harmony 鸿蒙Encryption and Decryption with an AES Symmetric Key (CBC Mode) (ArkTS)

2025-06-12
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Encryption and Decryption with an AES Symmetric Key (CBC Mode) (ArkTS)

For details about the algorithm specifications, see AES.

Encryption

Call cryptoFramework.createSymKeyGenerator and SymKeyGenerator.generateSymKey to generate a 128-bit AES symmetric key (SymKey).

In addition to the example in this topic, AES and Randomly Generating a Symmetric Key may help you better understand how to generate an AES symmetric key. Note that the input parameters in the reference documents may be different from those in the example below.

Call cryptoFramework.createCipher with the string parameter ‘AES128|CBC|PKCS7’ to create a Cipher instance for encryption. The key type is AES128, block cipher mode is CBC, and the padding mode is PKCS7.
Call Cipher.init to initialize the Cipher instance. In the Cipher.init API, set opMode to CryptoMode.ENCRYPT_MODE (encryption), key to SymKey (the key for encryption), and params to IvParamsSpec corresponding to the CBC mode.
If a small amount of data is to be encrypted, you can use Cipher.doFinal after Cipher.init to obtain the encrypted data.

Decryption

Call cryptoFramework.createCipher with the string parameter ‘AES128|CBC|PKCS7’ to create a Cipher instance for decryption. The key type is AES128, block cipher mode is CBC, and the padding mode is PKCS7.
Call Cipher.init to initialize the Cipher instance. In the Cipher.init API, set opMode to CryptoMode.DECRYPT_MODE (decryption), key to SymKey (the key for decryption), and params to IvParamsSpec corresponding to the CBC mode.
If a small amount of data is to be decrypted, you can use Cipher.doFinal after Cipher.init to obtain the decrypted data.
Example (using asynchronous APIs):

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

  function generateRandom(len: number) {
    let rand = cryptoFramework.createRandom();
    let generateRandSync = rand.generateRandomSync(len);
    return generateRandSync;
  }

  function genIvParamsSpec() {
    let ivBlob = generateRandom(16);
    let ivParamsSpec: cryptoFramework.IvParamsSpec = {
      algName: "IvParamsSpec",
      iv: ivBlob
    };
    return ivParamsSpec;
  }
  let iv = genIvParamsSpec();
  // Encrypt the message.
  async function encryptMessagePromise(symKey: cryptoFramework.SymKey, plainText: cryptoFramework.DataBlob) {
    let cipher = cryptoFramework.createCipher('AES128|CBC|PKCS7');
    await cipher.init(cryptoFramework.CryptoMode.ENCRYPT_MODE, symKey, iv);
    let cipherData = await cipher.doFinal(plainText);
    return cipherData;
  }
  // Decrypt the message.
  async function decryptMessagePromise(symKey: cryptoFramework.SymKey, cipherText: cryptoFramework.DataBlob) {
    let decoder = cryptoFramework.createCipher('AES128|CBC|PKCS7');
    await decoder.init(cryptoFramework.CryptoMode.DECRYPT_MODE, symKey, iv);
    let decryptData = await decoder.doFinal(cipherText);
    return decryptData;
  }

  async function genSymKeyByData(symKeyData: Uint8Array) {
    let symKeyBlob: cryptoFramework.DataBlob = { data: symKeyData };
    let aesGenerator = cryptoFramework.createSymKeyGenerator('AES128');
    let symKey = await aesGenerator.convertKey(symKeyBlob);
    console.info('convertKey success');
    return symKey;
  }

  async function aesCBC() {
    try {
      let keyData = new Uint8Array([83, 217, 231, 76, 28, 113, 23, 219, 250, 71, 209, 210, 205, 97, 32, 159]);
      let symKey = await genSymKeyByData(keyData);
      let message = "This is a test";
      let plainText: cryptoFramework.DataBlob = { data: new Uint8Array(buffer.from(message, 'utf-8').buffer) };
      let encryptText = await encryptMessagePromise(symKey, plainText);
      let decryptText = await decryptMessagePromise(symKey, encryptText);
      if (plainText.data.toString() === decryptText.data.toString()) {
        console.info('decrypt ok');
        console.info('decrypt plainText: ' + buffer.from(decryptText.data).toString('utf-8'));
      } else {
        console.error('decrypt failed');
      }
    } catch (error) {
      console.error(`AES CBC "${error}", error code: ${error.code}`);
    }
  }

Example (using synchronous APIs):

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

  function generateRandom(len: number) {
    let rand = cryptoFramework.createRandom();
    let generateRandSync = rand.generateRandomSync(len);
    return generateRandSync;
  }

  function genIvParamsSpec() {
    let ivBlob = generateRandom(16);
    let ivParamsSpec: cryptoFramework.IvParamsSpec = {
      algName: "IvParamsSpec",
      iv: ivBlob
    };
    return ivParamsSpec;
  }
  let iv = genIvParamsSpec();
  // Encrypt the message.
  function encryptMessage(symKey: cryptoFramework.SymKey, plainText: cryptoFramework.DataBlob) {
    let cipher = cryptoFramework.createCipher('AES128|CBC|PKCS7');
    cipher.initSync(cryptoFramework.CryptoMode.ENCRYPT_MODE, symKey, iv);
    let cipherData = cipher.doFinalSync(plainText);
    return cipherData;
  }
  // Decrypt the message.
  function decryptMessage(symKey: cryptoFramework.SymKey, cipherText: cryptoFramework.DataBlob) {
    let decoder = cryptoFramework.createCipher('AES128|CBC|PKCS7');
    decoder.initSync(cryptoFramework.CryptoMode.DECRYPT_MODE, symKey, iv);
    let decryptData = decoder.doFinalSync(cipherText);
    return decryptData;
  }

  function genSymKeyByData(symKeyData: Uint8Array) {
    let symKeyBlob: cryptoFramework.DataBlob = { data: symKeyData };
    let aesGenerator = cryptoFramework.createSymKeyGenerator('AES128');
    let symKey = aesGenerator.convertKeySync(symKeyBlob);
    console.info('convertKeySync success');
    return symKey;
  }

  function main() {
    try {
      let keyData = new Uint8Array([83, 217, 231, 76, 28, 113, 23, 219, 250, 71, 209, 210, 205, 97, 32, 159]);
      let symKey = genSymKeyByData(keyData);
      let message = "This is a test";
      let plainText: cryptoFramework.DataBlob = { data: new Uint8Array(buffer.from(message, 'utf-8').buffer) };
      let encryptText = encryptMessage(symKey, plainText);
      let decryptText = decryptMessage(symKey, encryptText);
      if (plainText.data.toString() === decryptText.data.toString()) {
        console.info('decrypt ok');
        console.info('decrypt plainText: ' + buffer.from(decryptText.data).toString('utf-8'));
      } else {
        console.error('decrypt failed');
      }
    } catch (error) {
      console.error(`AES CBC "${error}", error code: ${error.code}`);
    }
  }