SM4 CBC模式加解密，有好的方案吗？

//加密代码 
async function SM4Encrypt(plainText: string, cipherKey: string): Promise<string> { 
  let sm4Generator = cryptoFramework.createSymKeyGenerator('SM4_128'); 
  let cipher = cryptoFramework.createCipher("SM4_128|CBC|PKCS7"); 
  let input: cryptoFramework.DataBlob = { data: stringToUint8Array(plainText) }; 
  try { 
    let ivdata: cryptoFramework.DataBlob = { data: stringToUint8Array('43pr5253zf5mm7jd') }; //偏移 
    let iv: cryptoFramework.IvParamsSpec = { iv: ivdata, algName: 'IvParamsSpec' } //cbc 模式的参数 
    let key: cryptoFramework.SymKey 
     
    /* 
     * 导入密钥的方式 
     * */ 
    let keydata: cryptoFramework.DataBlob = { data: stringToUint8Array(cipherKey) }; //密钥 
    key = await sm4Generator.convertKey(keydata); 
     
    /* 
     * 使用自创建生成的密钥 
     * */ 
    //key = await sm4Generator.generateSymKey(); 
    //加密 
    await cipher.init(cryptoFramework.CryptoMode.ENCRYPT_MODE, key, iv); 
    let cipherData = await cipher.doFinal(input) 
    message = base64.encodeToStringSync(cipherData.data) 
  } catch (err) { 
    console.log(err) 
  } 
  return message; 
} 
因为我的加解密是分开写的，所以为了保存加密之后的密文，我这里使用base64格式去保存了密文， 所以在解密的时候要用base64去转换为Uint8Arry. 
在正常使用过程中，解密要看传入的密文格式去对应的转换，如果出现解密结果乱码的情况，最下面附有对应的方法，可以尝试去使用。 
//解密代码如下： 
async function SM4Decrypt(ciphertext: string, cipherKey: string) { 
  let sm4Generator = cryptoFramework.createSymKeyGenerator("SM4_128") 
  let decoder = cryptoFramework.createCipher("SM4_128|CBC|PKCS7"); 
  //密文 
  let cipherData: cryptoFramework.DataBlob = { data: base64.decodeSync(ciphertext) }; 
  //密钥 
  let keydata: cryptoFramework.DataBlob = { data: stringToUint8Array(cipherKey) };  
  //偏移 
  let ivdata: cryptoFramework.DataBlob = { data: stringToUint8Array('43pr5253zf5mm7jd') }; 
  //cbc 模式的参数 
  let iv: cryptoFramework.IvParamsSpec = { iv: ivdata, algName: 'IvParamsSpec' }  
  let key: cryptoFramework.SymKey 
  try { 
    key = await sm4Generator.convertKey(keydata); 
    await decoder.init(cryptoFramework.CryptoMode.DECRYPT_MODE, key, iv); 
    let result = await decoder.doFinal(cipherData); 
    message = Utf8ArrayToStr(result.data); 
  } catch (err) { 
    console.log(err) 
  } 
}