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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 Function TransformFinalBlock ( _
	inputBuffer As Byte(), _
	inputOffset As Integer, _
	inputCount As Integer _
) As Byte()
Dim instance As HashAlgorithm 
Dim inputBuffer As Byte()
Dim inputOffset As Integer 
Dim inputCount As Integer 
Dim returnValue As Byte()

returnValue = instance.TransformFinalBlock(inputBuffer, _
	inputOffset, inputCount)


Type: System.Byte()

The input to compute the hash code for.

Type: System.Int32

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

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.


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


inputCount uses an invalid value.


inputBuffer has an invalid offset length.


inputBuffer is Nothing.


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


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.

Imports System
Imports System.Text
Imports System.Security.Cryptography

Class Program

	Public Shared Sub Main()
		Dim rnd As RandomNumberGenerator = RandomNumberGenerator.Create
		Dim input() As Byte = New Byte((20) - 1) {}
		Console.WriteLine("Input        : {0}"& vbLf, BytesToStr(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)
	End Sub 

	Public Shared Function BytesToStr(ByVal bytes() As Byte) As String 
		Dim str As StringBuilder = New StringBuilder
		Dim i As Integer = 0
		Do While (i < bytes.Length)
		str.AppendFormat("{0:X2}", bytes(i))
		i = (i + 1)
		Return str.ToString
	End Function 

	Public Shared Sub PrintHash(ByVal input() As Byte)
		Dim sha As SHA256Managed = New SHA256Managed
		Console.WriteLine("ComputeHash  : {0}", BytesToStr(sha.ComputeHash(input)))
	End Sub 

	Public Shared Sub PrintHashOneBlock(ByVal input() As Byte)
		Dim sha As SHA256Managed = New SHA256Managed
		sha.TransformFinalBlock(input, 0, input.Length)
		Console.WriteLine("FinalBlock   : {0}", BytesToStr(sha.Hash))
	End Sub 

	Public Shared Sub PrintHashMultiBlock(ByVal input() As Byte, ByVal size As Integer)
		Dim sha As SHA256Managed = New SHA256Managed
		Dim offset As Integer = 0

		While ((input.Length - offset)  _
			>= size)
		offset = (offset + sha.TransformBlock(input, offset, size, input, offset))

		End While
		sha.TransformFinalBlock(input, offset, (input.Length - offset))
		Console.WriteLine("MultiBlock {0:00}: {1}", size, BytesToStr(sha.Hash))
	End Sub 
End Class

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0

Community Additions

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