HashAlgorithm.TransformFinalBlock(Byte[], Int32, Int32) Method

Definition

Computes the hash value for the specified region of the specified byte array.

C#
public byte[] TransformFinalBlock(byte[] inputBuffer, int inputOffset, int inputCount);

Parameters

inputBuffer
Byte[]

The input to compute the hash code for.

inputOffset
Int32

The offset into the byte array from which to begin using data.

inputCount
Int32

The number of bytes in the byte array to use as data.

Returns

Byte[]

An array that is a copy of the part of the input that is hashed.

Implements

Exceptions

inputCount uses an invalid value.

-or-

inputBuffer has an invalid offset length.

inputBuffer is null.

inputOffset is out of range. This parameter requires a non-negative number.

The object has already been disposed.

Examples

The following code examples use the TransformFinalBlock method with the TransformBlock method to hash a string.

C#
using System;
using System.Security.Cryptography;
using System.Text;

class MainClass
{
    public static void Main()
    {
        RandomNumberGenerator rnd = RandomNumberGenerator.Create();

        byte[] input = new byte[20];
        rnd.GetBytes(input);

        Console.WriteLine("Input        : {0}\n", BytesToStr(input));
        PrintHash(input);
        PrintHashOneBlock(input);
        PrintHashMultiBlock(input, 1);
        PrintHashMultiBlock(input, 2);
        PrintHashMultiBlock(input, 3);
        PrintHashMultiBlock(input, 5);
        PrintHashMultiBlock(input, 10);
        PrintHashMultiBlock(input, 11);
        PrintHashMultiBlock(input, 19);
        PrintHashMultiBlock(input, 20);
        PrintHashMultiBlock(input, 21);
    }

    public static string BytesToStr(byte[] bytes)
    {
        StringBuilder str = new StringBuilder();

        for (int i = 0; i < bytes.Length; i++)
            str.AppendFormat("{0:X2}", bytes[i]);

        return str.ToString();
    }

    public static void PrintHash(byte[] input)
    {
        SHA256Managed sha = new SHA256Managed();
        Console.WriteLine("ComputeHash  : {0}", BytesToStr(sha.ComputeHash(input)));
    }

    public static void PrintHashOneBlock(byte[] input)
    {
        SHA256Managed sha = new SHA256Managed();
        sha.TransformFinalBlock(input, 0, input.Length);
        Console.WriteLine("FinalBlock   : {0}", BytesToStr(sha.Hash));
    }

    public static void PrintHashMultiBlock(byte[] input, int size)
    {
        SHA256Managed sha = new SHA256Managed();
        int offset = 0;

        while (input.Length - offset >= size)
            offset += sha.TransformBlock(input, offset, size, input, offset);

        sha.TransformFinalBlock(input, offset, input.Length - offset);
        Console.WriteLine("MultiBlock {0:00}: {1}", size, BytesToStr(sha.Hash));
    }
}
/*
This example produces output similar to the following:

Input        : 45D97219908A572DE336B9DEC787C311D3349F69

ComputeHash  : 84E87322C7E3BCA848B0A698EE66E9A9725DA786F9FD4FFD46C385F59AB35B15
FinalBlock   : 84E87322C7E3BCA848B0A698EE66E9A9725DA786F9FD4FFD46C385F59AB35B15
MultiBlock 01: 84E87322C7E3BCA848B0A698EE66E9A9725DA786F9FD4FFD46C385F59AB35B15
MultiBlock 02: 84E87322C7E3BCA848B0A698EE66E9A9725DA786F9FD4FFD46C385F59AB35B15
MultiBlock 03: 84E87322C7E3BCA848B0A698EE66E9A9725DA786F9FD4FFD46C385F59AB35B15
MultiBlock 05: 84E87322C7E3BCA848B0A698EE66E9A9725DA786F9FD4FFD46C385F59AB35B15
MultiBlock 10: 84E87322C7E3BCA848B0A698EE66E9A9725DA786F9FD4FFD46C385F59AB35B15
MultiBlock 11: 84E87322C7E3BCA848B0A698EE66E9A9725DA786F9FD4FFD46C385F59AB35B15
MultiBlock 19: 84E87322C7E3BCA848B0A698EE66E9A9725DA786F9FD4FFD46C385F59AB35B15
MultiBlock 20: 84E87322C7E3BCA848B0A698EE66E9A9725DA786F9FD4FFD46C385F59AB35B15
MultiBlock 21: 84E87322C7E3BCA848B0A698EE66E9A9725DA786F9FD4FFD46C385F59AB35B15

*/

Remarks

You must call the TransformFinalBlock method after calling the TransformBlock method but before you retrieve the final hash value.

Note that the return value of this method is not the hash value, but only a copy of the hashed part of the input data. To retrieve the final hashed value after calling the TransformFinalBlock method, get the byte array contained in the Hash property.

Applies to

Product Versions
.NET Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9
.NET Framework 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard 2.0, 2.1