C#.net实现密码加密算法

//SHA-1算法
string password =
System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(Password.Text,
"SHA1");
//MD5算法
string password1 =
System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(Password.Text,
"MD5");

加密后生成不可逆密文保存到数据库中。用户登录时用加密计算后的密文与数据库中的密码密文比较。一致则通过验证，不一致则返回登录错误。
这种加密算法是不可逆的，所以除了用户自己，其他人无法得知用户的真实密码内容。

SHA-1算法和MD5算法的区别：
SHA-1比MD5多32位密文，所以更安全。由于同样的原因，MD5比SHA-1的运算速度更快。

加密算法总汇
方法一：
   
//须添加对System.Web的引用
    using System.Web.Security;
    
    ...

/// <summary>
    /// SHA1加密字符串
    ///
</summary>
    /// <param name="source">源字符串</param>

/// <returns>加密后的字符串</returns>
    public string
SHA1(string source)
    {
        return
FormsAuthentication.HashPasswordForStoringInConfigFile(source, "SHA1");
   
}

/// <summary>
    /// MD5加密字符串
    ///
</summary>
    /// <param name="source">源字符串</param>

/// <returns>加密后的字符串</returns>
    public string
MD5(string source)
    {
        return
FormsAuthentication.HashPasswordForStoringInConfigFile(source, "MD5");;
   
}

方法二(可逆加密解密)：
    using System.Security.Cryptography;

...
    
    public string Encode(string data)
    {

byte[] byKey = System.Text.ASCIIEncoding.ASCII.GetBytes(KEY_64);

byte[] byIV = System.Text.ASCIIEncoding.ASCII.GetBytes(IV_64);

DESCryptoServiceProvider cryptoProvider = new
DESCryptoServiceProvider();
        int i = cryptoProvider.KeySize;

MemoryStream ms = new MemoryStream();
        CryptoStream cst =
new CryptoStream(ms, cryptoProvider.CreateEncryptor(byKey, byIV),
CryptoStreamMode.Write);
    
        StreamWriter sw = new
StreamWriter(cst);
        sw.Write(data);
        sw.Flush();

cst.FlushFinalBlock();
        sw.Flush();
        return
Convert.ToBase64String(ms.GetBuffer(), 0, (int)ms.Length);
    
    }

public string Decode(string data)
    {
        byte[]
byKey = System.Text.ASCIIEncoding.ASCII.GetBytes(KEY_64);
        byte[]
byIV = System.Text.ASCIIEncoding.ASCII.GetBytes(IV_64);
    
       
byte[] byEnc;
        try
        {
            byEnc =
Convert.FromBase64String(data);
        }
        catch
        {

return null;
        }
    
       
DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider();

MemoryStream ms = new MemoryStream(byEnc);
        CryptoStream
cst = new CryptoStream(ms, cryptoProvider.CreateDecryptor(byKey, byIV),
CryptoStreamMode.Read);
        StreamReader sr = new StreamReader(cst);

return sr.ReadToEnd();
    }

方法三(MD5不可逆)：
    using
System.Security.Cryptography;
    
    ...
    
    //MD5不可逆加密

//32位加密
    
    public string GetMD5_32(string s,
string _input_charset)
    {
        MD5 md5 = new
MD5CryptoServiceProvider();
        byte[] t =
md5.ComputeHash(Encoding.GetEncoding(_input_charset).GetBytes(s));
       
StringBuilder sb = new StringBuilder(32);
        for (int i = 0; i <
t.Length; i++)
        {
           
sb.Append(t[i].ToString("x").PadLeft(2, '0'));
        }
        return
sb.ToString();
    }
    
    //16位加密
    public static string
GetMd5_16(string ConvertString)
    {
        MD5CryptoServiceProvider
md5 = new MD5CryptoServiceProvider();
        string t2 =
BitConverter.ToString(md5.ComputeHash(UTF8Encoding.Default.GetBytes(ConvertString)),
4, 8);
        t2 = t2.Replace("-", "");
        return t2;
   
}

方法四(对称加密)：
    using System.IO;
    using
System.Security.Cryptography;
    
    ...
    
    private
SymmetricAlgorithm mobjCryptoService;
    private string Key;
    ///
<summary>   
    /// 对称加密类的构造函数   
    /// </summary>

public SymmetricMethod()
    {
        mobjCryptoService = new
RijndaelManaged();
        Key =
"Guz(%&hj7x89H$yuBI0456FtmaT5&fvHUFCy76*h%(HilJ$lhj!y6&(*jkP87jH7";

}
    /// <summary>   
    /// 获得密钥   
    ///
</summary>   
    /// <returns>密钥</returns>   
   
private byte[] GetLegalKey()
    {
        string sTemp = Key;

mobjCryptoService.GenerateKey();
        byte[] bytTemp =
mobjCryptoService.Key;
        int KeyLength = bytTemp.Length;
       
if (sTemp.Length > KeyLength)
            sTemp = sTemp.Substring(0,
KeyLength);
        else if (sTemp.Length < KeyLength)
           
sTemp = sTemp.PadRight(KeyLength, ' ');
        return
ASCIIEncoding.ASCII.GetBytes(sTemp);
    }
    /// <summary>

/// 获得初始向量IV   
    /// </summary>   
    ///
<returns>初试向量IV</returns>   
    private byte[] GetLegalIV()

{
        string sTemp =
"E4ghj*Ghg7!rNIfb&95GUY86GfghUb#er57HBh(u%g6HJ($jhWk7&!hg4ui%$hjk";

mobjCryptoService.GenerateIV();
        byte[] bytTemp =
mobjCryptoService.IV;
        int IVLength = bytTemp.Length;
        if
(sTemp.Length > IVLength)
            sTemp = sTemp.Substring(0,
IVLength);
        else if (sTemp.Length < IVLength)
           
sTemp = sTemp.PadRight(IVLength, ' ');
        return
ASCIIEncoding.ASCII.GetBytes(sTemp);
    }
    /// <summary>

/// 加密方法   
    /// </summary>   
    /// <param
name="Source">待加密的串</param>   
    ///
<returns>经过加密的串</returns>   
    public string Encrypto(string
Source)
    {
        byte[] bytIn = UTF8Encoding.UTF8.GetBytes(Source);

MemoryStream ms = new MemoryStream();
       
mobjCryptoService.Key = GetLegalKey();
        mobjCryptoService.IV =
GetLegalIV();
        ICryptoTransform encrypto =
mobjCryptoService.CreateEncryptor();
        CryptoStream cs = new
CryptoStream(ms, encrypto, CryptoStreamMode.Write);
        cs.Write(bytIn,
0, bytIn.Length);
        cs.FlushFinalBlock();
        ms.Close();

byte[] bytOut = ms.ToArray();
        return
Convert.ToBase64String(bytOut);
    }
    /// <summary>   
   
/// 解密方法   
    /// </summary>   
    /// <param
name="Source">待解密的串</param>   
    ///
<returns>经过解密的串</returns>   
    public string Decrypto(string
Source)
    {
        byte[] bytIn = Convert.FromBase64String(Source);

MemoryStream ms = new MemoryStream(bytIn, 0, bytIn.Length);

mobjCryptoService.Key = GetLegalKey();
       
mobjCryptoService.IV = GetLegalIV();
        ICryptoTransform encrypto =
mobjCryptoService.CreateDecryptor();
        CryptoStream cs = new
CryptoStream(ms, encrypto, CryptoStreamMode.Read);
        StreamReader sr =
new StreamReader(cs);
        return sr.ReadToEnd();
   
}

方法五：
    using System.IO;
    using
System.Security.Cryptography;
    using System.Text;
    
    ...

//默认密钥向量
    private static byte[] Keys = { 0x12, 0x34,
0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };
    /// <summary>
    ///
DES加密字符串
    /// </summary>
    /// <param
name="encryptString">待加密的字符串</param>
    /// <param
name="encryptKey">加密密钥,要求为8位</param>
    ///
<returns>加密成功返回加密后的字符串，失败返回源串</returns>
    public static string
EncryptDES(string encryptString, string encryptKey)
    {
       
try
        {
            byte[] rgbKey =
Encoding.UTF8.GetBytes(encryptKey.Substring(0, 8));
            byte[] rgbIV
= Keys;
            byte[] inputByteArray =
Encoding.UTF8.GetBytes(encryptString);
            DESCryptoServiceProvider
dCSP = new DESCryptoServiceProvider();
            MemoryStream mStream =
new MemoryStream();
            CryptoStream cStream = new
CryptoStream(mStream, dCSP.CreateEncryptor(rgbKey, rgbIV),
CryptoStreamMode.Write);
            cStream.Write(inputByteArray, 0,
inputByteArray.Length);
            cStream.FlushFinalBlock();

return Convert.ToBase64String(mStream.ToArray());
        }

catch
        {
            return encryptString;
       
}
    }
    
    /// <summary>
    /// DES解密字符串
   
/// </summary>
    /// <param
name="decryptString">待解密的字符串</param>
    /// <param
name="decryptKey">解密密钥,要求为8位,和加密密钥相同</param>
    ///
<returns>解密成功返回解密后的字符串，失败返源串</returns>
    public static string
DecryptDES(string decryptString, string decryptKey)
    {
       
try
        {
            byte[] rgbKey =
Encoding.UTF8.GetBytes(decryptKey);
            byte[] rgbIV = Keys;

byte[] inputByteArray = Convert.FromBase64String(decryptString);

DESCryptoServiceProvider DCSP = new DESCryptoServiceProvider();

MemoryStream mStream = new MemoryStream();
           
CryptoStream cStream = new CryptoStream(mStream, DCSP.CreateDecryptor(rgbKey,
rgbIV), CryptoStreamMode.Write);
            cStream.Write(inputByteArray,
0, inputByteArray.Length);
            cStream.FlushFinalBlock();

return Encoding.UTF8.GetString(mStream.ToArray());
        }

catch
        {
            return decryptString;
       
}
    }

方法六(文件加密)：
    using System.IO;
    using
System.Security.Cryptography;
    using System.Text;
    
    ...

//加密文件
    private static void EncryptData(String inName,
String outName, byte[] desKey, byte[] desIV)
    {
        //Create the
file streams to handle the input and output files.
        FileStream fin =
new FileStream(inName, FileMode.Open, FileAccess.Read);
        FileStream
fout = new FileStream(outName, FileMode.OpenOrCreate, FileAccess.Write);

fout.SetLength(0);
    
        //Create variables to help
with read and write.
        byte[] bin = new byte[100]; //This is
intermediate storage for the encryption.
        long rdlen =
0;              //This is the total number of bytes written.
        long
totlen = fin.Length;    //This is the total length of the input file.

int len;                     //This is the number of bytes to be
written at a time.
    
        DES des = new
DESCryptoServiceProvider();
        CryptoStream encStream = new
CryptoStream(fout, des.CreateEncryptor(desKey, desIV), CryptoStreamMode.Write);

//Read from the input file, then encrypt and write to the
output file.
        while (rdlen < totlen)
        {
           
len = fin.Read(bin, 0, 100);
            encStream.Write(bin, 0, len);

rdlen = rdlen + len;
        }
    
       
encStream.Close();
        fout.Close();
        fin.Close();
    }

//解密文件
    private static void DecryptData(String inName,
String outName, byte[] desKey, byte[] desIV)
    {
        //Create the
file streams to handle the input and output files.
        FileStream fin =
new FileStream(inName, FileMode.Open, FileAccess.Read);
        FileStream
fout = new FileStream(outName, FileMode.OpenOrCreate, FileAccess.Write);

fout.SetLength(0);
    
        //Create variables to help
with read and write.
        byte[] bin = new byte[100]; //This is
intermediate storage for the encryption.
        long rdlen =
0;              //This is the total number of bytes written.
        long
totlen = fin.Length;    //This is the total length of the input file.

int len;                     //This is the number of bytes to be
written at a time.
    
        DES des = new
DESCryptoServiceProvider();
        CryptoStream encStream = new
CryptoStream(fout, des.CreateDecryptor(desKey, desIV), CryptoStreamMode.Write);

//Read from the input file, then encrypt and write to the
output file.
        while (rdlen < totlen)
        {
           
len = fin.Read(bin, 0, 100);
            encStream.Write(bin, 0, len);

rdlen = rdlen + len;
        }
    
       
encStream.Close();
        fout.Close();
        fin.Close();

}

using System;
using
System.Security.Cryptography;//这个是处理文字编码的前提
using System.Text;
using
System.IO;
/// <summary>
/// DES加密方法
/// </summary>
///
<param name="strPlain">明文</param>
/// <param
name="strDESKey">密钥</param>
/// <param
name="strDESIV">向量</param>
///
<returns>密文</returns>
public string DESEncrypt(string
strPlain,string strDESKey,string strDESIV)
{
//把密钥转换成字节数组
byte[]
bytesDESKey=ASCIIEncoding.ASCII.GetBytes(strDESKey);
//把向量转换成字节数组
byte[]
bytesDESIV=ASCIIEncoding.ASCII.GetBytes(strDESIV);
//声明1个新的DES对象
DESCryptoServiceProvider
desEncrypt=new DESCryptoServiceProvider();
//开辟一块内存流
MemoryStream
msEncrypt=new MemoryStream();
//把内存流对象包装成加密流对象
CryptoStream
csEncrypt=new
CryptoStream(msEncrypt,desEncrypt.CreateEncryptor(bytesDESKey,bytesDESIV),CryptoStreamMode.Write);
//把加密流对象包装成写入流对象
StreamWriter
swEncrypt=new
StreamWriter(csEncrypt);
//写入流对象写入明文
swEncrypt.WriteLine(strPlain);
//写入流关闭
swEncrypt.Close();
//加密流关闭
csEncrypt.Close();
//把内存流转换成字节数组，内存流现在已经是密文了
byte[]
bytesCipher=msEncrypt.ToArray();
//内存流关闭
msEncrypt.Close();
//把密文字节数组转换为字符串，并返回
return
UnicodeEncoding.Unicode.GetString(bytesCipher);
}

///
<summary>
/// DES解密方法
/// </summary>
/// <param
name="strCipher">密文</param>
/// <param
name="strDESKey">密钥</param>
/// <param
name="strDESIV">向量</param>
///
<returns>明文</returns>
public string DESDecrypt(string
strCipher,string strDESKey,string strDESIV)
{
//把密钥转换成字节数组
byte[]
bytesDESKey=ASCIIEncoding.ASCII.GetBytes(strDESKey);
//把向量转换成字节数组
byte[]
bytesDESIV=ASCIIEncoding.ASCII.GetBytes(strDESIV);
//把密文转换成字节数组
byte[]
bytesCipher=UnicodeEncoding.Unicode.GetBytes(strCipher);
//声明1个新的DES对象
DESCryptoServiceProvider
desDecrypt=new
DESCryptoServiceProvider();
//开辟一块内存流，并存放密文字节数组
MemoryStream
msDecrypt=new MemoryStream(bytesCipher);
//把内存流对象包装成解密流对象
CryptoStream
csDecrypt=new
CryptoStream(msDecrypt,desDecrypt.CreateDecryptor(bytesDESKey,bytesDESIV),CryptoStreamMode.Read);
//把解密流对象包装成读出流对象
StreamReader
srDecrypt=new StreamReader(csDecrypt);
//明文=读出流的读出内容
string
strPlainText=srDecrypt.ReadLine();
//读出流关闭
srDecrypt.Close();
//解密流关闭
csDecrypt.Close();
//内存流关闭
msDecrypt.Close();
//返回明文
return
strPlainText;
}