Convert vb.net byte to php

Question

I have the following code in VB.net

Dim bytIV() As Byte = {121, 241, 10, 1, 132, 74, 11, 39, 255, 91, 45, 78, 14, 211, 22, 62}

I'm trying to convert it to php.

$iv = array(121, 241, 10, 1, 132, 74, 11, 39, 255, 91, 45, 78, 14, 211, 22, 62);

That doesn't work.

The complete php code below:

    <?php
    $key = "lvvxmzmfrqeephxwmifwvyyllivhzbdi";
    $input = "this is a secret keythis is a secret keythis is a secret keythis is a secret key";

    $td = mcrypt_module_open('rijndael-128', '', 'ofb', '');
    //$iv = mcrypt_create_iv (mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
    $iv = array(121, 241, 10, 1, 132, 74, 11, 39, 255, 91, 45, 78, 14, 211, 22, 62);
    mcrypt_generic_init($td, $key, $iv);
    $encrypted_data = mcrypt_generic($td, $input);
    mcrypt_generic_deinit($td);
    mcrypt_module_close($td);

    echo "IV: $iv <br><br>";

    echo  base64_encode($encrypted_data);
?>

VB.net code:

Public Function DecryptString128Bit(ByVal vstrStringToBeDecrypted As String, _
                                    ByVal vstrDecryptionKey As String) As String

    Dim bytDataToBeDecrypted() As Byte
    Dim bytTemp() As Byte
    Dim bytIV() As Byte = {121, 241, 10, 1, 132, 74, 11, 39, 255, 91, 45, 78, 14, 211, 22, 62}
    Dim objRijndaelManaged As New RijndaelManaged()
    Dim objMemoryStream As MemoryStream
    Dim objCryptoStream As CryptoStream
    Dim bytDecryptionKey() As Byte

    Dim intLength As Integer
    Dim intRemaining As Integer
    Dim intCtr As Integer
    Dim strReturnString As String = String.Empty
    Dim achrCharacterArray() As Char
    Dim intIndex As Integer

    '   *****************************************************************
    '   ******   Convert base64 encrypted value to byte array      ******
    '   *****************************************************************

    bytDataToBeDecrypted = Convert.FromBase64String(vstrStringToBeDecrypted)

    '   ********************************************************************
    '   ******   Encryption Key must be 256 bits long (32 bytes)      ******
    '   ******   If it is longer than 32 bytes it will be truncated.  ******
    '   ******   If it is shorter than 32 bytes it will be padded     ******
    '   ******   with upper-case Xs.                                  ****** 
    '   ********************************************************************

    intLength = Len(vstrDecryptionKey)

    If intLength >= 32 Then
        vstrDecryptionKey = Strings.Left(vstrDecryptionKey, 32)
    Else
        intLength = Len(vstrDecryptionKey)
        intRemaining = 32 - intLength
        vstrDecryptionKey = vstrDecryptionKey & Strings.StrDup(intRemaining, "X")
    End If

    bytDecryptionKey = Encoding.ASCII.GetBytes(vstrDecryptionKey.ToCharArray)

    ReDim bytTemp(bytDataToBeDecrypted.Length)

    objMemoryStream = New MemoryStream(bytDataToBeDecrypted)

    '   ***********************************************************************
    '   ******  Create the decryptor and write value to it after it is   ******
    '   ******  converted into a byte array                              ******
    '   ***********************************************************************

    Try

        objCryptoStream = New CryptoStream(objMemoryStream, _
           objRijndaelManaged.CreateDecryptor(bytDecryptionKey, bytIV), _
           CryptoStreamMode.Read)

        objCryptoStream.Read(bytTemp, 0, bytTemp.Length)

        objCryptoStream.FlushFinalBlock()
        objMemoryStream.Close()
        objCryptoStream.Close()

    Catch

    End Try

    '   *****************************************
    '   ******   Return decypted value     ******
    '   *****************************************

    Return StripNullCharacters(Encoding.ASCII.GetString(bytTemp))

End Function


Public Function StripNullCharacters(ByVal vstrStringWithNulls As String) As String

    Dim intPosition As Integer
    Dim strStringWithOutNulls As String

    intPosition = 1
    strStringWithOutNulls = vstrStringWithNulls

    Do While intPosition > 0
        intPosition = InStr(intPosition, vstrStringWithNulls, vbNullChar)

        If intPosition > 0 Then
            strStringWithOutNulls = Left$(strStringWithOutNulls, intPosition - 1) & _
                              Right$(strStringWithOutNulls, Len(strStringWithOutNulls) - intPosition)
        End If

        If intPosition > strStringWithOutNulls.Length Then
            Exit Do
        End If
    Loop

    Return strStringWithOutNulls

End Function

Answer 1

The line that you say isn't working actually works fine. I have never used PHP pre version 3, but it has worked since then at least.

The problem is that the $iv parameter of mcrypt_generic_init is supposed to be a string, not an array of ints.

This should work for conversion:

$iv_string = "";
foreach ($iv as $char)
    $iv_string .= chr($char);

Sorry, my PHP is rusty :)

Answer 2

PHP expects the IV to be a string, not an array - which will be cast to the string "Array".

I'm guessing that the string is just binary data and the pack() function may be what you need. It doesn't accept an array as a parameter, but one of the comments uses a loop through the array to concatenate the packed values of each array element.