MD5

/// <summary>
/// 不可逆加密
/// 1 防止被篡改
/// 2 防止明文存储
/// 3 防止抵赖，数字签名
/// </summary>
using System.Security.Cryptography;
public class MD5Encrypt
{
#region MD5
/// <summary>
/// MD5加密,和动网上的16/32位MD5加密结果相同,
/// 使用的UTF8编码
/// </summary>
/// <param name="strSource">待加密字串</param>
/// <param name="length">16或32值之一,其它则采用.net默认MD5加密算法</param>
/// <returns>加密后的字串</returns>
public static string Encrypt(string source, int length = 32)//默认参数
{
HashAlgorithm provider = CryptoConfig.CreateFromName("MD5") as HashAlgorithm;
if (string.IsNullOrEmpty(source)) return string.Empty;

byte[] bytes = Encoding.UTF8.GetBytes(source);// Encoding.ASCII.GetBytes(source);
byte[] hashValue = provider.ComputeHash(bytes);
StringBuilder sb = new StringBuilder();
switch (length)
{
case 16://16位密文是32位密文的9到24位字符
for (int i = 4; i < 12; i++)
sb.Append(hashValue[i].ToString("x2"));
break;
case 32:
for (int i = 0; i < 16; i++)
{
sb.Append(hashValue[i].ToString("x2"));
}
break;
default:
for (int i = 0; i < hashValue.Length; i++)
{
sb.Append(hashValue[i].ToString("x2"));
}
break;
}
return sb.ToString();
}
#endregion MD5
}

MD5Encrypt.Encrypt("张三李四")