A VB.NET equivalent of a PHP hash function

[francosacchi]

I am having trouble converting this PHP code to VB.

$result = hash('sha256', $postdata, true) 

this function can be consulted at this address http://php.net/manual/en/function.hash.php

I have this VB code:

    Public Function SHA256(ByVal Content As String, ByVal raw_output As Boolean) As String
        Dim MoLeCuL3 As New Security.Cryptography.SHA256CryptoServiceProvider
        Dim ByteString() As Byte = System.Text.Encoding.ASCII.GetBytes(Content)
        ByteString = MoLeCuL3.ComputeHash(ByteString)

        Dim FinalString As String = Nothing
        For Each bt As Byte In ByteString
            If raw_output Then
                '..... ????? ..........
            Else
                FinalString &= bt.ToString("x2")
            End If
        Next

        Return FinalString
    End Function

but I can not code the result in "raw binary data", as does the original PHP function with the third parameter set to TRUE.
Can anyone help me with this? Very much appreciated. Thank you.

[jmcilhinney]

Hashing is performed on Byte arrays. The Byte array is the "raw binary data". Where the source Byte array comes from (file, text, Image, etc) is irrelevant to the hashing process, as is where the resultant Byte array goes to. In your VB code, ByteString (which is a poor name) contains the raw binary data that you want.

You can't really have a single method that returns either a String or a Byte array unless you declare the return type as Object, which is a fairly bad idea. I'd suggest two methods: one that returns a String and one that returns a Byte array. The first of those would call the second and convert the Byte array to a hex string.

[Sitten Spynne]

Yeah, what you're asking for is considered bad practice in VB. PHP is a loosely-typed dynamic language and, for years, was designed by monkeys, so the convention is to return many different types from functions and to not always document every case. In VB .NET, you have to up-front declare your return type and write code that provably returns that type.

So in VB .NET, I'd expect an API surface like this:

Function GetSHA256(...) As Byte()
    ' <do the things to get the byte array>
End Function

Function GetSHA256AsString(...) As String
    Dim bytes() As Byte = GetSHA256(...)
    ' <do the things to convert the byte array to a String>
End Function

There are a couple of other ways to make it nice, but that is the simplest approach. You could, for example, make a type to help out:

Public Class SHA256Data

    Public Property Hash() As Byte()
    Public Property HashString() As String

End Class

Then you can write one function that returns both things:

Function GetSHA256(...) As SHA256Data
    Dim hashBytes() As Byte
    ' <do the thing to set hashBytes to the proper hash bytes>
    Dim hashString As String
    ' <do the thing to set hashString to the right String

    Return New SHA256Data() With {
        .Hash = hashBytes,
        .HashString = hashString
    }
End Function