MD5 (Files & Processes)

public static string GetMD5HashFromFile(string fileName)
{
FileStream file = new FileInfo(fileName).OpenRead();
MD5 md5 = new MD5CryptoServiceProvider();
byte[] retVal = md5.ComputeHash(file);
file.Close();

ASCIIEncoding enc = new ASCIIEncoding();
return enc.GetString(retVal);
}

public static string getFilesMD5Hash(string filepath)
{
//MD5 hash provider for computing the hash of the file
MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();

//open the file
FileStream stream = new FileStream(filepath, FileMode.Open, FileAccess.Read, FileShare.Read, 8192);

//calculate the files hash
md5.ComputeHash(stream);

//close our stream
stream.Close();

//byte array of files hash
byte[] hash = md5.Hash;

//string builder to hold the results
StringBuilder sb = new StringBuilder();

//loop through each byte in the byte array
foreach (byte b in hash)
{
//format each byte into the proper value and append
//current value to return value
sb.Append(string.Format("{0:X2}", b));
}

//return the MD5 hash of the file
return sb.ToString();
}

Code:

// SHA1 hash:
string h1 = Convert.ToBase64String(new System.Security.Cryptography.SHA1CryptoServiceProvider().ComputeHash(Encoding.ASCII.GetBytes("one two")));

// MD5 hash:
string h2 = Convert.ToBase64String(new System.Security.Cryptography.MD5CryptoServiceProvider().ComputeHash(Encoding.ASCII.GetBytes("one two")))