完整加密类（提供MD5，SHA1，SHA256，SHA512，DES加密和解密）

/// <summary>
/// 类名：HashEncrypt
/// 作用：对传入的字符串进行Hash运算，返回通过Hash算法加密过的字串。
/// 属性：［无］
/// 构造函数额参数：
/// IsReturnNum:是否返回为加密后字符的Byte代码
/// IsCaseSensitive：是否区分大小写。
/// 方法：此类提供MD5，SHA1，SHA256，SHA512等四种算法，加密字串的长度依次增大。
/// </summary>
public class HashEncrypt
{
//private string strIN;
private bool isReturnNum;
private bool isCaseSensitive;

public HashEncrypt(bool IsCaseSensitive, bool IsReturnNum)
{
this.isReturnNum = IsReturnNum;
this.isCaseSensitive = IsCaseSensitive;
}

private string GetStrIN(string strIN)
{
//string strIN = strIN;
if (strIN.Length == 0)
{
strIN = "~NULL~";
}
if (isCaseSensitive == false)
{
strIN = strIN.ToUpper();
}
return strIN;
}
public string MD5Encrypt(string strIN)
{
//string strIN = getstrIN(strIN);
byte[] tmpByte;
MD5 md5 = new MD5CryptoServiceProvider();
tmpByte = md5.ComputeHash(GetKeyByteArray(GetStrIN(strIN)));
md5.Clear();
return GetStringValue(tmpByte);
}

public string SHA1Encrypt(string strIN)
{
//string strIN = getstrIN(strIN);
byte[] tmpByte;
SHA1 sha1 = new SHA1CryptoServiceProvider();
tmpByte = sha1.ComputeHash(GetKeyByteArray(strIN));
sha1.Clear();
return GetStringValue(tmpByte);

}

public string SHA256Encrypt(string strIN)
{
//string strIN = getstrIN(strIN);
byte[] tmpByte;
SHA256 sha256 = new SHA256Managed();

tmpByte = sha256.ComputeHash(GetKeyByteArray(strIN));
sha256.Clear();
return GetStringValue(tmpByte);

}

public string SHA512Encrypt(string strIN)
{
//string strIN = getstrIN(strIN);
byte[] tmpByte;
SHA512 sha512 = new SHA512Managed();

tmpByte = sha512.ComputeHash(GetKeyByteArray(strIN));
sha512.Clear();

return GetStringValue(tmpByte);

}

/// <summary>
/// 使用DES加密（Added by niehl 2005-4-6）
/// </summary>
/// <param name="originalValue">待加密的字符串</param>
/// <param name="key">密钥(最大长度8)</param>
/// <param name="IV">初始化向量(最大长度8)</param>
/// <returns>加密后的字符串</returns>
public string DESEncrypt(string originalValue, string key, string IV)
{
//将key和IV处理成8个字符
key += "12345678";
IV += "12345678";
key = key.Substring(0, 8);
IV = IV.Substring(0, 8);

SymmetricAlgorithm sa = new DESCryptoServiceProvider();
sa.Key = Encoding.UTF8.GetBytes(key);
sa.IV = Encoding.UTF8.GetBytes(IV);
ICryptoTransform ct = sa.CreateEncryptor();
byte[] byt = Encoding.UTF8.GetBytes(originalValue);
MemoryStream ms = new MemoryStream();
CryptoStream cs = new CryptoStream(ms, ct,
CryptoStreamMode.Write);
cs.Write(byt, 0, byt.Length);
cs.FlushFinalBlock();

cs.Close();

return Convert.ToBase64String(ms.ToArray());

}

public string DESEncrypt(string originalValue, string key)
{
return DESEncrypt(originalValue, key, key);
}

/// <summary>
/// 使用DES解密（Added by niehl 2005-4-6）
/// </summary>
/// <param name="encryptedValue">待解密的字符串</param>
/// <param name="key">密钥(最大长度8)</param>
/// <param name="IV">m初始化向量(最大长度8)</param>
/// <returns>解密后的字符串</returns>
public string DESDecrypt(string encryptedValue, string key, string IV)
{
//将key和IV处理成8个字符
key += "12345678";
IV += "12345678";
key = key.Substring(0, 8);
IV = IV.Substring(0, 8);

SymmetricAlgorithm sa = new DESCryptoServiceProvider();
sa.Key = Encoding.UTF8.GetBytes(key);
sa.IV = Encoding.UTF8.GetBytes(IV);
ICryptoTransform ct = sa.CreateDecryptor();

byte[] byt = Convert.FromBase64String(encryptedValue);
MemoryStream ms = new MemoryStream();
CryptoStream cs = new CryptoStream(ms, ct, CryptoStreamMode.Write);
cs.Write(byt, 0, byt.Length);
cs.FlushFinalBlock();
cs.Close();
return Encoding.UTF8.GetString(ms.ToArray());

}

public string DESDecrypt(string encryptedValue, string key)
{
return DESDecrypt(encryptedValue, key, key);
}

private string GetStringValue(byte[] Byte)
{
string tmpString = string.Empty;
if (this.isReturnNum == false)
{
ASCIIEncoding Asc = new ASCIIEncoding();
tmpString = Asc.GetString(Byte);
}
else
{
int iCounter;
for (iCounter = 0; iCounter < Byte.Length; iCounter++)
{
tmpString = tmpString + Byte[iCounter].ToString();
}
}
return tmpString;
}

private byte[] GetKeyByteArray(string strKey)
{

ASCIIEncoding Asc = new ASCIIEncoding();
int tmpStrLen = strKey.Length;
byte[] tmpByte = new byte[tmpStrLen - 1];
tmpByte = Asc.GetBytes(strKey);
return tmpByte;

}

}