<?php
declare(strict_types=1);
namespace ParagonIE\HPKE\KEM\DHKEM;
use Mdanter\Ecc\Crypto\Key\{
PublicKey,
PublicKeyInterface
};
use Mdanter\Ecc\Exception\InsecureCurveException;
use Mdanter\Ecc\Math\ConstantTimeMath;
use Mdanter\Ecc\Primitives\PointInterface;
use Mdanter\Ecc\Serializer\Point\UncompressedPointSerializer;
use ParagonIE\EasyECC\Curve25519\MontgomeryPublicKey;
use ParagonIE\HPKE\HPKEException;
use ParagonIE\HPKE\Interfaces\EncapsKeyInterface;
use SodiumException;
class EncapsKey implements EncapsKeyInterface
{
/**
* @throws HPKEException
*/
public function __construct(
public readonly Curve $curve,
#[\SensitiveParameter]
public readonly string $bytes
){
if (strlen($this->bytes) !== $this->curve->encapsKeyLength()) {
throw new HPKEException('Invalid public key length');
}
}
/**
* @throws HPKEException
* @throws InsecureCurveException
* @throws SodiumException
*/
public function toPublicKey(): PublicKeyInterface
{
if ($this->curve === Curve::X25519) {
return new MontgomeryPublicKey($this->bytes);
}
return new PublicKey(
new ConstantTimeMath(),
$this->curve->getGenerator(),
$this->getPoint()
);
}
/**
* @throws HPKEException
* @throws InsecureCurveException
* @throws SodiumException
*/
public function getPoint(): PointInterface
{
if ($this->curve === Curve::X25519) {
throw new HPKEException('Calling getPoint() on X25519 is unexpected');
}
$serializer = new UncompressedPointSerializer();
return $serializer->unserialize($this->curve->getCurveFp(), sodium_bin2hex($this->bytes));
}
/**
* @throws HPKEException
* @throws InsecureCurveException
* @throws SodiumException
*/
public function serializeForHeader(): string
{
if ($this->curve === Curve::X25519) {
return $this->bytes;
}
$serializer = new UncompressedPointSerializer();
return sodium_hex2bin($serializer->serialize($this->getPoint()));
}
}
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