Generates a random data key that is used to encrypt on-premises data.
Usage notes
- Keys outside Key Management Service (KMS) instances: To perform cryptographic operations, use Alibaba Cloud SDK to call operations.
- Keys in KMS instances: To perform cryptographic operations, use one of the following methods:
- Method 1 (recommended): Use KMS Instance SDK to call KMS Instance API operations. For more information, see KMS Instance SDK and KMS Instance API.
- Method 2: Use Alibaba Cloud SDK to call operations. The authentication method supports only RAM roles whose trusted entities are Alibaba Cloud services. For more information, see Create a RAM role for a trusted Alibaba Cloud service.
QPS limits
You can call this operation up to 750 times per second per account. If the number of the calls per second exceeds the limit, throttling is triggered. As a result, your business may be affected. We recommend that you take note of the limit when you call this operation.
Description
This operation creates a random data key, encrypts the data key by using a key, and returns the plaintext and ciphertext of the data key. You can use the data key plaintext to encrypt on-premises data without using KMS. You must store the data ciphertext together with the data key ciphertext. You can obtain the data key plaintext from Plaintext in the response and the data key ciphertext from CiphertextBlob in the response.
The key that you specify in the request is only used to encrypt the data key and is not involved in the generation of the data key. KMS does not record or store the data key. Therefore, you must store the data key ciphertext in persistent storage.
We recommend that you encrypt on-premises data by performing the following steps:
1. Call the GenerateDataKey operation to obtain a data key that is used for data encryption.
2. Use the data key plaintext that you obtain to encrypt on-premises data without using KMS. Then, delete the data key plaintext from the memory.
3. Store the data ciphertext together with the data key ciphertext that you obtain.
We recommend that you decrypt on-premises data by performing the following steps:
- Call the Decrypt operation to decrypt the locally stored data key ciphertext. The data key plaintext is returned.
- Use the data key plaintext to decrypt on-premises data and then delete the data key plaintext from the memory.
In this example, a random data key is generated for a key whose ID is 7906979c-8e06-46a2-be2d-68e3ccbc****
.
Debugging
Request parameters
Parameter |
Type |
Required |
Example |
Description |
Action | String | Yes | GenerateDataKey | The operation that you want to perform. Set the value to GenerateDataKey. |
KeyId | String | Yes | 7906979c-8e06-46a2-be2d-68e3ccbc**** | The ID of the key. The ID must be globally unique. You can also set this parameter to an alias that is bound to the key. For more information, see Alias overview. |
KeySpec | String | No | AES_256 | The type of the data key. Valid values:
Note We recommend that you use KeySpec or NumberOfBytes to specify the length of a data key. If none of the parameters are specified, KMS generates a 256-bit data key. If both parameters are specified, KMS ignores KeySpec. |
NumberOfBytes | Integer | No | 256 | The length of the data key. Unit: bytes. Valid values: 1 to 1024. Default values:
|
EncryptionContext | Map | No | {"Example":"Example"} | The JSON string that consists of key-value pairs. If you configure this parameter, an equivalent value is required when you call the Decrypt operation. For more information, see EncryptionContext. |
For more information about common request parameters, see Common parameters.
Response parameters
Parameter |
Type |
Example |
Description |
KeyVersionId | String | 2ab1a983-7072-4bbc-a582-584b5bd8**** | The version ID of the key. The ID must be globally unique. |
KeyId | String | 7906979c-8e06-46a2-be2d-68e3ccbc**** | The ID of the key. The ID must be globally unique. Note If KeyId is set to an alias of the key, the ID of the key to which the alias is bound is returned. |
CiphertextBlob | String | ODZhOWVmZDktM2QxNi00ODk0LWJkNGYtMWZjNDNmM2YyYWJmS7FmDBBQ0BkKsQrtRnidtPwirmDcS0ZuJCU41xxAAWk4Z8qsADfbV0b+i6kQmlvj79dJdGOvtX69Uycs901qOjop4bTS**** | The data key ciphertext that is encrypted by using the primary version of the key. |
RequestId | String | 7021b6ec-4be7-4d3c-8a68-1e85d4d515a0 | The ID of the request, which is used to locate and troubleshoot issues. |
Plaintext | String | QmFzZTY0IGVuY29kZWQgcGxhaW50**** | The Base64 encoded data key plaintext. |
Examples
Sample requests
http(s)://[Endpoint]/?Action=GenerateDataKey
&KeyId=7906979c-8e06-46a2-be2d-68e3ccbc****
&KeySpec=AES_256
&NumberOfBytes=256
&Common request parameters
Sample success responses
XML
format
HTTP/1.1 200 OK
Content-Type:application/xml
<GenerateDataKeyResponse>
<KeyVersionId>2ab1a983-7072-4bbc-a582-584b5bd8****</KeyVersionId>
<KeyId>7906979c-8e06-46a2-be2d-68e3ccbc****</KeyId>
<CiphertextBlob>ODZhOWVmZDktM2QxNi00ODk0LWJkNGYtMWZjNDNmM2YyYWJmS7FmDBBQ0BkKsQrtRnidtPwirmDcS0ZuJCU41xxAAWk4Z8qsADfbV0b+i6kQmlvj79dJdGOvtX69Uycs901qOjop4bTS****</CiphertextBlob>
<RequestId>7021b6ec-4be7-4d3c-8a68-1e85d4d515a0</RequestId>
<Plaintext>QmFzZTY0IGVuY29kZWQgcGxhaW50****</Plaintext>
</GenerateDataKeyResponse>
JSON
format
HTTP/1.1 200 OK
Content-Type:application/json
{
"KeyVersionId" : "2ab1a983-7072-4bbc-a582-584b5bd8****",
"KeyId" : "7906979c-8e06-46a2-be2d-68e3ccbc****",
"CiphertextBlob" : "ODZhOWVmZDktM2QxNi00ODk0LWJkNGYtMWZjNDNmM2YyYWJmS7FmDBBQ0BkKsQrtRnidtPwirmDcS0ZuJCU41xxAAWk4Z8qsADfbV0b+i6kQmlvj79dJdGOvtX69Uycs901qOjop4bTS****",
"RequestId" : "7021b6ec-4be7-4d3c-8a68-1e85d4d515a0",
"Plaintext" : "QmFzZTY0IGVuY29kZWQgcGxhaW50****"
}
Error codes
HTTP status code |
Error code |
Error message |
Description |
400 | UnsupportedOperation | This action is not supported. | The operation is not supported. |
404 | Forbidden.AliasNotFound | The specified Alias is not found. | The specified alias is not found. |
404 | Forbidden.KeyNotFound | The specified Key is not found. | The specified key does not exist. |
409 | Rejected.Disabled | The request was rejected because the key state is Disabled. | The request is denied because the key is disabled. |
409 | Rejected.PendingDeletion | The request was rejected because the key state is PendingDeletion. | The request is denied because the key is in the Pending Deletion state. |
409 | Rejected.Unavailable | The request was rejected because the key state is Unavailable. | The request is denied because the key is unavailable. |
For a list of error codes, see Service error codes.