AWS SDK Version 3 for .NET
API Reference

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Container for the parameters to the ReEncrypt operation. Decrypts ciphertext and then reencrypts it entirely within KMS. You can use this operation to change the KMS key under which data is encrypted, such as when you manually rotate a KMS key or change the KMS key that protects a ciphertext. You can also use it to reencrypt ciphertext under the same KMS key, such as to change the encryption context of a ciphertext.

The ReEncrypt operation can decrypt ciphertext that was encrypted by using a KMS key in an KMS operation, such as Encrypt or GenerateDataKey. It can also decrypt ciphertext that was encrypted by using the public key of an asymmetric KMS key outside of KMS. However, it cannot decrypt ciphertext produced by other libraries, such as the Amazon Web Services Encryption SDK or Amazon S3 client-side encryption. These libraries return a ciphertext format that is incompatible with KMS.

When you use the ReEncrypt operation, you need to provide information for the decrypt operation and the subsequent encrypt operation.

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. The source KMS key and destination KMS key can be in different Amazon Web Services accounts. Either or both KMS keys can be in a different account than the caller. To specify a KMS key in a different account, you must use its key ARN or alias ARN.

Required permissions:

To permit reencryption from or to a KMS key, include the "kms:ReEncrypt*" permission in your key policy. This permission is automatically included in the key policy when you use the console to create a KMS key. But you must include it manually when you create a KMS key programmatically or when you use the PutKeyPolicy operation to set a key policy.

Related operations:

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

Inheritance Hierarchy

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

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

Syntax

C#
public class ReEncryptRequest : AmazonKeyManagementServiceRequest
         IAmazonWebServiceRequest

The ReEncryptRequest type exposes the following members

Constructors

NameDescription
Public Method ReEncryptRequest()

Properties

NameTypeDescription
Public Property CiphertextBlob System.IO.MemoryStream

Gets and sets the property CiphertextBlob.

Ciphertext of the data to reencrypt.

Public Property DestinationEncryptionAlgorithm Amazon.KeyManagementService.EncryptionAlgorithmSpec

Gets and sets the property DestinationEncryptionAlgorithm.

Specifies the encryption algorithm that KMS will use to reecrypt the data after it has decrypted it. The default value, SYMMETRIC_DEFAULT, represents the encryption algorithm used for symmetric encryption KMS keys.

This parameter is required only when the destination KMS key is an asymmetric KMS key.

Public Property DestinationEncryptionContext System.Collections.Generic.Dictionary<System.String, System.String>

Gets and sets the property DestinationEncryptionContext.

Specifies that encryption context to use when the reencrypting the data.

Do not include confidential or sensitive information in this field. This field may be displayed in plaintext in CloudTrail logs and other output.

A destination encryption context is valid only when the destination KMS key is a symmetric encryption KMS key. The standard ciphertext format for asymmetric KMS keys does not include fields for metadata.

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 Key Management Service Developer Guide.

Public Property DestinationKeyId System.String

Gets and sets the property DestinationKeyId.

A unique identifier for the KMS key that is used to reencrypt the data. Specify a symmetric encryption KMS key or an asymmetric KMS key with a KeyUsage value of ENCRYPT_DECRYPT. To find the KeyUsage value of a 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 Amazon Web Services 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.

Public Property DryRun System.Boolean

Gets and sets the property DryRun.

Checks if your request will succeed. DryRun is an optional parameter.

To learn more about how to use this parameter, see Testing your KMS API calls in the 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.

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 Key Management Service Developer Guide.

Public Property SourceEncryptionAlgorithm Amazon.KeyManagementService.EncryptionAlgorithmSpec

Gets and sets the property SourceEncryptionAlgorithm.

Specifies the encryption algorithm that KMS will use to decrypt the ciphertext before it is reencrypted. The default value, SYMMETRIC_DEFAULT, represents the algorithm used for symmetric encryption KMS keys.

Specify the same algorithm that was used to encrypt the ciphertext. If you specify a different algorithm, the decrypt attempt fails.

This parameter is required only when the ciphertext was encrypted under an asymmetric KMS key.

Public Property SourceEncryptionContext System.Collections.Generic.Dictionary<System.String, System.String>

Gets and sets the property SourceEncryptionContext.

Specifies the encryption context to use to decrypt the ciphertext. Enter the same encryption context that was used to encrypt the ciphertext.

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 Key Management Service Developer Guide.

Public Property SourceKeyId System.String

Gets and sets the property SourceKeyId.

Specifies the KMS key that KMS will use to decrypt the ciphertext before it is re-encrypted.

Enter a key ID of the KMS key that was used to encrypt the ciphertext. If you identify a different KMS key, the ReEncrypt operation throws an IncorrectKeyException.

This parameter is required only when the ciphertext was encrypted under an asymmetric KMS key. If you used a symmetric encryption KMS key, KMS can get the KMS key from metadata that it adds to the symmetric ciphertext blob. However, it is always recommended as a best practice. This practice ensures that you use the KMS key that you intend.

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 Amazon Web Services 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.

Examples

The following example reencrypts data with the specified KMS key.

To reencrypt data


var client = new AmazonKeyManagementServiceClient();
var response = client.ReEncrypt(new ReEncryptRequest 
{
    CiphertextBlob = new MemoryStream(<binary data>), // The data to reencrypt.
    DestinationKeyId = "0987dcba-09fe-87dc-65ba-ab0987654321" // The identifier of the KMS key to use to reencrypt the data. You can use any valid key identifier.
});

MemoryStream ciphertextBlob = response.CiphertextBlob; // The reencrypted data.
string keyId = response.KeyId; // The ARN of the KMS key that was used to reencrypt the data.
string sourceKeyId = response.SourceKeyId; // The ARN of the KMS key that was originally used to encrypt the data.

            

Version Information

.NET Core App:
Supported in: 3.1

.NET Standard:
Supported in: 2.0

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