RC2 字符串加密，支持15位密码加密，可设置密匙

public static string Encrypt(string EncryptString, string EncryptKey)
{

if (string.IsNullOrEmpty(EncryptString)) { throw (new Exception("密文不得为空")); }

if (string.IsNullOrEmpty(EncryptKey)) { throw (new Exception("密钥不得为空")); }

if (EncryptKey.Length < 5 || EncryptKey.Length > 36) { throw (new Exception("密钥必须为5-16位")); }

string m_strEncrypt = "";

byte[] m_btIV = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };

RC2CryptoServiceProvider m_RC2Provider = new RC2CryptoServiceProvider();

try
{

byte[] m_btEncryptString = Encoding.Default.GetBytes(EncryptString);

MemoryStream m_stream = new MemoryStream();

CryptoStream m_cstream = new CryptoStream(m_stream, m_RC2Provider.CreateEncryptor(Encoding.Default.GetBytes(EncryptKey), m_btIV), CryptoStreamMode.Write);

m_cstream.Write(m_btEncryptString, 0, m_btEncryptString.Length);

m_cstream.FlushFinalBlock();

m_strEncrypt = Convert.ToBase64String(m_stream.ToArray());

m_stream.Close(); m_stream.Dispose();

m_cstream.Close(); m_cstream.Dispose();

}

catch (IOException ex) { throw ex; }

catch (CryptographicException ex) { throw ex; }

catch (ArgumentException ex) { throw ex; }

catch (Exception ex) { throw ex; }

finally { m_RC2Provider.Clear(); }

return m_strEncrypt;

}

/// <summary>

/// RC2 解密(用变长密钥对大量数据进行加密)

/// </summary>

/// <paramname="DecryptString">待解密密文</param>

/// <paramname="DecryptKey">解密密钥</param>

///<returns>returns</returns>

public static string Decrypt(string DecryptString, string DecryptKey)
{

if (string.IsNullOrEmpty(DecryptString)) { throw (new Exception("密文不得为空")); }

if (string.IsNullOrEmpty(DecryptKey)) { throw (new Exception("密钥不得为空")); }

if (DecryptKey.Length < 5 || DecryptKey.Length > 16) { throw (new Exception("密钥必须为5-16位")); }

byte[] m_btIV = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };

string m_strDecrypt = "";

RC2CryptoServiceProvider m_RC2Provider = new RC2CryptoServiceProvider();

try
{

byte[] m_btDecryptString = Convert.FromBase64String(DecryptString);

MemoryStream m_stream = new MemoryStream();

CryptoStream m_cstream = new CryptoStream(m_stream, m_RC2Provider.CreateDecryptor(Encoding.Default.GetBytes(DecryptKey), m_btIV), CryptoStreamMode.Write);

m_cstream.Write(m_btDecryptString, 0, m_btDecryptString.Length);

m_cstream.FlushFinalBlock();

m_strDecrypt = Encoding.Default.GetString(m_stream.ToArray());

m_stream.Close(); m_stream.Dispose();

m_cstream.Close(); m_cstream.Dispose();

}

catch (IOException ex) { throw ex; }

catch (CryptographicException ex) { throw ex; }

catch (ArgumentException ex) { throw ex; }

catch (Exception ex) { throw ex; }

finally { m_RC2Provider.Clear(); }

return m_strDecrypt;

}