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HashAlgorithm.TransformFinalBlock Method

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

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

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

Parameters

inputBuffer
Type: System.Byte[]

The input to compute the hash code for.

inputOffset
Type: System.Int32

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

inputCount
Type: System.Int32

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

Return Value

Type: System.Byte[]
An array that is a copy of the part of the input that is hashed.

Implements

ICryptoTransform.TransformFinalBlock(Byte[], Int32, Int32)

ExceptionCondition
ArgumentException

inputCount uses an invalid value.

-or-

inputBuffer has an invalid offset length.

ArgumentNullException

inputBuffer is null.

ArgumentOutOfRangeException

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

ObjectDisposedException

The object has already been disposed.

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.

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

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));
	}

}

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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