PHP DES Encryption compatible with Delphi - encryption function

Question

I am trying to create the encrypt PHP algorithm from this thread:

how to sync encryption between delphi and php using dcpcrypt (see shunty's reply)

Here is what I have so far:

function encrypt($str, $key)
{
    $keysize = mcrypt_get_key_size(MCRYPT_DES, MCRYPT_MODE_CBC);

    $ivbytes = array(72, 163, 99, 62, 219, 111, 163, 114);
    $iv = implode(array_map("chr", $ivbytes));

    $pad = ord($str[strlen($str) - 1]);
    $enc = substr($str, 0, strlen($str) - $pad);

    $enc = base64_encode($str);
    $k = mhash(MHASH_SHA1, $key);

    //return substr($dec, 0, strlen($dec) - $pad);
    $dec = mcrypt_encrypt(MCRYPT_DES, substr($k, 0, $keysize), $enc, MCRYPT_MODE_CBC, $iv);

    return $dec;
}

I'm not sure what I'm doing wrong but testing it with this:

echo encrypt("this is a test", "test");

Gives the output: =ž«RCdrç­b˜hý’¯á·OÊ when it should give: WRaG/8xlxqqcTAJ5UAk4DA==

Can anyone help me out in explaining where I am going wrong, would really appreciate the help I can get.

EDIT:

function encrypt_SO($str, $key)
    {
        $keysize = mcrypt_get_key_size(MCRYPT_DES, MCRYPT_MODE_CBC);

        $ivbytes = array(72, 163, 99, 62, 219, 111, 163, 114);
        $iv = implode(array_map("chr", $ivbytes));

        $pad = ord($str[strlen($str) - 1]);
        $enc = substr($str, 0, strlen($str) - $pad);
        $k = mhash(MHASH_SHA1, $key);

        //return substr($dec, 0, strlen($dec) - $pad);
        $dec = mcrypt_encrypt(MCRYPT_DES, substr($k, 0, $keysize), $enc, MCRYPT_MODE_CBC, $iv);

        return base64_encode($dec);
    }

Moved the encoding to the end.

EDIT 2: Solution thanks to everyone's helpful posts:

function encrypt_SO($str, $key)
{
    $keysize = mcrypt_get_key_size(MCRYPT_DES, MCRYPT_MODE_CBC);

    $ivbytes = array(72, 163, 99, 62, 219, 111, 163, 114);
    $iv = implode(array_map("chr", $ivbytes));

    $k = mhash(MHASH_SHA1, $key);

    $blocksize = mcrypt_get_block_size(MCRYPT_DES, MCRYPT_MODE_CBC);
    $padsize = $blocksize - (strlen($str) % $blocksize);
    $str .= str_repeat(chr($padsize), $padsize);

    return base64_encode(mcrypt_encrypt(MCRYPT_DES, substr($k, 0, $keysize), $str, MCRYPT_MODE_CBC, $iv));
}

Answer 1

To answer your comment above:

Encrypt:

• Get keysize and blocksize
• Get IV - this should really be something random and properly generated but to work with DCPcrypt without specifying an IV manually you need to use the one provided.
• Hash the key

• Add the padding - you've got this bit wrong. For this example you need something like:
  

  $blocksize = mcrypt_get_block_size(MCRYPT_DES, MCRYPT_MODE_CBC);
  $padsize = $blocksize - (strlen($str) % $blocksize);
  $str .= str_repeat(chr($padsize), $padsize);
  

• Encrypt

• Base64 encode

Decrypt:

• Get keysize
• Get IV - as above (must be the same as the one used to encrypt but, again, should really be properly cryptographically generated).
• Hash the key
• Base64 decode
• Decrypt
• Remove the padding