c#的哈希（hash）算法解析

1.方法一:

[c-sharp]
view plaincopyprint?

//适用于C#语言
//使用前需导入以下命名空间：using System.Web.Security;
//第一个参数为需加密的字符串，第二个参数为加密的格式（只有SHA1和MD5两种，可任选一种）
public string EncryptPassword(string PasswordString, string PasswordFormat)
{
string EncryptPassword = null;
if ("SHA1".Equals(PasswordFormat))
{
EncryptPassword = FormsAuthentication.HashPasswordForStoringInConfigFile(PasswordString, "SHA1");
}
else if ("MD5".Equals(PasswordFormat))
{
EncryptPassword = FormsAuthentication.HashPasswordForStoringInConfigFile(PasswordString, "MD5");
}
else
{
EncryptPassword = PasswordString;
}
return EncryptPassword;
}

//======================加密解密方法=====================

using System;
using System.Security.Cryptography;
using System.IO;
using System.Text;/**//// <summary>
/// DEC 加密过程
/// </summary>
/// <param name="pToEncrypt">被加密的字符串</param>
/// <param name="sKey">密钥（只支持8个字节的密钥）</param>
/// <returns>加密后的字符串</returns>
public string Encrypt(string pToEncrypt, string sKey)
...{
//访问数据加密标准(DES)算法的加密服务提供程序 (CSP) 版本的包装对象
DESCryptoServiceProvider des = new DESCryptoServiceProvider();　
des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);　//建立加密对象的密钥和偏移量
des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);　 //原文使用ASCIIEncoding.ASCII方法的GetBytes方法

byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);//把字符串放到byte数组中

MemoryStream ms = new MemoryStream();//创建其支持存储区为内存的流　
//定义将数据流链接到加密转换的流
CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
cs.Write(inputByteArray, 0, inputByteArray.Length);
cs.FlushFinalBlock();
//上面已经完成了把加密后的结果放到内存中去

StringBuilder ret = new StringBuilder();
foreach (byte b in ms.ToArray())
...{
ret.AppendFormat("{0:X2}", b);
}
ret.ToString();
return ret.ToString();
}

/**//**//**//// <summary>
/// DEC 解密过程
/// </summary>
/// <param name="pToDecrypt">被解密的字符串</param>
/// <param name="sKey">密钥（只支持8个字节的密钥，同前面的加密密钥相同）</param>
/// <returns>返回被解密的字符串</returns>

public string Decrypt(string pToDecrypt, string sKey)
...{
DESCryptoServiceProvider des = new DESCryptoServiceProvider();

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

des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);　//建立加密对象的密钥和偏移量，此值重要，不能修改
des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
MemoryStream ms = new MemoryStream();
CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);

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

//建立StringBuild对象，createDecrypt使用的是流对象，必须把解密后的文本变成流对象
StringBuilder ret = new StringBuilder();　

return System.Text.Encoding.Default.GetString(ms.ToArray());
}

//适用于C#语言
//使用前需导入以下命名空间：using System.Web.Security;
//第一个参数为需加密的字符串，第二个参数为加密的格式（只有SHA1和MD5两种，可任选一种）
public string EncryptPassword(string PasswordString, string PasswordFormat)
{
string EncryptPassword = null;
if ("SHA1".Equals(PasswordFormat))
{
EncryptPassword = FormsAuthentication.HashPasswordForStoringInConfigFile(PasswordString, "SHA1");
}
else if ("MD5".Equals(PasswordFormat))
{
EncryptPassword = FormsAuthentication.HashPasswordForStoringInConfigFile(PasswordString, "MD5");
}
else
{
EncryptPassword = PasswordString;
}
return EncryptPassword;
}

//======================加密解密方法=====================

using System;
using System.Security.Cryptography;
using System.IO;
using System.Text;/**//// <summary>
/// DEC 加密过程
/// </summary>
/// <param name="pToEncrypt">被加密的字符串</param>
/// <param name="sKey">密钥（只支持8个字节的密钥）</param>
/// <returns>加密后的字符串</returns>
public string Encrypt(string pToEncrypt, string sKey)
...{
//访问数据加密标准(DES)算法的加密服务提供程序 (CSP) 版本的包装对象
DESCryptoServiceProvider des = new DESCryptoServiceProvider();　
des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);　//建立加密对象的密钥和偏移量
des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);　 //原文使用ASCIIEncoding.ASCII方法的GetBytes方法

byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);//把字符串放到byte数组中

MemoryStream ms = new MemoryStream();//创建其支持存储区为内存的流　
//定义将数据流链接到加密转换的流
CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
cs.Write(inputByteArray, 0, inputByteArray.Length);
cs.FlushFinalBlock();
//上面已经完成了把加密后的结果放到内存中去

StringBuilder ret = new StringBuilder();
foreach (byte b in ms.ToArray())
...{
ret.AppendFormat("{0:X2}", b);
}
ret.ToString();
return ret.ToString();
}

/**//**//**//// <summary>
/// DEC 解密过程
/// </summary>
/// <param name="pToDecrypt">被解密的字符串</param>
/// <param name="sKey">密钥（只支持8个字节的密钥，同前面的加密密钥相同）</param>
/// <returns>返回被解密的字符串</returns>
public string Decrypt(string pToDecrypt, string sKey)
...{
DESCryptoServiceProvider des = new DESCryptoServiceProvider();

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

des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);　//建立加密对象的密钥和偏移量，此值重要，不能修改
des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
MemoryStream ms = new MemoryStream();
CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);

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

//建立StringBuild对象，createDecrypt使用的是流对象，必须把解密后的文本变成流对象
StringBuilder ret = new StringBuilder();　

return System.Text.Encoding.Default.GetString(ms.ToArray());
}

具体在程序中使用加密解密算法的例子如下：

在发送页面

Response.Redirect("~/GridView.aspx?ID=" + Encrypt("zlh","abcdefgh"));

在接受页面

string acceptStr;

acceptStr = Decrypt(Request.QueryString["ID"],"abcdefgh");

转贴来源:http://hi.baidu.com/4092887/blog/item/4dfd89efaf805ee5cf1b3e5a.html

2.方法二:(简单)

FormsAuthentication.HashPasswordForStoringInConfigFile(string, "SHA1");

或

FormsAuthentication.HashPasswordForStoringInConfigFile(String, "MD5");