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HashAlgorithm.ComputeHash Method (Byte())

Computes the hash value for the specified byte array.

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

'Declaration
Public Function ComputeHash ( _
	buffer As Byte() _
) As Byte()

Parameters

buffer
Type: System.Byte()

The input to compute the hash code for.

Return Value

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

ExceptionCondition
ArgumentNullException

buffer is Nothing.

ObjectDisposedException

The object has already been disposed.

The following example computes the MD5 hash value of a string and returns the hash as a 32-character, hexadecimal-formatted string. The hash string created by this code example is compatible with any MD5 hash function (on any platform) that creates a 32-character, hexadecimal-formatted hash string.

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


Class Program

    Shared Sub Main(ByVal args() As String)
        Dim [source] As String = "Hello World!" 
        Using md5Hash As MD5 = MD5.Create()

            Dim hash As String = GetMd5Hash(md5Hash, source)

            Console.WriteLine("The MD5 hash of " + source + " is: " + hash + ".")

            Console.WriteLine("Verifying the hash...")

            If VerifyMd5Hash(md5Hash, [source], hash) Then
                Console.WriteLine("The hashes are the same.")
            Else
                Console.WriteLine("The hashes are not same.")
            End If 
        End Using 
    End Sub 'Main



    Shared Function GetMd5Hash(ByVal md5Hash As MD5, ByVal input As String) As String 

        ' Convert the input string to a byte array and compute the hash. 
        Dim data As Byte() = md5Hash.ComputeHash(Encoding.UTF8.GetBytes(input))

        ' Create a new Stringbuilder to collect the bytes 
        ' and create a string. 
        Dim sBuilder As New StringBuilder()

        ' Loop through each byte of the hashed data  
        ' and format each one as a hexadecimal string. 
        Dim i As Integer 
        For i = 0 To data.Length - 1
            sBuilder.Append(data(i).ToString("x2"))
        Next i

        ' Return the hexadecimal string. 
        Return sBuilder.ToString()

    End Function 'GetMd5Hash


    ' Verify a hash against a string. 
    Shared Function VerifyMd5Hash(ByVal md5Hash As MD5, ByVal input As String, ByVal hash As String) As Boolean 
        ' Hash the input. 
        Dim hashOfInput As String = GetMd5Hash(md5Hash, input)

        ' Create a StringComparer an compare the hashes. 
        Dim comparer As StringComparer = StringComparer.OrdinalIgnoreCase

        If 0 = comparer.Compare(hashOfInput, hash) Then 
            Return True 
        Else 
            Return False 
        End If 

    End Function 'VerifyMd5Hash
End Class 'Program 
' This code example produces the following output: 

' The MD5 hash of Hello World! is: ed076287532e86365e841e92bfc50d8c. 
' Verifying the hash... 
' The hashes are the same.

.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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