AWS SDK Version 3 for .NET
API Reference

AWS services or capabilities described in AWS Documentation may vary by region/location. Click Getting Started with Amazon AWS to see specific differences applicable to the China (Beijing) Region.

Returns a unique symmetric data key for use outside of KMS. This operation returns a data key that is encrypted under a symmetric encryption KMS key that you specify. The bytes in the key are random; they are not related to the caller or to the KMS key.

GenerateDataKeyWithoutPlaintext is identical to the GenerateDataKey operation except that it does not return a plaintext 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.

To request an asymmetric data key pair, use the GenerateDataKeyPair or GenerateDataKeyPairWithoutPlaintext operations.

To generate a data key, you must specify the symmetric encryption KMS key that is used to encrypt the data key. You cannot use an asymmetric KMS key or a key in a custom key store to generate a data key. To get the type of your KMS key, 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 generate an SM4 data key (China Regions only), specify a KeySpec value of AES_128 or NumberOfBytes value of 128. The symmetric encryption key used in China Regions to encrypt your data key is an SM4 encryption key.

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

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:GenerateDataKeyWithoutPlaintext (key policy)

Related operations:

Note:

For .NET Core this operation is only available in asynchronous form. Please refer to GenerateDataKeyWithoutPlaintextAsync.

Namespace: Amazon.KeyManagementService
Assembly: AWSSDK.KeyManagementService.dll
Version: 3.x.y.z

Syntax

C#
public virtual GenerateDataKeyWithoutPlaintextResponse GenerateDataKeyWithoutPlaintext(
         GenerateDataKeyWithoutPlaintextRequest request
)
Parameters
request
Type: Amazon.KeyManagementService.Model.GenerateDataKeyWithoutPlaintextRequest

Container for the necessary parameters to execute the GenerateDataKeyWithoutPlaintext service method.

Return Value
The response from the GenerateDataKeyWithoutPlaintext service method, as returned by KeyManagementService.

Exceptions

ExceptionCondition
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.
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. 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.

Examples

The following example generates an encrypted copy of a 256-bit symmetric data encryption key (data key). The data key is encrypted with the specified KMS key.

To generate an encrypted data key


var client = new AmazonKeyManagementServiceClient();
var response = client.GenerateDataKeyWithoutPlaintext(new GenerateDataKeyWithoutPlaintextRequest 
{
    KeyId = "alias/ExampleAlias", // The identifier of the KMS key to use to encrypt the data key. You can use the key ID or Amazon Resource Name (ARN) of the KMS key, or the name or ARN of an alias that refers to the KMS key.
    KeySpec = "AES_256" // Specifies the type of data key to return.
});

MemoryStream ciphertextBlob = response.CiphertextBlob; // The encrypted data key.
string keyId = response.KeyId; // The ARN of the KMS key that was used to encrypt the data key.

            

Version Information

.NET Framework:
Supported in: 4.5, 4.0, 3.5

See Also