/** * Decrypt a RC2 encrypted string * * @param string $text A RC2 encrypted string * @return boolean Returns true */ public function decrypt(&$text) { $this->operation(parent::DECRYPT); // first split up the message into four 16 bit parts (2 bytes), // then convert each array element to an integer $w = self::splitBytes($text); $k = self::splitBytes($this->xkey); $j = 0; // the key index for ($i = 15; $i >= 0; --$i) { $j = $i * 4; /* This is where it gets ugly, RC2 relies on unsigned ints. PHP does * not have a nice way to handle unsigned ints, so we have to rely on sprintf. * To make RC2 compatible with mCrypt, I also forced everything to 32 bit * When I test against mcrypt and the original rc2 C source, I get 32 bit * results, even on a 64 bit platform */ $w[3] &= 65535; $w[3] = parent::uInt($w[3] << 11) + parent::uInt($w[3] >> 5); $w[3] -= parent::uInt($w[0] & ~$w[2]) + parent::uInt($w[1] & $w[2]) + $k[$j + 3]; $w[3] = parent::uInt32($w[3]); $w[2] &= 65535; $w[2] = parent::uInt($w[2] << 13) + parent::uInt($w[2] >> 3); $w[2] -= parent::uInt($w[3] & ~$w[1]) + parent::uInt($w[0] & $w[1]) + $k[$j + 2]; $w[2] = parent::uInt32($w[2]); $w[1] &= 65535; $w[1] = parent::uInt($w[1] << 14) + parent::uInt($w[1] >> 2); $w[1] -= parent::uInt($w[2] & ~$w[0]) + parent::uInt($w[3] & $w[0]) + $k[$j + 1]; $w[1] = parent::uInt32($w[1]); $w[0] &= 65535; $w[0] = parent::uInt($w[0] << 15) + parent::uInt($w[0] >> 1); $w[0] -= parent::uInt($w[1] & ~$w[3]) + parent::uInt($w[2] & $w[3]) + $k[$j + 0]; $w[0] = parent::uInt32($w[0]); if ($i == 5 || $i == 11) { $w[3] -= $k[$w[2] & 63]; $w[2] -= $k[$w[1] & 63]; $w[1] -= $k[$w[0] & 63]; $w[0] -= $k[$w[3] & 63]; } } /* I am not clear why this is required. It was not mentioned * in any of the documentation I read, however reading the original RC2 C * source code, this was done and in order for me to get the * correct results in PHP I needed to do this as well */ $max = count($w); for ($i = 0; $i < $max; ++$i) { $pos = $i * 2; $text[$pos] = chr($w[$i]); $text[$pos + 1] = chr($w[$i] >> 8); } return true; }
/** * The code for this function was translated to PHP from mcrypt's enigma.c, * I was not able to find sufficient documentation to create my own * version of this function. * Enigma requires a 13 byte key, this function will * lengthen the key to get it to 13 bytes long if it's short. It also * Sets $deck, and $t1, $t2, $t3 which I think are the Enigma rotors. * * @return void */ private function createKey() { $this->deck = array(); $this->t1 = array(); $this->t2 = array_fill(0, self::ROTORSZ, 0); $this->t3 = $this->t2; $this->xkey = $this->key(); $klen = $this->keySize(); // get the key to exactly 13 bytes if it's less than 13 if ($klen < 13) { $this->xkey = str_pad($this->xkey, 13, chr(0), STR_PAD_RIGHT); } $seed = 123; for ($i = 0; $i < 13; ++$i) { $seed = parent::sInt32($seed) * ord($this->xkey[$i]) + $i; } // sets $t1 and $deck for ($i = 0; $i < self::ROTORSZ; ++$i) { $this->t1[] = $i; $this->deck[] = $i; } // sets $t3 for ($i = 0; $i < self::ROTORSZ; ++$i) { // make sure the return values are 32 bit $seed = 5 * parent::sInt32($seed) + ord($this->xkey[$i % 13]); $seed = parent::sInt32($seed); // force the returned value to be an unsigned int //$random = parent::uint32($seed % 65521); $random = parent::uInt($seed % 65521); $k = self::ROTORSZ - 1 - $i; $ic = ($random & self::MASK) % ($k + 1); // make sure the returned value is an unsigned int $random = parent::uInt($random >> 8); $temp = $this->t1[$k]; $this->t1[$k] = $this->t1[$ic]; $this->t1[$ic] = $temp; if ($this->t3[$k] != 0) { continue; } $ic = ($random & self::MASK) % $k; while ($this->t3[$ic] != 0) { $ic = ($ic + 1) % $k; } $this->t3[$k] = $ic; $this->t3[$ic] = $k; } // sets $t2 for ($i = 0; $i < self::ROTORSZ; ++$i) { $pos = $this->t1[$i] & self::MASK; $this->t2[$pos] = $i; } // now convert $t1, $t2, $t3, $deck values to signed chars, // PHP's chr() function returns an unsigned char, so we have // to use use our own $this->t1 = array_map("parent::sChar", $this->t1); $this->t2 = array_map("parent::sChar", $this->t2); $this->t3 = array_map("parent::sChar", $this->t3); $this->deck = array_map("parent::sChar", $this->deck); }