HashAlgorithm.ComputeHash Method (Byte[])

 

Computes the hash value for the specified byte array.

Namespace:   System.Security.Cryptography
Assembly:  mscorlib (in mscorlib.dll)

public byte[] ComputeHash(
	byte[] buffer
)

Parameters

buffer
Type: System.Byte[]

The input to compute the hash code for.

Return Value

Type: System.Byte[]

The computed hash code.

Exception Condition
ArgumentNullException

buffer is null.

ObjectDisposedException

The object has already been disposed.

The following example computes the MD5 hash value of a string and returns the hash as a 32-character, hexadecimal-formatted string. The hash string created by this code example is compatible with any MD5 hash function (on any platform) that creates a 32-character, hexadecimal-formatted hash string.

using System;
using System.Security.Cryptography;
using System.Text;

namespace MD5Sample
{
    class Program
    {
        static void Main(string[] args)
        {
            string source = "Hello World!";
            using (MD5 md5Hash = MD5.Create())
            {
                string hash = GetMd5Hash(md5Hash, source);

                Console.WriteLine("The MD5 hash of " + source + " is: " + hash + ".");

                Console.WriteLine("Verifying the hash...");

                if (VerifyMd5Hash(md5Hash, source, hash))
                {
                    Console.WriteLine("The hashes are the same.");
                }
                else
                {
                    Console.WriteLine("The hashes are not same.");
                }
            }



        }
        static string GetMd5Hash(MD5 md5Hash, string input)
        {

            // Convert the input string to a byte array and compute the hash.
            byte[] data = md5Hash.ComputeHash(Encoding.UTF8.GetBytes(input));

            // Create a new Stringbuilder to collect the bytes
            // and create a string.
            StringBuilder sBuilder = new StringBuilder();

            // Loop through each byte of the hashed data 
            // and format each one as a hexadecimal string.
            for (int i = 0; i < data.Length; i++)
            {
                sBuilder.Append(data[i].ToString("x2"));
            }

            // Return the hexadecimal string.
            return sBuilder.ToString();
        }

        // Verify a hash against a string.
        static bool VerifyMd5Hash(MD5 md5Hash, string input, string hash)
        {
            // Hash the input.
            string hashOfInput = GetMd5Hash(md5Hash, input);

            // Create a StringComparer an compare the hashes.
            StringComparer comparer = StringComparer.OrdinalIgnoreCase;

            if (0 == comparer.Compare(hashOfInput, hash))
            {
                return true;
            }
            else
            {
                return false;
            }
        }

    }
}

// This code example produces the following output:
//
// The MD5 hash of Hello World! is: ed076287532e86365e841e92bfc50d8c.
// Verifying the hash...
// The hashes are the same.

.NET Framework
Available since 1.1
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
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