HarmonyOS 鸿蒙Next 如何给加解密方法拓展加解密文件功能？

HarmonyOS 鸿蒙Next 如何给加解密方法拓展加解密文件功能？

// SM4 加密
async SM4Encrypt(plainText: string, key: string): Promise<string> {
let cipherKey = this.ivMap[key][0]
let cipherIv = this.ivMap[key][1]

let sm4Generator = cryptoFramework.createSymKeyGenerator('SM4_128');
let cipher = cryptoFramework.createCipher(cipherIv ? "SM4_128|CBC|PKCS7" : "SM4_128|ECB|PKCS7");
let input: cryptoFramework.DataBlob = {
data: new Uint8Array(buffer.from(plainText, 'utf-8').buffer)
};
try {
let iv: cryptoFramework.IvParamsSpec | null = null
if (cipherIv) {
iv = {
iv: {
data: new Uint8Array(buffer.from(cipherIv, 'hex').buffer)
},
algName: 'IvParamsSpec'
}
}
let symKey = await sm4Generator.convertKey({
data: new Uint8Array(buffer.from(cipherKey, 'hex').buffer)
});
await cipher.init(cryptoFramework.CryptoMode.ENCRYPT_MODE, symKey, iv);
let cipherData = await cipher.doFinal(input)
return new util.Base64Helper().encodeToStringSync(cipherData.data)
} catch (err) {
console.log(err)
}

return "";
}

// SM4 解密
async SM4Decrypt(ciphertext: string, key: string) {
let cipherKey = this.ivMap[key][0]
let cipherIv = this.ivMap[key][1]

const base64 = new util.Base64Helper()
let sm4Generator = cryptoFramework.createSymKeyGenerator("SM4_128")
let decoder = cryptoFramework.createCipher(cipherIv ? "SM4_128|CBC|PKCS7" : "SM4_128|ECB|PKCS7");
//密文
let cipherData: cryptoFramework.DataBlob = {
data: base64.decodeSync(ciphertext)
};
//密钥
let keydata: cryptoFramework.DataBlob = {
data: new Uint8Array(buffer.from(cipherKey, 'hex').buffer)
};
let iv: cryptoFramework.IvParamsSpec | null = null
if (cipherIv) {
iv = {
iv: {
data: new Uint8Array(buffer.from(cipherIv, 'hex').buffer)
}, algName: 'IvParamsSpec'
}
}
let symKey = await sm4Generator.convertKey(keydata);
await decoder.init(cryptoFramework.CryptoMode.DECRYPT_MODE, symKey, iv);
let result = await decoder.doFinal(cipherData);
return buffer.from(result.data).toString('utf8')
}