Key Derivation Using X963KDF (ArkTS)

From API version 22, the crypto algorithm library supports key derivation with X963KDF.

For details about the corresponding algorithm specifications, see X963KDF.

How to Develop

Create an X963KdfSpec object and use it as a parameter for key derivation.

X963KdfSpec is a child class of KdfSpec. You need to specify the following:
- algName: algorithm to use, which is 'X963Kdf'.
- key: original key material.
  
  If the string type is used, pass in the data used for key derivation instead of the string type such as HexString or base64. In addition, ensure that the string is encoded in UTF-8 format. Otherwise, the derived key may be different from what you expected.
- info: optional context and application information used to extend the short key. This parameter can be empty.
- keySize: length of the key to derive, in bytes. The value must be a positive integer.
Call cryptoFramework.createKdf with the string parameter 'X963KDF|SHA256' to create a Kdf object. The key derivation algorithm is X963KDF, and HMAC algorithm is SHA256.
Call Kdf.generateSecret with the X963KdfSpec object to generate a derived key.

The following table lists how Kdf.generateSecret delivers the return value.

Name	Return Mode
generateSecret(params: KdfSpec, callback: AsyncCallback<DataBlob>): void	This API uses an asynchronous callback to return the result.
generateSecret(params: KdfSpec): Promise<DataBlob>	This API uses a promise to return the result.
generateSecretSync(params: KdfSpec): DataBlob	This API returns the result synchronously.

Return the result using await:


import { cryptoFramework } from '@kit.CryptoArchitectureKit';
import { buffer } from '@kit.ArkTS';

async function kdfAwait() {
  let keyData = new Uint8Array(buffer.from('012345678901234567890123456789', 'utf-8').buffer);
  let infoData = new Uint8Array(buffer.from('infostring', 'utf-8').buffer);
  let spec: cryptoFramework.X963KdfSpec = {
    algName: 'X963KDF',
    key: keyData,
    info: infoData,
    keySize: 32
  };
  let kdf = cryptoFramework.createKdf('X963KDF|SHA256');
  let secret = await kdf.generateSecret(spec);
  console.info('key derivation output: ' + secret.data);
}

Return the result using a promise:


import { cryptoFramework } from '@kit.CryptoArchitectureKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { buffer } from '@kit.ArkTS';

function kdfPromise() {
  let keyData = new Uint8Array(buffer.from('012345678901234567890123456789', 'utf-8').buffer);
  let infoData = new Uint8Array(buffer.from('infostring', 'utf-8').buffer);
  let spec: cryptoFramework.X963KdfSpec = {
    algName: 'X963KDF',
    key: keyData,
    info: infoData,
    keySize: 32
  };
  let kdf = cryptoFramework.createKdf('X963KDF|SHA256');
  let kdfPromise = kdf.generateSecret(spec);
  kdfPromise.then((secret) => {
    console.info('key derivation output: ' + secret.data);
  }).catch((error: BusinessError) => {
    console.error(`key derivation failed: errCode: ${error.code}, message: ${error.message}`);
  });
}

Return the result synchronously:

import { cryptoFramework } from '@kit.CryptoArchitectureKit';
import { buffer } from '@kit.ArkTS';

function kdfSync() {
  let keyData = new Uint8Array(buffer.from('012345678901234567890123456789', 'utf-8').buffer);
  let infoData = new Uint8Array(buffer.from('infostring', 'utf-8').buffer);
  let spec: cryptoFramework.X963KdfSpec = {
    algName: 'X963KDF',
    key: keyData,
    info: infoData,
    keySize: 32
  };
  let kdf = cryptoFramework.createKdf('X963KDF|SHA256');
  let secret = kdf.generateSecretSync(spec);
  console.info('[Sync]key derivation output: ' + secret.data);
}