Hautelook\Phpass\PasswordHash::gensalt_blowfish PHP Method

    public function gensalt_blowfish($input)
    {
        // This one needs to use a different order of characters and a
        // different encoding scheme from the one in encode64() above.
        // We care because the last character in our encoded string will
        // only represent 2 bits.  While two known implementations of
        // bcrypt will happily accept and correct a salt string which
        // has the 4 unused bits set to non-zero, we do not want to take
        // chances and we also do not want to waste an additional byte
        // of entropy.
        $itoa64 = './ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
        $output = '$2a$';
        $output .= chr(ord('0') + $this->iteration_count_log2 / 10);
        $output .= chr(ord('0') + $this->iteration_count_log2 % 10);
        $output .= '$';
        $i = 0;
        do {
            $c1 = ord($input[$i++]);
            $output .= $itoa64[$c1 >> 2];
            $c1 = ($c1 & 0x3) << 4;
            if ($i >= 16) {
                $output .= $itoa64[$c1];
                break;
            }
            $c2 = ord($input[$i++]);
            $c1 |= $c2 >> 4;
            $output .= $itoa64[$c1];
            $c1 = ($c2 & 0xf) << 2;
            $c2 = ord($input[$i++]);
            $c1 |= $c2 >> 6;
            $output .= $itoa64[$c1];
            $output .= $itoa64[$c2 & 0x3f];
        } while (1);
        return $output;
    }