txt 要加密的字符；output加密后的字符
public string HashMD5(string txt)
{
byte[] result = ((HashAlgorithm)System.Security.Cryptography.CryptoConfig.CreateFromName("MD5")).ComputeHash(System.Text.Encoding.UTF8.GetBytes(txt));
StringBuilder output = new StringBuilder(16);
for (int i = 0; i < result.Length;i++)
{
output.Append(result[i].ToString("x2",System.Globalization.CultureInfo.InvariantCulture));
}
return output.ToString();
}