DES加密，解密

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

namespace Elight.Infrastructure
{
/// <summary>
/// 字符串加密解密方法扩展类。
/// </summary>
public static class Encrypt
{
#region DES加密解密

/// <summary>
/// 默认密钥。
/// </summary>
private const string DESENCRYPT_KEY = "hsdjxlzf";

/// <summary>
/// DES加密，使用自定义密钥。
/// </summary>
/// <param name="text">待加密的明文</param>
/// <param name="key">8位字符的密钥字符串</param>
/// <returns></returns>
public static string DESEncrypt(this string text, string key)
{
if (key.Length != 8)
{
key = DESENCRYPT_KEY;
}
DESCryptoServiceProvider des = new DESCryptoServiceProvider();
byte[] inputByteArray = Encoding.GetEncoding("UTF-8").GetBytes(text);

byte[] a = ASCIIEncoding.ASCII.GetBytes(key);
des.Key = ASCIIEncoding.ASCII.GetBytes(key);
des.IV = ASCIIEncoding.ASCII.GetBytes(key);
MemoryStream ms = new MemoryStream();
CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);

cs.Write(inputByteArray, 0, inputByteArray.Length);
cs.FlushFinalBlock();

StringBuilder ret = new StringBuilder();
foreach (byte b in ms.ToArray())
{
ret.AppendFormat("{0:X2}", b);//将第一个参数转换为十六进制数,长度为2,不足前面补0
}
return ret.ToString();
}

/// <summary>
/// DES解密，使用自定义密钥。
/// </summary>
/// <param name="cyphertext">待解密的秘文</param>
/// <param name="key">必须是8位字符的密钥字符串(不能有特殊字符)</param>
/// <returns></returns>
public static string DESDecrypt(this string cyphertext, string key)
{
if (key.Length != 8)
{
key = DESENCRYPT_KEY;
}
if (string.IsNullOrEmpty(cyphertext))
return string.Empty;
DESCryptoServiceProvider des = new DESCryptoServiceProvider();

byte[] inputByteArray = new byte[cyphertext.Length / 2];
for (int x = 0; x < cyphertext.Length / 2; x++)
{
int i = (Convert.ToInt32(cyphertext.Substring(x * 2, 2), 16));
inputByteArray[x] = (byte)i;
}

des.Key = ASCIIEncoding.ASCII.GetBytes(key);
des.IV = ASCIIEncoding.ASCII.GetBytes(key);
MemoryStream ms = new MemoryStream();
CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
cs.Write(inputByteArray, 0, inputByteArray.Length);
cs.FlushFinalBlock();

StringBuilder ret = new StringBuilder();

return System.Text.Encoding.GetEncoding("UTF-8").GetString(ms.ToArray());
}

/// <summary>
/// DES加密，使用默认密钥。
/// </summary>
/// <param name="text">待加密的明文</param>
/// <returns></returns>
public static string DESEncrypt(this string text)
{
return DESEncrypt(text, DESENCRYPT_KEY);
}

/// <summary>
/// DES解密，使用默认密钥。
/// </summary>
/// <param name="cyphertext">待解密的秘文</param>
/// <returns></returns>
public static string DESDecrypt(this string cyphertext)
{
return DESDecrypt(cyphertext, DESENCRYPT_KEY);
}
#endregion

#region Base64加密解密
/// <summary>
/// Base64加密，采用指定字符编码方式加密。
/// </summary>
/// <param name="input">待加密的明文</param>
/// <param name="encode">字符编码</param>
/// <returns></returns>
public static string Base64Encrypt(this string input, Encoding encode)
{
return Convert.ToBase64String(encode.GetBytes(input));
}

/// <summary>
/// Base64加密，采用UTF8编码方式加密。
/// </summary>
/// <param name="input">待加密的明文</param>
/// <returns></returns>
public static string Base64Encrypt(this string input)
{
return Base64Encrypt(input, new UTF8Encoding());
}

/// <summary>
/// Base64解密，采用UTF8编码方式解密。
/// </summary>
/// <param name="input">待解密的秘文</param>
/// <returns></returns>
public static string Base64Decrypt(this string input)
{
return Base64Decrypt(input, new UTF8Encoding());
}

/// <summary>
/// Base64解密，采用指定字符编码方式解密。
/// </summary>
/// <param name="input">待解密的秘文</param>
/// <param name="encode">字符的编码</param>
/// <returns></returns>
public static string Base64Decrypt(this string input, Encoding encode)
{
return encode.GetString(Convert.FromBase64String(input));
}
#endregion

#region MD5加密
/// <summary>
/// 字符串MD5加密。
/// </summary>
/// <param name="strOri">需要加密的字符串</param>
/// <returns></returns>
public static string MD5Encrypt(this string text)
{
// Create a new instance of the MD5CryptoServiceProvider object.
System.Security.Cryptography.MD5 md5Hasher = System.Security.Cryptography.MD5.Create();
// Convert the input string to a byte array and compute the hash.
byte[] data = md5Hasher.ComputeHash(Encoding.Default.GetBytes(text));
// Create a new Stringbuilder to collect the bytes
// and create a string.
StringBuilder sBuilder = new StringBuilder();
// Loop through each byte of the hashed data
// and format each one as a hexadecimal string.
for (int i = 0; i < data.Length; i++)
{
sBuilder.Append(data[i].ToString("x2"));
}
// Return the hexadecimal string.
return sBuilder.ToString();
}

/// <summary>
/// 文件流MD5加密。
/// </summary>
/// <param name="stream">需要加密的文件流</param>
/// <returns></returns>
public static string MD5Encrypt(this Stream stream)
{
MD5 md5serv = MD5CryptoServiceProvider.Create();
byte[] buffer = md5serv.ComputeHash(stream);
StringBuilder sb = new StringBuilder();
foreach (byte var in buffer)
{
sb.Append(var.ToString("x2"));
}
return sb.ToString();
}
#endregion
}
}