src/Bitpay/PublicKey.php
<?php
/**
* @license Copyright 2011-2014 BitPay Inc., MIT License
* see https://github.com/bitpay/php-bitpay-client/blob/master/LICENSE
*/
namespace Bitpay;
use Bitpay\Math\Math;
use Bitpay\Util\Secp256k1;
use Bitpay\Util\Util;
/**
* @package Bitcore
*/
class PublicKey extends Key
{
/**
* @var SinKey
*/
protected $sin;
/**
* @var PrivateKey
*/
protected $privateKey;
/**
* Returns the compressed public key value
*
* @return string
*/
public function __toString()
{
if (is_null($this->x)) {
return '';
}
if (Math::mod('0x'.$this->y, '0'.'x02') == '1') {
return sprintf('03%s', $this->x);
} else {
return sprintf('02%s', $this->x);
}
}
/**
* @param PrivateKey
*/
public static function createFromPrivateKey(PrivateKey $private)
{
$public = new self();
$public->setPrivateKey($private);
return $public;
}
/**
* @return KeyInterface
*/
public function setPrivateKey(PrivateKey $privateKey)
{
$this->privateKey = $privateKey;
return $this;
}
/**
* Generates an uncompressed and compressed EC public key.
*
* @param \Bitpay\PrivateKey $privateKey
*
* @return Bitpay\PublicKey
*/
public function generate(PrivateKey $privateKey = null)
{
if ($privateKey instanceof PrivateKey) {
$this->setPrivateKey($privateKey);
}
if (!empty($this->hex)) {
return $this;
}
if (is_null($this->privateKey)) {
throw new \Exception('Please `setPrivateKey` before you generate a public key');
}
if (!$this->privateKey->isGenerated()) {
$this->privateKey->generate();
}
if (!$this->privateKey->isValid()) {
throw new \Exception('Private Key is invalid and cannot be used to generate a public key');
}
$point = new Point(
'0x'.substr(Secp256k1::G, 2, 64),
'0x'.substr(Secp256k1::G, 66, 64)
);
$R = Util::doubleAndAdd(
'0x'.$this->privateKey->getHex(),
$point
);
$RxHex = Util::encodeHex($R->getX());
$RyHex = Util::encodeHex($R->getY());
$RxHex = str_pad($RxHex, 64, '0', STR_PAD_LEFT);
$RyHex = str_pad($RyHex, 64, '0', STR_PAD_LEFT);
$this->x = $RxHex;
$this->y = $RyHex;
$this->hex = sprintf('%s%s', $RxHex, $RyHex);
$this->dec = Util::decodeHex($this->hex);
return $this;
}
/**
* Checks to see if the public key is not blank and contains
* valid decimal and hex valules for this->hex & this->dec
*
* @return boolean
*/
public function isValid()
{
return ((!empty($this->hex) && ctype_xdigit($this->hex)) && (!empty($this->dec) && ctype_digit($this->dec)));
}
/**
* @return SinKey
*/
public function getSin()
{
if (empty($this->hex)) {
$this->generate();
}
if (null === $this->sin) {
$this->sin = new SinKey();
$this->sin->setPublicKey($this);
$this->sin->generate();
}
return $this->sin;
}
}