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

我在这里复制了一个类似问题的答案:c#的简单双向加密。

基于多个答案和评论。

加密文本前的随机初始化向量(@jbtule) 使用TransformFinalBlock()代替MemoryStream (@RenniePet) 没有预填充键，以避免任何人复制和粘贴灾难 正确处理和使用模式

代码:

/// <summary>
/// Simple encryption/decryption using a random initialization vector
/// and prepending it to the crypto text.
/// </summary>
/// <remarks>Based on multiple answers in https://stackoverflow.com/questions/165808/simple-two-way-encryption-for-c-sharp </remarks>
public class SimpleAes : IDisposable
{
    /// <summary>
    ///     Initialization vector length in bytes.
    /// </summary>
    private const int IvBytes = 16;

    /// <summary>
    ///     Must be exactly 16, 24 or 32 characters long.
    /// </summary>
    private static readonly byte[] Key = Convert.FromBase64String("FILL ME WITH 16, 24 OR 32 CHARS");

    private readonly UTF8Encoding _encoder;
    private readonly ICryptoTransform _encryptor;
    private readonly RijndaelManaged _rijndael;

    public SimpleAes()
    {
        _rijndael = new RijndaelManaged {Key = Key};
        _rijndael.GenerateIV();
        _encryptor = _rijndael.CreateEncryptor();
        _encoder = new UTF8Encoding();
    }

    public string Decrypt(string encrypted)
    {
        return _encoder.GetString(Decrypt(Convert.FromBase64String(encrypted)));
    }

    public void Dispose()
    {
        _rijndael.Dispose();
        _encryptor.Dispose();
    }

    public string Encrypt(string unencrypted)
    {
        return Convert.ToBase64String(Encrypt(_encoder.GetBytes(unencrypted)));
    }

    private byte[] Decrypt(byte[] buffer)
    {
        // IV is prepended to cryptotext
        byte[] iv = buffer.Take(IvBytes).ToArray();
        using (ICryptoTransform decryptor = _rijndael.CreateDecryptor(_rijndael.Key, iv))
        {
            return decryptor.TransformFinalBlock(buffer, IvBytes, buffer.Length - IvBytes);
        }
    }

    private byte[] Encrypt(byte[] buffer)
    {
        // Prepend cryptotext with IV
        byte[] inputBuffer = _rijndael.IV.Concat(buffer).ToArray();
        return _encryptor.TransformFinalBlock(inputBuffer, IvBytes, buffer.Length);
    }
}

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

加密是编程中非常常见的问题。我认为最好是安装一个包来为您做这个任务。也许是一个简单的开源NuGet项目 简单Aes加密

密钥在配置文件中，因此很容易在生产环境中更改，而且我没有看到任何缺点。

<MessageEncryption>
  <EncryptionKey KeySize="256" Key="3q2+796tvu/erb7v3q2+796tvu/erb7v3q2+796tvu8="/>
</MessageEncryption>

            using System;
            using System.Collections.Generic;
            using System.Text;
            using System.Text.RegularExpressions;  // This is for password validation
            using System.Security.Cryptography;
            using System.Configuration;  // This is where the hash functions reside

            namespace BullyTracker.Common
            {
                public class HashEncryption
                {
                    //public string GenerateHashvalue(string thisPassword)
                    //{
                    //    MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
                    //    byte[] tmpSource;
                    //    byte[] tmpHash;

                    //    tmpSource = ASCIIEncoding.ASCII.GetBytes(thisPassword); // Turn password into byte array
                    //    tmpHash = md5.ComputeHash(tmpSource);

                    //    StringBuilder sOutput = new StringBuilder(tmpHash.Length);
                    //    for (int i = 0; i < tmpHash.Length; i++)
                    //    {
                    //        sOutput.Append(tmpHash[i].ToString("X2"));  // X2 formats to hexadecimal
                    //    }
                    //    return sOutput.ToString();
                    //}
                    //public Boolean VerifyHashPassword(string thisPassword, string thisHash)
                    //{
                    //    Boolean IsValid = false;
                    //    string tmpHash = GenerateHashvalue(thisPassword); // Call the routine on user input
                    //    if (tmpHash == thisHash) IsValid = true;  // Compare to previously generated hash
                    //    return IsValid;
                    //}
                    public string GenerateHashvalue(string toEncrypt, bool useHashing)
                    {
                        byte[] keyArray;
                        byte[] toEncryptArray = UTF8Encoding.UTF8.GetBytes(toEncrypt);

                        System.Configuration.AppSettingsReader settingsReader = new AppSettingsReader();
                        // Get the key from config file
                        string key = (string)settingsReader.GetValue("SecurityKey", typeof(String));
                        //System.Windows.Forms.MessageBox.Show(key);
                        if (useHashing)
                        {
                            MD5CryptoServiceProvider hashmd5 = new MD5CryptoServiceProvider();
                            keyArray = hashmd5.ComputeHash(UTF8Encoding.UTF8.GetBytes(key));
                            hashmd5.Clear();
                        }
                        else
                            keyArray = UTF8Encoding.UTF8.GetBytes(key);

                        TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
                        tdes.Key = keyArray;
                        tdes.Mode = CipherMode.ECB;
                        tdes.Padding = PaddingMode.PKCS7;

                        ICryptoTransform cTransform = tdes.CreateEncryptor();
                        byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);
                        tdes.Clear();
                        return Convert.ToBase64String(resultArray, 0, resultArray.Length);
                    }
                    /// <summary>
                    /// DeCrypt a string using dual encryption method. Return a DeCrypted clear string
                    /// </summary>
                    /// <param name="cipherString">encrypted string</param>
                    /// <param name="useHashing">Did you use hashing to encrypt this data? pass true is yes</param>
                    /// <returns></returns>
                    public string Decrypt(string cipherString, bool useHashing)
                    {
                        byte[] keyArray;
                        byte[] toEncryptArray = Convert.FromBase64String(cipherString);

                        System.Configuration.AppSettingsReader settingsReader = new AppSettingsReader();
                        //Get your key from config file to open the lock!
                        string key = (string)settingsReader.GetValue("SecurityKey", typeof(String));

                        if (useHashing)
                        {
                            MD5CryptoServiceProvider hashmd5 = new MD5CryptoServiceProvider();
                            keyArray = hashmd5.ComputeHash(UTF8Encoding.UTF8.GetBytes(key));
                            hashmd5.Clear();
                        }
                        else
                            keyArray = UTF8Encoding.UTF8.GetBytes(key);

                        TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
                        tdes.Key = keyArray;
                        tdes.Mode = CipherMode.ECB;
                        tdes.Padding = PaddingMode.PKCS7;

                        ICryptoTransform cTransform = tdes.CreateDecryptor();
                        byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);

                        tdes.Clear();
                        return UTF8Encoding.UTF8.GetString(resultArray);
                    }


                }

            }

这是布雷特安排在这里的课程。然而，我做了一个轻微的编辑，因为我在使用URL字符串加密和解密时收到了错误“无效的长度为一个Base-64字符数组”。

public class CryptoURL
{
    private static byte[] _salt = Encoding.ASCII.GetBytes("Catto_Salt_Enter_Any_Value99");

    /// <summary>
    /// Encrypt the given string using AES.  The string can be decrypted using 
    /// DecryptStringAES().  The sharedSecret parameters must match. 
    /// The SharedSecret for the Password Reset that is used is in the next line
    ///  string sharedSecret = "OneUpSharedSecret9";
    /// </summary>
    /// <param name="plainText">The text to encrypt.</param>
    /// <param name="sharedSecret">A password used to generate a key for encryption.</param>
    public static string EncryptString(string plainText, string sharedSecret)
    {
        if (string.IsNullOrEmpty(plainText))
            throw new ArgumentNullException("plainText");
        if (string.IsNullOrEmpty(sharedSecret))
            throw new ArgumentNullException("sharedSecret");

        string outStr = null;                       // Encrypted string to return
        RijndaelManaged aesAlg = null;              // RijndaelManaged object used to encrypt the data.

        try
        {
            // generate the key from the shared secret and the salt
            Rfc2898DeriveBytes key = new Rfc2898DeriveBytes(sharedSecret, _salt);

            // Create a RijndaelManaged object
            aesAlg = new RijndaelManaged();
            aesAlg.Key = key.GetBytes(aesAlg.KeySize / 8);

            // Create a decryptor to perform the stream transform.
            ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);

            // Create the streams used for encryption.
            using (MemoryStream msEncrypt = new MemoryStream())
            {
                // prepend the IV
                msEncrypt.Write(BitConverter.GetBytes(aesAlg.IV.Length), 0, sizeof(int));
                msEncrypt.Write(aesAlg.IV, 0, aesAlg.IV.Length);
                using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                {
                    using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                    {
                        //Write all data to the stream.
                        swEncrypt.Write(plainText);
                    }
                }

                outStr = HttpServerUtility.UrlTokenEncode(msEncrypt.ToArray());
                //outStr = Convert.ToBase64String(msEncrypt.ToArray());
                // you may need to add a reference. right click reference in solution explorer => "add Reference" => .NET tab => select "System.Web"
            }
        }
        finally
        {
            // Clear the RijndaelManaged object.
            if (aesAlg != null)
                aesAlg.Clear();
        }

        // Return the encrypted bytes from the memory stream.
        return outStr;
    }

    /// <summary>
    /// Decrypt the given string.  Assumes the string was encrypted using 
    /// EncryptStringAES(), using an identical sharedSecret.
    /// </summary>
    /// <param name="cipherText">The text to decrypt.</param>
    /// <param name="sharedSecret">A password used to generate a key for decryption.</param>
    public static string DecryptString(string cipherText, string sharedSecret)
    {
        if (string.IsNullOrEmpty(cipherText))
            throw new ArgumentNullException("cipherText");
        if (string.IsNullOrEmpty(sharedSecret))
            throw new ArgumentNullException("sharedSecret");

        // Declare the RijndaelManaged object
        // used to decrypt the data.
        RijndaelManaged aesAlg = null;

        // Declare the string used to hold
        // the decrypted text.
        string plaintext = null;

        byte[] inputByteArray;

        try
        {
            // generate the key from the shared secret and the salt
            Rfc2898DeriveBytes key = new Rfc2898DeriveBytes(sharedSecret, _salt);

            // Create the streams used for decryption.                
            //byte[] bytes = Convert.FromBase64String(cipherText);
            inputByteArray = HttpServerUtility.UrlTokenDecode(cipherText);

            using (MemoryStream msDecrypt = new MemoryStream(inputByteArray))
            {
                // Create a RijndaelManaged object
                // with the specified key and IV.
                aesAlg = new RijndaelManaged();
                aesAlg.Key = key.GetBytes(aesAlg.KeySize / 8);
                // Get the initialization vector from the encrypted stream
                aesAlg.IV = ReadByteArray(msDecrypt);
                // Create a decrytor to perform the stream transform.
                ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);
                using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                {
                    using (StreamReader srDecrypt = new StreamReader(csDecrypt))

                        // Read the decrypted bytes from the decrypting stream
                        // and place them in a string.
                        plaintext = srDecrypt.ReadToEnd();
                }
            }
        }
        catch (System.Exception ex)
        {
            return "ERROR";
            //throw ex;

        }
        finally
        {
            // Clear the RijndaelManaged object.
            if (aesAlg != null)
                aesAlg.Clear();
        }

        return plaintext;
    }

    static string ConvertStringArrayToString(string[] array)
    {
        //
        // Concatenate all the elements into a StringBuilder.
        //
        StringBuilder builder = new StringBuilder();
        foreach (string value in array)
        {
            builder.Append(value);
            builder.Append('.');
        }
        return builder.ToString();
    }

    private static byte[] ReadByteArray(Stream s)
    {
        byte[] rawLength = new byte[sizeof(int)];
        if (s.Read(rawLength, 0, rawLength.Length) != rawLength.Length)
        {
            throw new SystemException("Stream did not contain properly formatted byte array");
        }

        byte[] buffer = new byte[BitConverter.ToInt32(rawLength, 0)];
        if (s.Read(buffer, 0, buffer.Length) != buffer.Length)
        {
            throw new SystemException("Did not read byte array properly");
        }

        return buffer;
    }

}