C#下的两种加密方式MD5和DEC

md5加密

/// <summary>
    /// MD5加密
    /// </summary>
    /// <param name="toCryString">要加密的字符串</param>
    /// <returns></returns>
    public static string GetMD5Str(string toCryString)
    {
        MD5CryptoServiceProvider hashmd5;
        hashmd5 = new MD5CryptoServiceProvider();
        return BitConverter.ToString(hashmd5.ComputeHash(Encoding.Default.GetBytes(toCryString))).Replace("-", "").ToLower();//asp是小写,把所有字符变小写
    }

DES加密解密

///
/// DEC 加密过程
///
public static string Encrypt(string pToEncrypt, string sKey)
{
DESCryptoServiceProviderdes = new DESCryptoServiceProvider();　//把字符串放到byte数组中

byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);
//byte[]　inputByteArray=Encoding.Unicode.GetBytes(pToEncrypt);

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
MemoryStream ms = new MemoryStream();　　 //使得输入密码必须输入英文文本
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);
}
ret.ToString();
return ret.ToString();
}

///
/// DEC 解密过程
///
public static string Decrypt(string pToDecrypt, string sKey)
{
DESCryptoServiceProviderdes = 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();

StringBuilder ret = new StringBuilder();　//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

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

其中的sKey非常重要,定义的时候定义成string然后赋值等于八个字母或数字,注意,必须8个
这个也很实用,譬如你想进入文章页面,传入的参数的aid=10000
这时把10000给加密
然后接受的时候解密.这样能有效的防止sql注入攻击!