在C#中加密和解密字符串

Question

在C#中满足以下内容的最现代(最佳)方式是什么？

string encryptedString = SomeStaticClass.Encrypt(sourceString);

string decryptedString = SomeStaticClass.Decrypt(encryptedString);

但最小的涉及盐,键,与字节[]等混乱的大惊小怪等.

谷歌搜索和混淆我发现的东西(你可以看到类似的SO Q列表,看这是一个欺骗性的问题).

Answer 1

更新2015年12月23日:由于这个答案似乎得到了很多赞成,我已经更新它以修复愚蠢的错误,并根据评论和反馈大致改进代码.有关具体改进的列表,请参阅帖子末尾.

正如其他人所说,密码学并不简单,所以最好避免"滚动自己的"加密算法.

但是,你可以在内置的RijndaelManaged加密类之类的"滚动你自己的"包装类.

Rijndael是当前高级加密标准的算法名称,因此您肯定使用的算法可被视为"最佳实践".

该RijndaelManaged班的确通常需要你"渣土约"使用字节数组,盐,钥匙,初始化向量等,但这恰恰是一种具体的,可有些抽象掉你的"包装"类中.

下面的类是一个我写了前一阵子执行完全相同你后之类的话,简单的单一方法调用,让一些基于字符串的明文与基于字符串的密码进行加密,用得到的加密字符串也被表示为一个字符串.当然,有一种等效方法可以用相同的密码解密加密的字符串.

与此代码的第一个版本不同,每次使用完全相同的salt和IV值时,这个较新的版本每次都会生成随机的salt和IV值.由于在给定字符串的加密和解密之间盐和IV必须相同,因此在加密时将盐和IV预先加密到密文,并再次从密码中提取以便执行解密.结果是,用完全相同的密码加密完全相同的明文,每次都会产生完全不同的密文结果.

在使用这种"实力"来自使用RijndaelManaged类来执行加密的你,与使用沿着Rfc2898DeriveBytes的功能System.Security.Cryptography,这将产生使用标准和安全算法(具体地讲,您的加密密钥的命名空间PBKDF2基于与字符串)您提供的基于密码.(注意,这是对第一个版本使用旧版PBKDF1算法的改进).

最后,重要的是要注意这仍然是未经身份验证的加密.仅加密仅提供隐私(即第三方不知道消息),而经认证的加密旨在提供隐私和真实性(即,接收者知道消息是由发送者发送的).

在不知道您的确切要求的情况下,很难说这里的代码是否足够安全以满足您的需求,但是,它的生成是为了在实现的相对简单性与"质量"之间实现良好的平衡.例如,如果加密字符串的"接收者"直接从受信任的"发件人"接收字符串,则甚至可能不需要身份验证.

如果您需要更复杂的东西,并提供经过身份验证的加密,请查看此帖子以了解实施情况.

这是代码:

using System;
using System.Text;
using System.Security.Cryptography;
using System.IO;
using System.Linq;

namespace EncryptStringSample
{
    public static class StringCipher
    {
        // This constant is used to determine the keysize of the encryption algorithm in bits.
        // We divide this by 8 within the code below to get the equivalent number of bytes.
        private const int Keysize = 256;

        // This constant determines the number of iterations for the password bytes generation function.
        private const int DerivationIterations = 1000;

        public static string Encrypt(string plainText, string passPhrase)
        {
            // Salt and IV is randomly generated each time, but is preprended to encrypted cipher text
            // so that the same Salt and IV values can be used when decrypting.  
            var saltStringBytes = Generate256BitsOfRandomEntropy();
            var ivStringBytes = Generate256BitsOfRandomEntropy();
            var plainTextBytes = Encoding.UTF8.GetBytes(plainText);
            using (var password = new Rfc2898DeriveBytes(passPhrase, saltStringBytes, DerivationIterations))
            {
                var keyBytes = password.GetBytes(Keysize / 8);
                using (var symmetricKey = new RijndaelManaged())
                {
                    symmetricKey.BlockSize = 256;
                    symmetricKey.Mode = CipherMode.CBC;
                    symmetricKey.Padding = PaddingMode.PKCS7;
                    using (var encryptor = symmetricKey.CreateEncryptor(keyBytes, ivStringBytes))
                    {
                        using (var memoryStream = new MemoryStream())
                        {
                            using (var cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
                            {
                                cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
                                cryptoStream.FlushFinalBlock();
                                // Create the final bytes as a concatenation of the random salt bytes, the random iv bytes and the cipher bytes.
                                var cipherTextBytes = saltStringBytes;
                                cipherTextBytes = cipherTextBytes.Concat(ivStringBytes).ToArray();
                                cipherTextBytes = cipherTextBytes.Concat(memoryStream.ToArray()).ToArray();
                                memoryStream.Close();
                                cryptoStream.Close();
                                return Convert.ToBase64String(cipherTextBytes);
                            }
                        }
                    }
                }
            }
        }

        public static string Decrypt(string cipherText, string passPhrase)
        {
            // Get the complete stream of bytes that represent:
            // [32 bytes of Salt] + [32 bytes of IV] + [n bytes of CipherText]
            var cipherTextBytesWithSaltAndIv = Convert.FromBase64String(cipherText);
            // Get the saltbytes by extracting the first 32 bytes from the supplied cipherText bytes.
            var saltStringBytes = cipherTextBytesWithSaltAndIv.Take(Keysize / 8).ToArray();
            // Get the IV bytes by extracting the next 32 bytes from the supplied cipherText bytes.
            var ivStringBytes = cipherTextBytesWithSaltAndIv.Skip(Keysize / 8).Take(Keysize / 8).ToArray();
            // Get the actual cipher text bytes by removing the first 64 bytes from the cipherText string.
            var cipherTextBytes = cipherTextBytesWithSaltAndIv.Skip((Keysize / 8) * 2).Take(cipherTextBytesWithSaltAndIv.Length - ((Keysize / 8) * 2)).ToArray();

            using (var password = new Rfc2898DeriveBytes(passPhrase, saltStringBytes, DerivationIterations))
            {
                var keyBytes = password.GetBytes(Keysize / 8);
                using (var symmetricKey = new RijndaelManaged())
                {
                    symmetricKey.BlockSize = 256;
                    symmetricKey.Mode = CipherMode.CBC;
                    symmetricKey.Padding = PaddingMode.PKCS7;
                    using (var decryptor = symmetricKey.CreateDecryptor(keyBytes, ivStringBytes))
                    {
                        using (var memoryStream = new MemoryStream(cipherTextBytes))
                        {
                            using (var cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read))
                            {
                                var plainTextBytes = new byte[cipherTextBytes.Length];
                                var decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
                                memoryStream.Close();
                                cryptoStream.Close();
                                return Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount);
                            }
                        }
                    }
                }
            }
        }

        private static byte[] Generate256BitsOfRandomEntropy()
        {
            var randomBytes = new byte[32]; // 32 Bytes will give us 256 bits.
            using (var rngCsp = new RNGCryptoServiceProvider())
            {
                // Fill the array with cryptographically secure random bytes.
                rngCsp.GetBytes(randomBytes);
            }
            return randomBytes;
        }
    }
}

上面的类可以非常简单地使用类似于以下的代码:

using System;

namespace EncryptStringSample
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Please enter a password to use:");
            string password = Console.ReadLine();
            Console.WriteLine("Please enter a string to encrypt:");
            string plaintext = Console.ReadLine();
            Console.WriteLine("");

            Console.WriteLine("Your encrypted string is:");
            string encryptedstring = StringCipher.Encrypt(plaintext, password);
            Console.WriteLine(encryptedstring);
            Console.WriteLine("");

            Console.WriteLine("Your decrypted string is:");
            string decryptedstring = StringCipher.Decrypt(encryptedstring, password);
            Console.WriteLine(decryptedstring);
            Console.WriteLine("");

            Console.WriteLine("Press any key to exit...");
            Console.ReadLine();
        }
    }
}

(你可以下载一个简单的VS2013样品溶液(其中包括一些单元测试)在这里).

更新2015年12月23日: 代码的具体改进列表如下:

• 修复了加密和解密之间编码不同的愚蠢错误.由于生成盐和IV值的机制已经改变,因此不再需要编码.
• 由于salt/IV更改,以前的代码注释错误地指示UTF8编码16个字符的字符串产生32个字节不再适用(因为不再需要编码).
• 已取代的PBKDF1算法的使用已被更现代的PBKDF2算法的使用所取代.
• 密码推导现在已经被正确腌制了,而之前它根本没有被腌制(另一个愚蠢的小虫被压扁).

Answer 2

using System.IO;
using System.Text;
using System.Security.Cryptography;

public static class EncryptionHelper
{
    public static string Encrypt(string clearText)
    {
        string EncryptionKey = "abc123";
        byte[] clearBytes = Encoding.Unicode.GetBytes(clearText);
        using (Aes encryptor = Aes.Create())
        {
            Rfc2898DeriveBytes pdb = new Rfc2898DeriveBytes(EncryptionKey, new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
            encryptor.Key = pdb.GetBytes(32);
            encryptor.IV = pdb.GetBytes(16);
            using (MemoryStream ms = new MemoryStream())
            {
                using (CryptoStream cs = new CryptoStream(ms, encryptor.CreateEncryptor(), CryptoStreamMode.Write))
                {
                    cs.Write(clearBytes, 0, clearBytes.Length);
                    cs.Close();
                }
                clearText = Convert.ToBase64String(ms.ToArray());
            }
        }
        return clearText;
    }
    public static string Decrypt(string cipherText)
    {
        string EncryptionKey = "abc123";
        cipherText = cipherText.Replace(" ", "+");
        byte[] cipherBytes = Convert.FromBase64String(cipherText);
        using (Aes encryptor = Aes.Create())
        {
            Rfc2898DeriveBytes pdb = new Rfc2898DeriveBytes(EncryptionKey, new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
            encryptor.Key = pdb.GetBytes(32);
            encryptor.IV = pdb.GetBytes(16);
            using (MemoryStream ms = new MemoryStream())
            {
                using (CryptoStream cs = new CryptoStream(ms, encryptor.CreateDecryptor(), CryptoStreamMode.Write))
                {
                    cs.Write(cipherBytes, 0, cipherBytes.Length);
                    cs.Close();
                }
                cipherText = Encoding.Unicode.GetString(ms.ToArray());
            }
        }
        return cipherText;
    }
}

Answer 3

试试这堂课:

public class DataEncryptor
{
    TripleDESCryptoServiceProvider symm;

    #region Factory
    public DataEncryptor()
    {
        this.symm = new TripleDESCryptoServiceProvider();
        this.symm.Padding = PaddingMode.PKCS7;
    }
    public DataEncryptor(TripleDESCryptoServiceProvider keys)
    {
        this.symm = keys;
    }

    public DataEncryptor(byte[] key, byte[] iv)
    {
        this.symm = new TripleDESCryptoServiceProvider();
        this.symm.Padding = PaddingMode.PKCS7;
        this.symm.Key = key;
        this.symm.IV = iv;
    }

    #endregion

    #region Properties
    public TripleDESCryptoServiceProvider Algorithm
    {
        get { return symm; }
        set { symm = value; }
    }
    public byte[] Key
    {
        get { return symm.Key; }
        set { symm.Key = value; }
    }
    public byte[] IV
    {
        get { return symm.IV; }
        set { symm.IV = value; }
    }

    #endregion

    #region Crypto

    public byte[] Encrypt(byte[] data) { return Encrypt(data, data.Length); }
    public byte[] Encrypt(byte[] data, int length)
    {
        try
        {
            // Create a MemoryStream.
            var ms = new MemoryStream();

            // Create a CryptoStream using the MemoryStream 
            // and the passed key and initialization vector (IV).
            var cs = new CryptoStream(ms,
                symm.CreateEncryptor(symm.Key, symm.IV),
                CryptoStreamMode.Write);

            // Write the byte array to the crypto stream and flush it.
            cs.Write(data, 0, length);
            cs.FlushFinalBlock();

            // Get an array of bytes from the 
            // MemoryStream that holds the 
            // encrypted data.
            byte[] ret = ms.ToArray();

            // Close the streams.
            cs.Close();
            ms.Close();

            // Return the encrypted buffer.
            return ret;
        }
        catch (CryptographicException ex)
        {
            Console.WriteLine("A cryptographic error occured: {0}", ex.Message);
        }
        return null;
    }

    public string EncryptString(string text)
    {
        return Convert.ToBase64String(Encrypt(Encoding.UTF8.GetBytes(text)));
    }

    public byte[] Decrypt(byte[] data) { return Decrypt(data, data.Length); }
    public byte[] Decrypt(byte[] data, int length)
    {
        try
        {
            // Create a new MemoryStream using the passed 
            // array of encrypted data.
            MemoryStream ms = new MemoryStream(data);

            // Create a CryptoStream using the MemoryStream 
            // and the passed key and initialization vector (IV).
            CryptoStream cs = new CryptoStream(ms,
                symm.CreateDecryptor(symm.Key, symm.IV),
                CryptoStreamMode.Read);

            // Create buffer to hold the decrypted data.
            byte[] result = new byte[length];

            // Read the decrypted data out of the crypto stream
            // and place it into the temporary buffer.
            cs.Read(result, 0, result.Length);
            return result;
        }
        catch (CryptographicException ex)
        {
            Console.WriteLine("A cryptographic error occured: {0}", ex.Message);
        }
        return null;
    }

    public string DecryptString(string data)
    {
        return Encoding.UTF8.GetString(Decrypt(Convert.FromBase64String(data))).TrimEnd('\0');
    }

    #endregion

}

并像这样使用它:

string message="A very secret message here.";
DataEncryptor keys=new DataEncryptor();
string encr=keys.EncryptString(message);

// later
string actual=keys.DecryptString(encr);

Answer 4

如果您需要在内存中存储密码并希望加密,则应使用SecureString:

http://msdn.microsoft.com/en-us/library/system.security.securestring.aspx

对于更一般的用途,我会使用FIPS认可的算法,例如Advanced Encryption Standard,以前称为Rijndael.有关实现示例,请参阅此页面:

http://msdn.microsoft.com/en-us/library/system.security.cryptography.rijndael.aspx

Answer 5

如果您的目标是不支持的ASP.NET Core,则RijndaelManaged可以使用IDataProtectionProvider.

首先,配置您的应用程序以使用数据保护:

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddDataProtection();
    }
    // ...
}

然后,您将能够注入IDataProtectionProvider实例并使用它来加密/解密数据:

public class MyService : IService
{
    private const string Purpose = "my protection purpose";
    private readonly IDataProtectionProvider _provider;

    public MyService(IDataProtectionProvider provider)
    {
        _provider = provider;
    }

    public string Encrypt(string plainText)
    {
        var protector = _provider.CreateProtector(Purpose);
        return protector.Protect(plainText);
    }

    public string Decrypt(string cipherText)
    {
        var protector = _provider.CreateProtector(Purpose);
        return protector.Unprotect(cipherText);
    }
}

有关详细信息,请参阅此文章.

Answer 6

您可能正在寻找ProtectedData使用用户的登录凭据加密数据的类.