Question

下面和小提琴中的代码不适用于制作，它用于教育目的。我不想解决任何问题，因为我有一个可行的解决方案。但是，我想知道原因：

var password = "password";
var salt = Encoding.ASCII.GetBytes(password.Length.ToString());
var secret = new PasswordDeriveBytes(password, salt);

执行上述操作后，在以下方法中FixedEncryptor将起作用。

// Valid:
public static string FixedEncryptor(string content)
{
    var cipher = new RijndaelManaged();
    var plain = Encoding.Unicode.GetBytes(content);
    var key = new PasswordDeriveBytes(password, salt);
    using (var encrypt = cipher.CreateEncryptor(key.GetBytes(32), key.GetBytes(16)))
        using (var stream = new MemoryStream())
            using (var crypto = new CryptoStream(stream, encrypt, CryptoStreamMode.Write))
            {
                crypto.Write(plain, 0, plain.Length);
                crypto.FlushFinalBlock();
                return Convert.ToBase64String(stream.ToArray());
            }
}

但是，如果您实施：

var secret = new PasswordDeriveBytes("password",
     Encoding.ASCII.GetBytes("password"));

代码会突然产生：

运行时异常（第70行）：填充无效且不能   除去。

堆栈追踪：

[System.Security.Cryptography.CryptographicException：Padding is   无效，无法删除。]在Crypt.Decryptor（字符串内容）：   Program.Main（）第70行：第17行

如以下方法所示：

// Invalid:
public static string Encryptor(string content)
{
    var cipher = new RijndaelManaged();
    var plain = Encoding.Unicode.GetBytes(content);
    var key = new PasswordDeriveBytes("password", Encoding.ASCII.GetBytes("password"));
    using (var encrypt = cipher.CreateEncryptor(key.GetBytes(32), key.GetBytes(16)))
        using (var stream = new MemoryStream())
            using (var crypto = new CryptoStream(stream, encrypt, CryptoStreamMode.Write))
            {
                crypto.Write(plain, 0, plain.Length);
                crypto.FlushFinalBlock();
                return Convert.ToBase64String(stream.ToArray());
            }
}

那么为什么一个人能够成功解密，而另一个人没有正确解密并产生上述错误？

一个小例子的小提琴是here。

Answer 1

首先，生成盐的方法根本不安全;其次，PasswordDerivedBytes已被弃用，你应该关注其继任者Rfc2898DeriveBytes。

尝试以下内容 - 请注意，这需要一些using语句：System，System.IO，System.Security.Cryptography和System.Text。

只需使用Encrypt(PlainText, Password)加密数据，然后使用Decrypt(EncryptedData, Password)再次对其进行解密。 salt作为前16个字节被加载到加密数据中，并且对于每个加密/解密轮次都是完全随机的。

此代码是我自己的开源密码管理器的一部分。

/*
 * Encryption/Decryption, based on AES256 and PBKDF2
 */
public string Encrypt (string plainText, string passPhrase, bool fast_encrypt = false)
{
    string result;
    using (Rijndael algR = Rijndael.Create ()) {
        RNGCryptoServiceProvider rngC = new RNGCryptoServiceProvider ();
        byte[] iv = new byte[16];
        rngC.GetBytes (iv);
        Rfc2898DeriveBytes derived = new Rfc2898DeriveBytes (passPhrase, iv, fast_encrypt ? 10 : 3000);
        algR.KeySize = 256;
        algR.BlockSize = 128;
        algR.Key = derived.GetBytes (32);
        algR.IV = iv;
        using (MemoryStream memoryStream = new MemoryStream ()) {
            memoryStream.Write (iv, 0, 16);
            using (CryptoStream cryptoStreamEncrypt = new CryptoStream (memoryStream, algR.CreateEncryptor (algR.Key, algR.IV), CryptoStreamMode.Write)) {
                using (StreamWriter streamWriterEncrypt = new StreamWriter (cryptoStreamEncrypt)) {
                    streamWriterEncrypt.Write (plainText);
                }
            }

            result = Convert.ToBase64String (memoryStream.ToArray ());
        }
    }

    return result;
}

public string Decrypt (string cipherText, string passPhrase, bool fast_decrypt = false)
{
    string result;
    using (Rijndael algR = Rijndael.Create ()) {
        using (MemoryStream memoryStream = new MemoryStream (Convert.FromBase64String (cipherText))) {
            byte[] iv = new byte[16];
            memoryStream.Read (iv, 0, 16);
            Rfc2898DeriveBytes derived = new Rfc2898DeriveBytes (passPhrase, iv, fast_decrypt ? 10 : 3000);
            algR.KeySize = 256;
            algR.BlockSize = 128;
            algR.Key = derived.GetBytes (32);
            algR.IV = iv;
            using (CryptoStream cryptoStreamDecrypt = new CryptoStream (memoryStream, algR.CreateDecryptor (algR.Key, algR.IV), CryptoStreamMode.Read)) {
                using (StreamReader streamReaderDecrypt = new StreamReader (cryptoStreamDecrypt)) {
                    result = streamReaderDecrypt.ReadToEnd ();
                }
            }
        }
    }

    return result;
}

Answer 2

从您发布的代码示例中，您的问题来自于您使用两种不同的盐。

在FixedEncryptor中，您使用

的盐

Encoding.ASCII.GetBytes(password.Length.ToString());

编码为等于{ 56 }的字节数组，这是因为Length返回8然后调用ToString（），返回字符串“8”，您将其转换为ascii值56。

在加密器中，您使用

的盐

Encoding.ASCII.GetBytes("password")

编码为一个等于{ 112, 97, 115, 115, 119, 111, 114, 100}的字节数组，它是字符“p”，“a”，“s”，“s”，“w”，“o”的ascii值， “r”和“d”。

您遇到的问题是您只是尝试在解密功能中使用{ 56 }，因此您的问题归结为您的加密功能，而您的解密功能使用两种不同的盐

如果我创建一个新的Decrypter以使用与Encryptor相同的盐和密码，那么单独FixedDecryptor以匹配FixedEncryptor的盐，一切都会有效细

public class Program
{
    public static void Main()
    {
        var message = "Hello World!";
        var fixedCipherText = Crypt.FixedEncryptor(message);
        var cipherText = Crypt.Encryptor(message);
        Console.WriteLine(cipherText);
        Console.WriteLine(fixedCipherText);
        var plainText = Crypt.Decryptor(cipherText);
        var fixedPlainText = Crypt.FixedDecryptor(fixedCipherText);
        Console.WriteLine(plainText);
        Console.WriteLine(fixedPlainText);
    }
}

public static class Crypt
{
    private const string password = "password";
    private readonly static byte[] salt = Encoding.ASCII.GetBytes(password.Length.ToString());
    public static string FixedEncryptor(string content)
    {
        var cipher = new RijndaelManaged();
        var plain = Encoding.Unicode.GetBytes(content);
        var key = new PasswordDeriveBytes(password, salt);
        using (var encrypt = cipher.CreateEncryptor(key.GetBytes(32), key.GetBytes(16)))
        using (var stream = new MemoryStream())
        using (var crypto = new CryptoStream(stream, encrypt, CryptoStreamMode.Write))
        {
            crypto.Write(plain, 0, plain.Length);
            crypto.FlushFinalBlock();
            return Convert.ToBase64String(stream.ToArray());
        }
    }

    public static string Encryptor(string content)
    {
        var cipher = new RijndaelManaged();
        var plain = Encoding.Unicode.GetBytes(content);
        var key = new PasswordDeriveBytes("password", Encoding.ASCII.GetBytes("password"));
        using (var encrypt = cipher.CreateEncryptor(key.GetBytes(32), key.GetBytes(16)))
        using (var stream = new MemoryStream())
        using (var crypto = new CryptoStream(stream, encrypt, CryptoStreamMode.Write))
        {
            crypto.Write(plain, 0, plain.Length);
            crypto.FlushFinalBlock();
            return Convert.ToBase64String(stream.ToArray());
        }
    }

    public static string FixedDecryptor(string content)
    {
        var cipher = new RijndaelManaged();
        var encrypted = Convert.FromBase64String(content);
        var key = new PasswordDeriveBytes(password, salt);
        using (var decryptor = cipher.CreateDecryptor(key.GetBytes(32), key.GetBytes(16)))
        using (var stream = new MemoryStream(encrypted))
        using (var crypto = new CryptoStream(stream, decryptor, CryptoStreamMode.Read))
        {
            byte[] plain = new byte[encrypted.Length];
            int decrypted = crypto.Read(plain, 0, plain.Length);
            string data = Encoding.Unicode.GetString(plain, 0, decrypted);
            return data;
        }
    }

    public static string Decryptor(string content)
    {
        var cipher = new RijndaelManaged();
        var encrypted = Convert.FromBase64String(content);
        var key = new PasswordDeriveBytes("password", Encoding.ASCII.GetBytes("password"));
        using (var decryptor = cipher.CreateDecryptor(key.GetBytes(32), key.GetBytes(16)))
        using (var stream = new MemoryStream(encrypted))
        using (var crypto = new CryptoStream(stream, decryptor, CryptoStreamMode.Read))
        {
            byte[] plain = new byte[encrypted.Length];
            int decrypted = crypto.Read(plain, 0, plain.Length);
            string data = Encoding.Unicode.GetString(plain, 0, decrypted);
            return data;
        }
    }
}

Fiddel代码。

然而，这仍然不是“正确”做事的方式。请参阅Sine Nomen's回答

Salt中的内容导致它在解密时失败

2 个答案: