AWS SDK Version 3 for .NET
API Reference

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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 an KMS 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 state: Effect on your KMS key 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:

Note:

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

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

Syntax

C#
public virtual ReEncryptResponse ReEncrypt(
         ReEncryptRequest request
)
Parameters
request
Type: Amazon.KeyManagementService.Model.ReEncryptRequest

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

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

Exceptions

ExceptionCondition
DependencyTimeoutException The system timed out while trying to fulfill the request. The request can be retried.
DisabledException The request was rejected because the specified KMS key is not enabled.
IncorrectKeyException The request was rejected because the specified KMS key cannot decrypt the data. The KeyId in a Decrypt request and the SourceKeyId in a ReEncrypt request must identify the same KMS key that was used to encrypt the ciphertext.
InvalidCiphertextException From the Decrypt or ReEncrypt operation, the request was rejected because the specified ciphertext, or additional authenticated data incorporated into the ciphertext, such as the encryption context, is corrupted, missing, or otherwise invalid. From the ImportKeyMaterial operation, the request was rejected because KMS could not decrypt the encrypted (wrapped) key material.
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, the KeyUsage must be SIGN_VERIFY. 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. For more information about how key state affects the use of a KMS key, see Key state: Effect on your KMS key in the Key Management Service Developer Guide.
NotFoundException The request was rejected because the specified entity or resource could not be found.

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 Framework:
Supported in: 4.5, 4.0, 3.5

See Also