调用cryptoFramework.createSymKeyGenerator、SymKeyGenerator.generateSymKey或SymKeyGenerator.convertKey，生成密钥算法为RC4、密钥长度在8位～4096位范围内（如RC4_128）的对称密钥（SymKey）。

如何生成RC4对称密钥，开发者可参考下文示例，并结合对称密钥生成和转换规格：RC4和指定二进制数据转换对称密钥理解，参考文档与当前示例可能存在入参差异，请在阅读时注意区分。
调用cryptoFramework.createCipher，指定字符串参数（如'RC4'），创建对称密钥类型为RC4的Cipher实例，用于完成加密操作。
调用Cipher.init，设置模式为加密（cryptoFramework.CryptoMode.ENCRYPT_MODE），指定加密密钥（SymKey），初始化加密Cipher实例。RC4为流密码，无IV等加解密参数时传入null。
当加密内容长度较短时，可以直接调用 Cipher.doFinal 而无需调用update，以获取加密后的数据。

解密

调用cryptoFramework.createCipher，指定字符串参数（如'RC4'），创建对称密钥类型为RC4的Cipher实例，用于完成解密操作。
调用Cipher.init，设置模式为解密（cryptoFramework.CryptoMode.DECRYPT_MODE），指定解密密钥（SymKey）初始化解密Cipher实例。无加解密参数时传入null。
当解密内容长度较短时，可以省略调用update，直接调用Cipher.doFinal，获取解密后的数据。

异步方法示例：

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


// 加密消息
async function encryptMessagePromise(symKey: cryptoFramework.SymKey, plainText: cryptoFramework.DataBlob) {
  let cipher = cryptoFramework.createCipher('RC4');
  await cipher.init(cryptoFramework.CryptoMode.ENCRYPT_MODE, symKey, null);
  let cipherData = await cipher.doFinal(plainText);
  return cipherData;
}

// 解密消息
async function decryptMessagePromise(symKey: cryptoFramework.SymKey, cipherText: cryptoFramework.DataBlob) {
  let decoder = cryptoFramework.createCipher('RC4');
  await decoder.init(cryptoFramework.CryptoMode.DECRYPT_MODE, symKey, null);
  let decryptData = await decoder.doFinal(cipherText);
  return decryptData;
}

async function genSymKeyByData(symKeyData: Uint8Array) {
  let symKeyBlob: cryptoFramework.DataBlob = { data: symKeyData };
  let rc4Generator = cryptoFramework.createSymKeyGenerator('RC4');
  let symKey = await rc4Generator.convertKey(symKeyBlob);
  console.info('convertKey result: success.');
  return symKey;
}

async function rc4EncryptionDecryption() {
  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.');
  }
}

同步方法示例：

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


// 加密消息
function encryptMessage(symKey: cryptoFramework.SymKey, plainText: cryptoFramework.DataBlob) {
  let cipher = cryptoFramework.createCipher('RC4');
  cipher.initSync(cryptoFramework.CryptoMode.ENCRYPT_MODE, symKey, null);
  let cipherData = cipher.doFinalSync(plainText);
  return cipherData;
}

// 解密消息
function decryptMessage(symKey: cryptoFramework.SymKey, cipherText: cryptoFramework.DataBlob) {
  let decoder = cryptoFramework.createCipher('RC4');
  decoder.initSync(cryptoFramework.CryptoMode.DECRYPT_MODE, symKey, null);
  let decryptData = decoder.doFinalSync(cipherText);
  return decryptData;
}

function genSymKeyByData(symKeyData: Uint8Array) {
  let symKeyBlob: cryptoFramework.DataBlob = { data: symKeyData };
  let rc4Generator = cryptoFramework.createSymKeyGenerator('RC4');
  let symKey = rc4Generator.convertKeySync(symKeyBlob);
  console.info('convertKeySync result: success.');
  return symKey;
}

function rc4EncryptionDecryption() {
  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.');
  }
}

目录

使用RC4对称密钥加解密(ArkTS)