GenerateDataKeyPair
Returns a unique asymmetric data key pair for use outside of AWS 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 AWS KMS. The bytes in the keys are random; they 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 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 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. AWS 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, AWS KMS cannot enforce any restrictions on the use of data key pairs outside of AWS 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
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
AWS 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 AWS KMS keys in the AWS Key Management Service Developer Guide.
Cross-account use: Yes. To perform this operation with a KMS key 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:
Request Syntax
{
"EncryptionContext": {
"string
" : "string
"
},
"GrantTokens": [ "string
" ],
"KeyId": "string
",
"KeyPairSpec": "string
"
}
Request Parameters
For information about the parameters that are common to all actions, see Common Parameters.
The request accepts the following data in JSON format.
In the following list, the required parameters are described first.
- KeyId
-
Specifies the symmetric encryption KMS key that encrypts the private key in the data key pair. You cannot specify 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.
To specify a KMS key, use its key ID, key ARN, alias name, or alias ARN. When using an alias name, prefix it with
"alias/"
. To specify a KMS key in a different AWS account, you must use the key ARN or alias ARN.For example:
-
Key ID:
1234abcd-12ab-34cd-56ef-1234567890ab
-
Key ARN:
arn:aws:kms:us-east-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab
-
Alias name:
alias/ExampleAlias
-
Alias ARN:
arn:aws:kms:us-east-2:111122223333:alias/ExampleAlias
To get the key ID and key ARN for a KMS key, use ListKeys or DescribeKey. To get the alias name and alias ARN, use ListAliases.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 2048.
Required: Yes
-
- KeyPairSpec
-
Determines the type of data key pair that is generated.
The AWS KMS rule that restricts the use of asymmetric RSA and SM2 KMS keys to encrypt and decrypt or to sign and verify (but not both), and the rule that permits you to use ECC KMS keys only to sign and verify, are not effective on data key pairs, which are used outside of AWS KMS. The SM2 key spec is only available in China Regions.
Type: String
Valid Values:
RSA_2048 | RSA_3072 | RSA_4096 | ECC_NIST_P256 | ECC_NIST_P384 | ECC_NIST_P521 | ECC_SECG_P256K1 | SM2
Required: Yes
- EncryptionContext
-
Specifies the encryption context that will be used when encrypting the private key in the data key pair.
Important Do not include confidential or sensitive information in this field. This field may be displayed in plaintext in CloudTrail logs and other output.
An encryption context is a collection of non-secret key-value pairs that represent additional authenticated data. When you use an encryption context to encrypt data, you must specify the same (an exact case-sensitive match) encryption context to decrypt the data. An encryption context is supported only on operations with symmetric encryption KMS keys. On operations with symmetric encryption KMS keys, an encryption context is optional, but it is strongly recommended.
For more information, see Encryption context in the AWS Key Management Service Developer Guide.
Type: String to string map
Required: No
- GrantTokens
-
A list of grant tokens.
Use a grant token when your permission to call this operation comes from a new grant that has not yet achieved eventual consistency. For more information, see Grant token and Using a grant token in the AWS Key Management Service Developer Guide.
Type: Array of strings
Array Members: Minimum number of 0 items. Maximum number of 10 items.
Length Constraints: Minimum length of 1. Maximum length of 8192.
Required: No
Response Syntax
{
"KeyId": "string",
"KeyPairSpec": "string",
"PrivateKeyCiphertextBlob": blob,
"PrivateKeyPlaintext": blob,
"PublicKey": blob
}
Response Elements
If the action is successful, the service sends back an HTTP 200 response.
The following data is returned in JSON format by the service.
- KeyId
-
The Amazon Resource Name (key ARN) of the KMS key that encrypted the private key.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 2048.
- KeyPairSpec
-
The type of data key pair that was generated.
Type: String
Valid Values:
RSA_2048 | RSA_3072 | RSA_4096 | ECC_NIST_P256 | ECC_NIST_P384 | ECC_NIST_P521 | ECC_SECG_P256K1 | SM2
- PrivateKeyCiphertextBlob
-
The encrypted copy of the private key. When you use the HTTP API or the AWS CLI, the value is Base64-encoded. Otherwise, it is not Base64-encoded.
Type: Base64-encoded binary data object
Length Constraints: Minimum length of 1. Maximum length of 6144.
- PrivateKeyPlaintext
-
The plaintext copy of the private key. When you use the HTTP API or the AWS CLI, the value is Base64-encoded. Otherwise, it is not Base64-encoded.
Type: Base64-encoded binary data object
Length Constraints: Minimum length of 1. Maximum length of 4096.
- PublicKey
-
The public key (in plaintext). When you use the HTTP API or the AWS CLI, the value is Base64-encoded. Otherwise, it is not Base64-encoded.
Type: Base64-encoded binary data object
Length Constraints: Minimum length of 1. Maximum length of 8192.
Errors
For information about the errors that are common to all actions, see Common Errors.
- DependencyTimeoutException
-
The system timed out while trying to fulfill the request. You can retry the request.
HTTP Status Code: 500
- DisabledException
-
The request was rejected because the specified KMS key is not enabled.
HTTP Status Code: 400
- InvalidGrantTokenException
-
The request was rejected because the specified grant token is not valid.
HTTP Status Code: 400
- 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 beENCRYPT_DECRYPT
. For signing and verifying messages, theKeyUsage
must beSIGN_VERIFY
. For generating and verifying message authentication codes (MACs), theKeyUsage
must beGENERATE_VERIFY_MAC
. To find theKeyUsage
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.
HTTP Status Code: 400
-
- KeyUnavailableException
-
The request was rejected because the specified KMS key was not available. You can retry the request.
HTTP Status Code: 500
- KMSInternalException
-
The request was rejected because an internal exception occurred. The request can be retried.
HTTP Status Code: 500
- 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 AWS KMS operation, see Key states of AWS KMS keys in the AWS 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.
HTTP Status Code: 400
-
- NotFoundException
-
The request was rejected because the specified entity or resource could not be found.
HTTP Status Code: 400
- UnsupportedOperationException
-
The request was rejected because a specified parameter is not supported or a specified resource is not valid for this operation.
HTTP Status Code: 400
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following: