这是一个简单的Snippet，最初由ASP Snippet编写

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


 private string Encrypt(string clearText)
    {
        string EncryptionKey = "yourkey";
        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;
    }

 private string Decrypt(string cipherText)
    {
        string EncryptionKey = "yourkey";
        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;
    }

下面的代码是Ghazal回答类似问题的改进版本。

public class EncryptionHelper
{
    private Aes aesEncryptor;

    public EncryptionHelper()
    {
    }

    private void BuildAesEncryptor(string key)
    {
        aesEncryptor = Aes.Create();
        var pdb = new Rfc2898DeriveBytes(key, new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
        aesEncryptor.Key = pdb.GetBytes(32);
        aesEncryptor.IV = pdb.GetBytes(16);
    }

    public string EncryptString(string clearText, string key)
    {
        BuildAesEncryptor(key);
        var clearBytes = Encoding.Unicode.GetBytes(clearText);
        using (var ms = new MemoryStream())
        {
            using (var cs = new CryptoStream(ms, aesEncryptor.CreateEncryptor(), CryptoStreamMode.Write))
            {
                cs.Write(clearBytes, 0, clearBytes.Length);
            }
            var encryptedText = Convert.ToBase64String(ms.ToArray());
            return encryptedText;
        }
    }

    public string DecryptString(string cipherText, string key)
    {
        BuildAesEncryptor(key);
        cipherText = cipherText.Replace(" ", "+");
        var cipherBytes = Convert.FromBase64String(cipherText);
        using (var ms = new MemoryStream())
        {
            using (var cs = new CryptoStream(ms, aesEncryptor.CreateDecryptor(), CryptoStreamMode.Write))
            {
                cs.Write(cipherBytes, 0, cipherBytes.Length);
            }
            var clearText = Encoding.Unicode.GetString(ms.ToArray());
            return clearText;
        }
    }
}

下面的示例演示如何加密和解密示例数据:

    // 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 = 128;

    // 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 = GenerateBitsOfRandomEntropy(16);
        var ivStringBytes = GenerateBitsOfRandomEntropy(16);
        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 = 128;
                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 = 128;
                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[] GenerateBitsOfRandomEntropy(int size)
    {
        // 32 Bytes will give us 256 bits.
        // 16 Bytes will give us 128 bits.
        var randomBytes = new byte[size]; 
        using (var rngCsp = new RNGCryptoServiceProvider())
        {
            // Fill the array with cryptographically secure random bytes.
            rngCsp.GetBytes(randomBytes);
        }
        return randomBytes;
    }

下面是一个使用RSA的例子。

重要:使用RSA加密KeySize - MinimumPadding加密的数据大小是有限制的。例如256字节(假设2048位密钥)- 42字节(最小OEAP填充)= 214字节(最大明文大小)

用RSA密钥替换your_rsa_key。

var provider = new System.Security.Cryptography.RSACryptoServiceProvider();
provider.ImportParameters(your_rsa_key);

var encryptedBytes = provider.Encrypt(
    System.Text.Encoding.UTF8.GetBytes("Hello World!"), true);

string decryptedTest = System.Text.Encoding.UTF8.GetString(
    provider.Decrypt(encryptedBytes, true));

更多信息，请访问MSDN - RSACryptoServiceProvider

为了简单起见，我为自己做了这个函数，用于非加密目的:用你的密码替换“yourpassphrase”…

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

 namespace My
{
    public class strCrypto
    {
        // This constant string is used as a "salt" value for the PasswordDeriveBytes function calls.
    // This size of the IV (in bytes) must = (keysize / 8).  Default keysize is 256, so the IV must be
    // 32 bytes long.  Using a 16 character string here gives us 32 bytes when converted to a byte array.
    private const string initVector = "r5dm5fgm24mfhfku";
    private const string passPhrase = "yourpassphrase"; // email password encryption password

    // This constant is used to determine the keysize of the encryption algorithm.
    private const int keysize = 256;

    public static string encryptString(string plainText)
    {
        //if the plaintext  is empty or null string just return an empty string
        if (plainText == "" || plainText == null )
        {
            return "";
        }

        byte[] initVectorBytes = Encoding.UTF8.GetBytes(initVector);
        byte[] plainTextBytes = Encoding.UTF8.GetBytes(plainText);
        PasswordDeriveBytes password = new PasswordDeriveBytes(passPhrase, null);
        byte[] keyBytes = password.GetBytes(keysize / 8);
        RijndaelManaged symmetricKey = new RijndaelManaged();
        symmetricKey.Mode = CipherMode.CBC;
        ICryptoTransform encryptor = symmetricKey.CreateEncryptor(keyBytes, initVectorBytes);
        MemoryStream memoryStream = new MemoryStream();
        CryptoStream cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write);
        cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
        cryptoStream.FlushFinalBlock();
        byte[] cipherTextBytes = memoryStream.ToArray();
        memoryStream.Close();
        cryptoStream.Close();
        return Convert.ToBase64String(cipherTextBytes);
    }

    public static string decryptString(string cipherText)
    {
        //if the ciphertext is empty or null string just return an empty string
        if (cipherText == "" || cipherText == null )
        {
            return "";
        }

        byte[] initVectorBytes = Encoding.ASCII.GetBytes(initVector);
        byte[] cipherTextBytes = Convert.FromBase64String(cipherText);
        PasswordDeriveBytes password = new PasswordDeriveBytes(passPhrase, null);
        byte[] keyBytes = password.GetBytes(keysize / 8);
        RijndaelManaged symmetricKey = new RijndaelManaged();
        symmetricKey.Mode = CipherMode.CBC;
        ICryptoTransform decryptor = symmetricKey.CreateDecryptor(keyBytes, initVectorBytes);
        MemoryStream memoryStream = new MemoryStream(cipherTextBytes);
        CryptoStream cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read);
        byte[] plainTextBytes = new byte[cipherTextBytes.Length];
        int decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
        memoryStream.Close();
        cryptoStream.Close();
        return Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount);
    }


}

}

很好的例子如何做到这一点使用PGPCore与BouncyCastle，非常简单的解决方案:https://blog.bitscry.com/2018/07/05/pgp-encryption-and-decryption-in-c/

我尝试了不同的解决方案，但这对我来说是最好的，有些bug，但这是完美的。

using (PGP pgp = new PGP())
{
// Generate keys
pgp.GenerateKey(@"C:\TEMP\keys\public.asc", @"C:\TEMP\keys\private.asc", "email@email.com", "password");
// Encrypt file
pgp.EncryptFile(@"C:\TEMP\keys\content.txt", @"C:\TEMP\keys\content__encrypted.pgp", @"C:\TEMP\keys\public.asc", true, true);
// Encrypt and sign file
pgp.EncryptFileAndSign(@"C:\TEMP\keys\content.txt", @"C:\TEMP\keys\content__encrypted_signed.pgp", @"C:\TEMP\keys\public.asc", @"C:\TEMP\keys\private.asc", "password", true, true);
// Decrypt file
pgp.DecryptFile(@"C:\TEMP\keys\content__encrypted.pgp", @"C:\TEMP\keys\content__decrypted.txt", @"C:\TEMP\keys\private.asc", "password");
// Decrypt signed file
pgp.DecryptFile(@"C:\TEMP\keys\content__encrypted_signed.pgp", @"C:\TEMP\keys\content__decrypted_signed.txt", @"C:\TEMP\keys\private.asc", "password");

// Encrypt stream
using (FileStream inputFileStream = new FileStream(@"C:\TEMP\keys\content.txt", FileMode.Open))
using (Stream outputFileStream = File.Create(@"C:\TEMP\keys\content__encrypted2.pgp"))
using (Stream publicKeyStream = new FileStream(@"C:\TEMP\keys\public.asc", FileMode.Open))
    pgp.EncryptStream(inputFileStream, outputFileStream, publicKeyStream, true, true);

// Decrypt stream
using (FileStream inputFileStream = new FileStream(@"C:\TEMP\keys\content__encrypted2.pgp", FileMode.Open))
using (Stream outputFileStream = File.Create(@"C:\TEMP\keys\content__decrypted2.txt"))
using (Stream privateKeyStream = new FileStream(@"C:\TEMP\keys\private.asc", FileMode.Open))
    pgp.DecryptStream(inputFileStream, outputFileStream, privateKeyStream, "password");
}