algorithm or signing algorithm specified for the operation is incompatible with the type of key material in the KMS key (KeySpec). For encrypting, decrypting, re-encrypting, and generating data keys, the KeyUsage must be ENCRYPT_DECRYPT. For signing and verifying messages, the KeyUsage must be SIGN_VERIFY. For generating and verifying message authentication codes (MACs), the KeyUsage must be GENERATE_VERIFY_MAC. For deriving key agreement secrets, the KeyUsage must be KEY_AGREEMENT. To find the KeyUsage of a KMS key, use the DescribeKey operation. To find the encryption or signing algorithms supported for a particular KMS key, use the DescribeKey operation. |
| KeyUnavailableException | The request was rejected because the specified KMS key was not available. You can retry the request. |
| KMSInternalException | The request was rejected because an internal exception occurred. The request can be retried. |
| KMSInvalidStateException | The request was rejected because the state of the specified resource is not valid for this request. This exceptions means one of the following: The key state of the KMS key is not compatible with the operation. To find the key state, use the DescribeKey operation. For more information about which key states are compatible with each KMS operation, see Key states of KMS keys in the Key Management Service Developer Guide. For cryptographic operations on KMS keys in custom key stores, this exception represents a general failure with many possible causes. To identify the cause, see the error message that accompanies the exception. |
| NotFoundException | The request was rejected because the specified entity or resource could not be found. |
| UnsupportedOperationException | The request was rejected because a specified parameter is not supported or a specified resource is not valid for this operation. |
This example generates an RSA data key pair for encryption and decryption. The operation returns a plaintext public key and private key, and a copy of the private key that is encrypted under a symmetric encryption KMS key that you specify.
var client = new AmazonKeyManagementServiceClient();
var response = client.GenerateDataKeyPair(new GenerateDataKeyPairRequest
{
KeyId = "arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab", // The key ID of the symmetric encryption KMS key that encrypts the private RSA key in the data key pair.
KeyPairSpec = "RSA_3072" // The requested key spec of the RSA data key pair.
});
string keyId = response.KeyId; // The key ARN of the symmetric encryption KMS key that was used to encrypt the private key.
string keyPairSpec = response.KeyPairSpec; // The actual key spec of the RSA data key pair.
MemoryStream privateKeyCiphertextBlob = response.PrivateKeyCiphertextBlob; // The encrypted private key of the RSA data key pair.
MemoryStream privateKeyPlaintext = response.PrivateKeyPlaintext; // The plaintext private key of the RSA data key pair.
MemoryStream publicKey = response.PublicKey; // The public key (plaintext) of the RSA data key pair.
The following example includes the Recipient parameter with a signed attestation document from an AWS Nitro enclave. Instead of returning a plaintext copy of the private data key, GenerateDataKeyPair returns a copy of the private data key encrypted by the public key from the attestation document (CiphertextForRecipient). It returns the public data key (PublicKey) and a copy of private data key encrypted under the specified KMS key (PrivateKeyCiphertextBlob), as usual, but plaintext private data key field (PrivateKeyPlaintext) is null or empty.
var client = new AmazonKeyManagementServiceClient();
var response = client.GenerateDataKeyPair(new GenerateDataKeyPairRequest
{
KeyId = "arn:aws:kms:us-east-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab", // The key ID of the symmetric encryption KMS key that encrypts the private RSA key in the data key pair.
KeyPairSpec = "RSA_3072", // The requested key spec of the RSA data key pair.
Recipient = new RecipientInfo {
AttestationDocument = new MemoryStream(<attestation document>),
KeyEncryptionAlgorithm = "RSAES_OAEP_SHA_256"
} // Specifies the attestation document from the Nitro enclave and the encryption algorithm to use with the public key from the attestation document.
});
MemoryStream ciphertextForRecipient = response.CiphertextForRecipient; // The private key of the RSA data key pair encrypted by the public key from the attestation document
string keyId = response.KeyId; // The key ARN of the symmetric encryption KMS key that was used to encrypt the PrivateKeyCiphertextBlob.
string keyPairSpec = response.KeyPairSpec; // The actual key spec of the RSA data key pair.
MemoryStream privateKeyCiphertextBlob = response.PrivateKeyCiphertextBlob; // The private key of the RSA data key pair encrypted by the KMS key.
MemoryStream privateKeyPlaintext = response.PrivateKeyPlaintext; // This field is null or empty
MemoryStream publicKey = response.PublicKey; // The public key (plaintext) of the RSA data key pair.
.NET Framework:
Supported in: 4.5 and newer, 3.5