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HashAlgorithm.ComputeHash Method (Byte(), Int32, Int32)

Updated: December 2008

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

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

Public Function ComputeHash ( _
	buffer As Byte(), _
	offset As Integer, _
	count As Integer _
) As Byte()
Dim instance As HashAlgorithm 
Dim buffer As Byte()
Dim offset As Integer 
Dim count As Integer 
Dim returnValue As Byte()

returnValue = instance.ComputeHash(buffer, _
	offset, count)


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 array to use as data.

Return Value

Type: System.Byte()
The computed hash code.


count is an invalid value.


buffer length is invalid.


buffer is Nothing.


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


The object has already been disposed.

The size of the hash value depends on the hash algorithm it is computed for. For example, the size of the hash for the HMACSHA384 algorithm is 384 bits, and the size of the hash for the HMACSHA256 algorithm is 256 bits. You can obtain the size of the hash in bits by calling the HashSize property. For more information about hash codes, see Ensuring Data Integrity with Hash Codes.

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




December 2008

Added remarks about the size of the hash value and where to obtain more information.

Customer feedback.