public string GetMD5Str(string input)
{
// Use input string to calculate MD5 hash
MD5 md5 = System.Security.Cryptography.MD5.Create();
byte[] inputBytes = System.Text.Encoding.ASCII.GetBytes(input);
byte[] hashBytes = md5.ComputeHash(inputBytes);

// Convert the byte array to hexadecimal string
StringBuilder sb = new StringBuilder();
for (int i = 0; i < hashBytes.Length; i++)
{
sb.Append(hashBytes[i].ToString("X2"));
// To force the hex string to lower-case letters instead of
// upper-case, use he following line instead:
// sb.Append(hashBytes[i].ToString("x2"));
}
return sb.ToString().ToLower();
}

MD5方法代码（生成小写的md5） C#版本