AWS SDK Version 3 for .NET
API Reference

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Container for the parameters to the GenerateDataKey operation. Returns a data encryption key that you can use in your application to encrypt data locally.

You must specify the customer master key (CMK) under which to generate the data key. You must also specify the length of the data key using either the KeySpec or NumberOfBytes field. You must specify one field or the other, but not both. For common key lengths (128-bit and 256-bit symmetric keys), we recommend that you use KeySpec.

This operation returns a plaintext copy of the data key in the Plaintext field of the response, and an encrypted copy of the data key in the CiphertextBlob field. The data key is encrypted under the CMK specified in the KeyId field of the request.

We recommend that you use the following pattern to encrypt data locally in your application:

  1. Use this operation (GenerateDataKey) to retrieve a data encryption key.

  2. Use the plaintext data encryption key (returned in the Plaintext field of the response) to encrypt data locally, then erase the plaintext data key from memory.

  3. Store the encrypted data key (returned in the CiphertextBlob field of the response) alongside the locally encrypted data.

To decrypt data locally:

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

  2. Use the plaintext data key to decrypt data locally, then erase the plaintext data key from memory.

To return only an encrypted copy of the data key, use GenerateDataKeyWithoutPlaintext. To return a random byte string that is cryptographically secure, use GenerateRandom.

If you use the optional EncryptionContext field, you must store at least enough information to be able to reconstruct the full encryption context when you later send the ciphertext to the Decrypt operation. It is a good practice to choose an encryption context that you can reconstruct on the fly to better secure the ciphertext. For more information, see Encryption Context in the AWS Key Management Service Developer Guide.

Inheritance Hierarchy

System.Object
  Amazon.Runtime.AmazonWebServiceRequest
    Amazon.KeyManagementService.AmazonKeyManagementServiceRequest
      Amazon.KeyManagementService.Model.GenerateDataKeyRequest

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

Syntax

C#
public class GenerateDataKeyRequest : AmazonKeyManagementServiceRequest
         IAmazonWebServiceRequest

The GenerateDataKeyRequest type exposes the following members

Constructors

NameDescription
Public Method GenerateDataKeyRequest()

Properties

NameTypeDescription
Public Property EncryptionContext System.Collections.Generic.Dictionary<System.String, System.String>

Gets and sets the property EncryptionContext.

A set of key-value pairs that represents additional authenticated data.

For more information, see Encryption Context in the AWS Key Management Service Developer Guide.

Public Property GrantTokens System.Collections.Generic.List<System.String>

Gets and sets the property GrantTokens.

A list of grant tokens.

For more information, see Grant Tokens in the AWS Key Management Service Developer Guide.

Public Property KeyId System.String

Gets and sets the property KeyId.

The identifier of the CMK under which to generate and encrypt the data encryption key.

A valid identifier is the unique key ID or the Amazon Resource Name (ARN) of the CMK, or the alias name or ARN of an alias that refers to the CMK. Examples:

  • Unique key ID: 1234abcd-12ab-34cd-56ef-1234567890ab

  • CMK 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

Public Property KeySpec Amazon.KeyManagementService.DataKeySpec

Gets and sets the property KeySpec.

The length of the data encryption key. Use AES_128 to generate a 128-bit symmetric key, or AES_256 to generate a 256-bit symmetric key.

Public Property NumberOfBytes System.Int32

Gets and sets the property NumberOfBytes.

The length of the data encryption key in bytes. For example, use the value 64 to generate a 512-bit data key (64 bytes is 512 bits). For common key lengths (128-bit and 256-bit symmetric keys), we recommend that you use the KeySpec field instead of this one.

Examples

The following example generates a 256-bit symmetric data encryption key (data key) in two formats. One is the unencrypted (plainext) data key, and the other is the data key encrypted with the specified customer master key (CMK).

To generate a data key


var response = client.GenerateDataKey(new GenerateDataKeyRequest 
{
    KeyId = "alias/ExampleAlias", // The identifier of the CMK to use to encrypt the data key. You can use the key ID or Amazon Resource Name (ARN) of the CMK, or the name or ARN of an alias that refers to the CMK.
    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 CMK that was used to encrypt the data key.
MemoryStream plaintext = response.Plaintext; // The unencrypted (plaintext) data key.

            

Version Information

.NET Standard:
Supported in: 1.3

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

Portable Class Library:
Supported in: Windows Store Apps
Supported in: Windows Phone 8.1
Supported in: Xamarin Android
Supported in: Xamarin iOS (Unified)
Supported in: Xamarin.Forms