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HashAlgorithm.TransformBlock Method

Computes the hash value for the specified region of the input byte array and copies the resulting hash value to the specified region of the output byte array.

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

public int TransformBlock (
	byte[] inputBuffer,
	int inputOffset,
	int inputCount,
	byte[] outputBuffer,
	int outputOffset
)
public final int TransformBlock (
	byte[] inputBuffer, 
	int inputOffset, 
	int inputCount, 
	byte[] outputBuffer, 
	int outputOffset
)
public final function TransformBlock (
	inputBuffer : byte[], 
	inputOffset : int, 
	inputCount : int, 
	outputBuffer : byte[], 
	outputOffset : int
) : int
Not applicable.

Parameters

inputBuffer

The input to compute the hash code for.

inputOffset

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

inputCount

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

outputBuffer

A copy of the part of the input array used to compute the hash code.

outputOffset

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

Return Value

The number of bytes written.

Exception typeCondition

ArgumentException

inputCount uses an invalid value.

-or-

inputBuffer has an invalid length.

ArgumentNullException

inputBuffer is a null reference (Nothing in Visual Basic).

ArgumentOutOfRangeException

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

ObjectDisposedException

The object has already been disposed.

You must call the TransformBlock method before calling the TransformFinalBlock method. You must call both methods before you retrieve the final hash value.

To retrieve the final hash value after calling the TransformFinalBlock method, get the byte array contained within the Hash property.

Calling the TransformBlock method with different input and output arrays results in an IOException.

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));
	}

}

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0

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