转http://www.cnblogs.com/hongcing/archive/2010/02/03/1662608.html
//如果是文本，先转换为字节序列，如果有汉字，请不要使用 ASCII 编码，会导致汉字变成问号
byte[] buffer = Encoding.UTF8.GetBytes("洪星的博客");//UTF-8 编码
buffer = Encoding.Default.GetBytes("洪星的博客");//GBK/GB2312 编码
//16字节,128位
MD5CryptoServiceProvider MD5 = new MD5CryptoServiceProvider();
byte[] h1 = MD5.ComputeHash(buffer);
//20字节,160位
SHA1CryptoServiceProvider SHA1 = new SHA1CryptoServiceProvider();
byte[] h2 = SHA1.ComputeHash(buffer);
//32字节,256位
SHA256CryptoServiceProvider SHA256 = new SHA256CryptoServiceProvider();
byte[] h3 = SHA256.ComputeHash(buffer);
//48字节,384位
SHA384CryptoServiceProvider SHA384 = new SHA384CryptoServiceProvider();
byte[] h4 = SHA384.ComputeHash(buffer);
//64字节,512位
SHA512CryptoServiceProvider SHA512 = new SHA512CryptoServiceProvider();
byte[] h5 = SHA512.ComputeHash(buffer);
string s1 = BitConverter.ToString(h1).Replace("-", string.Empty);
string s2 = BitConverter.ToString(h2).Replace("-", string.Empty);
string s3 = BitConverter.ToString(h3).Replace("-", string.Empty);
string s4 = BitConverter.ToString(h4).Replace("-", string.Empty);
string s5 = BitConverter.ToString(h5).Replace("-", string.Empty);
Console.WriteLine(s1);
Console.WriteLine(s2);
Console.WriteLine(s3);
Console.WriteLine(s4);
Console.WriteLine(s5);