.Net框架由于擁有CLR提供的豐富庫支持，只需很少的代碼即可實現先前使用C等舊式語言很難實現的加密算法。本類實現一些常用機密算法，供參考。其中MD5算法返回Int的ToString字串。返回數字字母型結果的算法參見之前Blog文章。
using System;
using System.IO;
using System.Data;
using System.Text;
using System.Diagnostics;
using System.Security;
using System.Security.Cryptography;
namespace com.Quickline.Encrypt
{
/// <summary>
/// 類名：HashEncrypt
/// 作用：對傳入的字符串進行Hash運算，返回通過Hash算法加密過的字串。
/// 屬性：［無］
/// 構造函數額參數：
/// IsReturnNum:是否返回為加密后字符的Byte代碼
/// IsCaseSensitive：是否區分大小寫。
/// 方法：此類提供MD5，SHA1，SHA256，SHA512等四種算法，加密字串的長
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">密鑰(最大長度8)</param>
/// <param name="IV">初始化向量(最大長度8)</param>
/// <returns>加密后的字符串</returns>
public string DESEncrypt(string originalValue,string key,string IV)
{
//將key和IV處理成8個字符
key += "12345678";
IV += "12345678";
key = key.Substring(0,8);
IV = IV.Substring(0,8);
SymmetricAlgorithm sa;
ICryptoTransform ct;
MemoryStream ms;
CryptoStream cs;
byte[] byt;
sa = new DESCryptoServiceProvider();
sa.Key = Encoding.UTF8.GetBytes(key);
sa.IV = Encoding.UTF8.GetBytes(IV);
ct = sa.CreateEncryptor();
byt = Encoding.UTF8.GetBytes(originalValue);
ms = new MemoryStream();
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">密鑰(最大長度8)</param>
/// <param name="IV">m初始化向量(最大長度8)</param>
/// <returns>解密后的字符串</returns>
public string DESDecrypt(string encryptedValue,string key,string IV)
{
//將key和IV處理成8個字符
key += "12345678";
IV += "12345678";
key = key.Substring(0,8);
IV = IV.Substring(0,8);
SymmetricAlgorithm sa;
ICryptoTransform ct;
MemoryStream ms;
CryptoStream cs;
byte[] byt;
sa = new DESCryptoServiceProvider();
sa.Key = Encoding.UTF8.GetBytes(key);
sa.IV = Encoding.UTF8.GetBytes(IV);
ct = sa.CreateDecryptor();
byt = Convert.FromBase64String(encryptedValue);
ms = new MemoryStream();
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 = "";
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;
}
}
} | 
