针对C＃和javascript的兼容AES加密和解密

Question

我正在尝试用C＃和Javascript编写两个类，我可以在整个项目中使用它来在交换数据时使用AES加密或解密数据。

使用AES我在加密结果中嵌入Salt（32字节）和IV（16字节），这在测试时单独适用于两个类。将Salt和IV添加到混合中并没有引出很多参考，以使这两个平台之间的工作。

对于C＃，我使用标准的System.Security.Cryptography.AES

 private static readonly int iterations = 1000;

    public static string Encrypt(string input, string password)
    {
        byte[] encrypted;
        byte[] IV;
        byte[] Salt = GetSalt();
        byte[] Key = CreateKey(password, Salt);

        using (Aes aesAlg = Aes.Create())
        {
            aesAlg.Key = Key;
            aesAlg.Padding = PaddingMode.PKCS7;
            aesAlg.Mode = CipherMode.CBC;

            aesAlg.GenerateIV();
            IV = aesAlg.IV;

            var encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);

            using (var msEncrypt = new MemoryStream())
            {
                using (var csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                {
                    using (var swEncrypt = new StreamWriter(csEncrypt))
                    {
                        swEncrypt.Write(input);
                    }
                    encrypted = msEncrypt.ToArray();
                }
            }
        }

        byte[] combinedIvSaltCt = new byte[Salt.Length + IV.Length + encrypted.Length];
        Array.Copy(Salt, 0, combinedIvSaltCt, 0, Salt.Length);
        Array.Copy(IV, 0, combinedIvSaltCt, Salt.Length, IV.Length);
        Array.Copy(encrypted, 0, combinedIvSaltCt, Salt.Length + IV.Length, encrypted.Length);

        return Convert.ToBase64String(combinedIvSaltCt.ToArray());
    }

    public static string Decrypt(string input, string password)
    {
        byte[] inputAsByteArray;
        string plaintext = null;
        try
        {
            inputAsByteArray = Convert.FromBase64String(input);

            byte[] Salt = new byte[32];
            byte[] IV = new byte[16];
            byte[] Encoded = new byte[inputAsByteArray.Length - Salt.Length - IV.Length];

            Array.Copy(inputAsByteArray, 0, Salt, 0, Salt.Length);
            Array.Copy(inputAsByteArray, Salt.Length, IV, 0, IV.Length);
            Array.Copy(inputAsByteArray, Salt.Length + IV.Length, Encoded, 0, Encoded.Length);

            byte[] Key = CreateKey(password, Salt);

            using (Aes aesAlg = Aes.Create())
            {
                aesAlg.Key = Key;
                aesAlg.IV = IV;
                aesAlg.Mode = CipherMode.CBC;
                aesAlg.Padding = PaddingMode.PKCS7;

                ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);

                using (var msDecrypt = new MemoryStream(Encoded))
                {
                    using (var csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                    {
                        using (var srDecrypt = new StreamReader(csDecrypt))
                        {
                            plaintext = srDecrypt.ReadToEnd();
                        }
                    }
                }
            }

            return plaintext;
        }
        catch (Exception e)
        {
            return null;
        }
    }

    public static byte[] CreateKey(string password, byte[] salt)
    {
        using (var rfc2898DeriveBytes = new Rfc2898DeriveBytes(password, salt, iterations))
            return rfc2898DeriveBytes.GetBytes(32);
    }

    private static byte[] GetSalt()
    {
        var salt = new byte[32];
        using (var random = new RNGCryptoServiceProvider())
        {
            random.GetNonZeroBytes(salt);
        }

        return salt;
    }

对于Javascript解决方案，我使用CryptoJS，基于此参考http://www.adonespitogo.com/articles/encrypting-data-with-cryptojs-aes/

    var keySize = 256;
var ivSize = 128;
var saltSize = 256;
var iterations = 1000;

var message = "Hello World";
var password = "Secret Password";


function encrypt (msg, pass) {
  var salt = CryptoJS.lib.WordArray.random(saltSize/8);

  var key = CryptoJS.PBKDF2(pass, salt, {
      keySize: keySize/32,
      iterations: iterations
    });

  var iv = CryptoJS.lib.WordArray.random(ivSize/8);

  var encrypted = CryptoJS.AES.encrypt(msg, key, { 
    iv: iv, 
    padding: CryptoJS.pad.Pkcs7,
    mode: CryptoJS.mode.CBC

  });

  // salt, iv will be hex 32 in length
  // append them to the ciphertext for use  in decryption
  var transitmessage = salt + iv + encrypted;
  return transitmessage.toString();
}

function decrypt (transitmessage, pass) {
  var salt = CryptoJS.enc.Hex.parse(transitmessage.substr(0, 64));
  var iv = CryptoJS.enc.Hex.parse(transitmessage.substr(64, 32));
  var encrypted = transitmessage.substring(96);

  var key = CryptoJS.PBKDF2(pass, salt, {
      keySize: keySize/32,
      iterations: iterations
    });

  var decrypted = CryptoJS.AES.decrypt(encrypted, key, { 
    iv: iv, 
    padding: CryptoJS.pad.Pkcs7,
    mode: CryptoJS.mode.CBC

  })
  return decrypted.toString(CryptoJS.enc.Utf8);
}

使用密码：Secret Password

C＃结果：r7Oi1vMXZ5mYJay8i+slbJZEiT3CxV/1zOYntbZIsS5RuasABJKQQQVvAe50U1deIIqyQiwzQWYelMJ48WWpMQ==

Javascript结果：72ff8e7b653efbe3101d2c4ca7d7fe1af06652b907a90281aafa5ae09b45c9af091571b08d3d39cbad129939488319b2pprMQFFEJZR5JlrDsMqT8w==

结果应该是Hello World

这两种解决方案都适用于自己的环境，但是C＃或Javascript哈希值无法交换，它们不会解密。我的猜测是字符编码与它有关，因此base64大小差异如此之大。有没有人有想法让这个合作？谢谢！

Answer 1

错误发生在Javascript代码中，第一部分是Hex，而结尾是Base64中的加密结果。

以下Javascript代码使AES结果可与上面提供的C＃解决方案互换。我遇到了一些困难，确保所有结果在Hex中正确编码和解码，因此有一些新功能。

var keySize = 256;
var ivSize = 128;
var saltSize = 256;
var iterations = 1000;

var message = "Does this work?";
var password = "Secret Password";


function encrypt (msg, pass) {
  var salt = CryptoJS.lib.WordArray.random(saltSize/8);

  var key = CryptoJS.PBKDF2(pass, salt, {
      keySize: keySize/32,
      iterations: iterations
    });

  var iv = CryptoJS.lib.WordArray.random(ivSize/8);

  var encrypted = CryptoJS.AES.encrypt(msg, key, { 
    iv: iv, 
    padding: CryptoJS.pad.Pkcs7,
    mode: CryptoJS.mode.CBC

  });

    var encryptedHex = base64ToHex(encrypted.toString());
    var base64result = hexToBase64(salt + iv + encryptedHex);


  return base64result;
}

function decrypt (transitmessage, pass) {

  var hexResult = base64ToHex(transitmessage)

  var salt = CryptoJS.enc.Hex.parse(hexResult.substr(0, 64));
  var iv = CryptoJS.enc.Hex.parse(hexResult.substr(64, 32));
  var encrypted = hexToBase64(hexResult.substring(96));

  var key = CryptoJS.PBKDF2(pass, salt, {
      keySize: keySize/32,
      iterations: iterations
    });

  var decrypted = CryptoJS.AES.decrypt(encrypted, key, { 
    iv: iv, 
    padding: CryptoJS.pad.Pkcs7,
    mode: CryptoJS.mode.CBC

  })

  return decrypted.toString(CryptoJS.enc.Utf8); 
}

function hexToBase64(str) {
  return btoa(String.fromCharCode.apply(null,
    str.replace(/\r|\n/g, "").replace(/([\da-fA-F]{2}) ?/g, "0x$1 ").replace(/ +$/, "").split(" "))
  );
}

function base64ToHex(str) {
  for (var i = 0, bin = atob(str.replace(/[ \r\n]+$/, "")), hex = []; i < bin.length; ++i) {
    var tmp = bin.charCodeAt(i).toString(16);
    if (tmp.length === 1) tmp = "0" + tmp;
    hex[hex.length] = tmp;
  }
  return hex.join("");
}

Answer 2

您使用Cipher Block Chaining (CBC)模式与随机IV（正确的方式）。

在加密之前，IV将间接地影响每个明文块。因此，比较加密数据的内容对您没有帮助。

加密数据的长度也不同。我认为这是因为CryptoJS.lib.WordArray将以十六进制打印。因此，你得到十六进制编码的seed和IV以及base64编码的加密消息。

在C＃端，只有一个包含所有内容的base64编码结果。

通常，普通CBC模式不再是最先进的加密技术（例如，对于TLS1.3，已经删除了具有AES-CBC的所有密码）。在某些条件下，它可能允许某些攻击（例如填充oracle攻击）。因此，我建议使用像GCM模式这样的身份验证密码模式。