Help Center/ Data Encryption Workshop/ API Reference (Paris and Amsterdam Regions)/ APIs/ Encrypting a DEK
Updated on 2022-12-06 GMT+08:00
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Encrypting a DEK

Function

This API enables you to encrypt a DEK using a specified CMK.

URI

  • URI format

    POST /v1.0/{project_id}/kms/encrypt-datakey

  • Parameter description
    Table 1 Parameter description

    Parameter

    Mandatory

    Type

    Description

    project_id

    Yes

    String

    Project ID

Requests

Table 2 Request parameters

Parameter

Mandatory

Type

Description

key_id

Yes

String

36-byte ID of a CMK that matches the regular expression ^[0-9a-z]{8}-[0-9a-z]{4}-[0-9a-z]{4}-[0-9a-z]{4}-[0-9a-z]{12}$

Example: 0d0466b0-e727-4d9c-b35d-f84bb474a37f

encryption_context

No

Object

Key-value pairs with a maximum length of 8192 characters. This parameter is used to record resource context information, excluding sensitive information, to ensure data integrity.

If this parameter is specified during encryption, it is also required for decryption.

Example: {"Key1":"Value1","Key2":"Value2"}

plain_text

Yes

String

Hexadecimal character string concatenated from plaintext of a DEK and the plaintext digest (32-byte character string generated using SHA256)

For details, see Examples.

datakey_plain_length

Yes

String

Number of bytes of a DEK in plaintext. The value is 64.

sequence

No

String

36-byte serial number of a request message

Example: 919c82d4-8046-4722-9094-35c3c6524cff

Responses

Table 3 Response parameters

Parameter

Mandatory

Type

Description

key_id

Yes

String

CMK ID

cipher_text

Yes

String

The ciphertext of a DEK is expressed in hexadecimal format, and two characters indicate one byte.

datakey_length

Yes

String

Number of bytes in the length of a DEK

Examples

In the following example, the 512-bit plaintext DEK (7549d9aea901767bf3c0b3e14b10722eaf6f59053bbd82045d04e075e809a0fe6ccab48f8e5efe74e4b18ff0512525e527b10331100f357bf42125d8d5ced94f) generated from the customer master key whose key ID is 0d0466b0-e727-4d9c-b35d-f84bb474a37f can be obtained through the API in Creating a DEK.

The digest of the plaintext DEK is fbc8ac72b0785ca7fe33eb6776ce3990b11e32b299d9c0a9ee0305fb9540f797. The method for calculating the digest is as follows:

//Digest calculation
public static byte[] sha256(byte[] cmkData) { 
    byte[] digest = new byte[0];  
   try {  
       MessageDigest md = MessageDigest.getInstance("SHA-256");
         md.update(cmkData); 
        digest = md.digest();
     } catch (Exception e) { 
        System.out.println("calculate digest failure, exception is " + e.toString()); 
    } 
     return digest; 
}
//Convert the obtained digest into a hexadecimal character string.
public static String bytesToHexString(byte[] digest) {
        ...
}

The value of plain_text (a hexadecimal character string concatenated from plaintext of the DEK and the plaintext digest) is 7549d9aea901767bf3c0b3e14b10722eaf6f59053bbd82045d04e075e809a0fe6ccab48f8e5efe74e4b18ff0512525e527b10331100f357bf42125d8d5ced94f fbc8ac72b0785ca7fe33eb6776ce3990b11e32b299d9c0a9ee0305fb9540f797.

  • Example request 
    {
    "key_id": "0d0466b0-e727-4d9c-b35d-f84bb474a37f",
    "plain_text": "7549d9aea901767bf3c0b3e14b10722eaf6f59053bbd82045d04e075e809a0fe6ccab48f8e5efe74e4b18ff0512525e527b10331100f357bf42125d8d5ced94f fbc8ac72b0785ca7fe33eb6776ce3990b11e32b299d9c0a9ee0305fb9540f797",
    "datakey_plain_length": "64"
}
  • Example response 
    {
    "key_id": "0d0466b0-e727-4d9c-b35d-f84bb474a37f",
    "cipher_text": "020098005273E14E6E8E95F5463BECDC27E80AF820B9FC086CB47861899149F67CF07DAFF2810B7D27BDF19AB7632488E0926A48DB2FC85BEA905119411B46244C5E6B8036C60A0B0B4842FFE6994518E89C19B1C1D688D9043BCD6053EA7BA0652642CE59F2543C80669139F4F71ABB9BD9A24330643034363662302D653732372D346439632D623335642D66383462623437346133376600000000D34457984F9730D57F228C210FD22CA6017913964B21D4ECE45D81092BB9112E",
    "datakey_length": "64"
}

    or

    {
    "error": {
        "error_code": "KMS.XXXX",
        "error_msg": "XXX"
    }
}

Status Codes

Table 4 lists the normal status code returned by the response.
Table 4 Status codes

Status Code

Status

Description

200

OK

Request processed successfully.

Exception status code. For details, see Status Codes.

Parent topic: APIs