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AWS Key Management Service
API Reference (API Version 2014-11-01)

AWS Documentation » AWS KMS » API Reference » Actions » ReEncrypt

ReEncrypt

Encrypts data on the server side with a new customer master key (CMK) without exposing the plaintext of the data on the client side. The data is first decrypted and then reencrypted. You can also use this operation to change the encryption context of a ciphertext.

You can reencrypt data using CMKs in different AWS accounts.

Unlike other operations, ReEncrypt is authorized twice, once as ReEncryptFrom on the source CMK and once as ReEncryptTo on the destination CMK. We recommend that you include the "kms:ReEncrypt*" permission in your key policies to permit reencryption from or to the CMK. This permission is automatically included in the key policy when you create a CMK through the console, but you must include it manually when you create a CMK programmatically or when you set a key policy with the PutKeyPolicy operation.

The result of this operation varies with the key state of the CMK. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Request Syntax

{
   "CiphertextBlob": blob,
   "DestinationEncryptionContext": { 
      "string" : "string" 
   },
   "DestinationKeyId": "string",
   "GrantTokens": [ "string" ],
   "SourceEncryptionContext": { 
      "string" : "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.

Note

In the following list, the required parameters are described first.

CiphertextBlob

Ciphertext of the data to reencrypt.

Type: Base64-encoded binary data object

Length Constraints: Minimum length of 1. Maximum length of 6144.

Required: Yes

DestinationKeyId

A unique identifier for the CMK that is used to reencrypt the data.

To specify a CMK, use its key ID, Amazon Resource Name (ARN), alias name, or alias ARN. When using an alias name, prefix it with "alias/". To specify a CMK 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 CMK, 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

DestinationEncryptionContext

Encryption context to use when the data is reencrypted.

Type: String to string map

Required: No

GrantTokens

A list of grant tokens.

For more information, see Grant Tokens 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

SourceEncryptionContext

Encryption context used to encrypt and decrypt the data specified in the CiphertextBlob parameter.

Type: String to string map

Required: No

Response Syntax

{
   "CiphertextBlob": blob,
   "KeyId": "string",
   "SourceKeyId": "string"
}

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.

CiphertextBlob

The reencrypted data. When you use the HTTP API or the AWS CLI, the value is Base64-encdoded. Otherwise, it is not encoded.

Type: Base64-encoded binary data object

Length Constraints: Minimum length of 1. Maximum length of 6144.

KeyId

Unique identifier of the CMK used to reencrypt the data.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 2048.

SourceKeyId

Unique identifier of the CMK used to originally encrypt the data.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 2048.

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. The request can be retried.

HTTP Status Code: 500

DisabledException

The request was rejected because the specified CMK is not enabled.

HTTP Status Code: 400

InvalidCiphertextException

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.

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 because the specified KeySpec value is not valid.

HTTP Status Code: 400

KeyUnavailableException

The request was rejected because the specified CMK was not available. The request can be retried.

HTTP Status Code: 500

KMSInternalException

The request was rejected because an internal exception occurred. The request can be retried.

HTTP Status Code: 400

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 CMK, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

HTTP Status Code: 400

NotFoundException

The request was rejected because the specified entity or resource could not be found.

HTTP Status Code: 400

Examples

The following examples are formatted for legibility.

Example Request

POST / HTTP/1.1
Host: kms.us-east-2.amazonaws.com
Content-Length: 306
X-Amz-Target: TrentService.ReEncrypt
X-Amz-Date: 20161207T225816Z
Content-Type: application/x-amz-json-1.1
Authorization: AWS4-HMAC-SHA256\
 Credential=AKIAI44QH8DHBEXAMPLE/20161207/us-east-2/kms/aws4_request,\
 SignedHeaders=content-type;host;x-amz-date;x-amz-target,\
 Signature=7afd339e2a680e0726592ddf687aabe48e1d8a7933a60ebbdc0154b8e2936ef2

{
  "DestinationKeyId": "0987dcba-09fe-87dc-65ba-ab0987654321",
  "CiphertextBlob": "AQECAHj/M9MyvNsMT8kW+K5DVkMfunTHr0w6V6crnuAGw80uRwAAAH0wewYJKoZIhvcNAQcGoG4wbAIBADBnBgkqhkiG9w0BBwEwHgYJYIZIAWUDBAEuMBEEDPXExREUtnnGy1wC3wIBEIA6LvpU7BRMW+FSkUmNmmE0H0aHHRYRD6XqUnaCNnzAuhhq4VTGBfii6oWtjVU83pGmradvUawxE/tbCg=="
}

Example Response

HTTP/1.1 200 OK
Server: Server
Date: Wed, 07 Dec 2016 22:58:17 GMT
Content-Type: application/x-amz-json-1.1
Content-Length: 423
Connection: keep-alive
x-amzn-RequestId: a434eca2-bcd0-11e6-b60b-ffb5eb2d1d15

{
  "CiphertextBlob": "AQECAHjRYf5WytIc0C857tFSnBaPn2F8DgfmThbJlGfR8P3WlwAAAH0wewYJKoZIhvcNAQcGoG4wbAIBADBnBgkqhkiG9w0BBwEwHgYJYIZIAWUDBAEuMBEEDIwicafp/vwjXjPBhQIBEIA6wjfzufQPhuU+nVqa3Kj4nqSTdhDw1PTkImKCUEuvQDui6qsooyB4Qxe8OOBqciRNC7ENQN8lKaEijg==",
  "KeyId": "arn:aws:kms:us-east-2:111122223333:key/0987dcba-09fe-87dc-65ba-ab0987654321",
  "SourceKeyId": "arn:aws:kms:us-east-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab"
}

See Also

For more information about using this API in one of the language-specific AWS SDKs, see the following: