<?php
declare(strict_types=1);
/*
* The MIT License (MIT)
*
* Copyright (c) 2014-2021 Spomky-Labs
*
* This software may be modified and distributed under the terms
* of the MIT license. See the LICENSE file for details.
*/
namespace Cose\Key;
use function array_key_exists;
use Assert\Assertion;
use FG\ASN1\ExplicitlyTaggedObject;
use FG\ASN1\Universal\BitString;
use FG\ASN1\Universal\Integer;
use FG\ASN1\Universal\ObjectIdentifier;
use FG\ASN1\Universal\OctetString;
use FG\ASN1\Universal\Sequence;
class Ec2Key extends Key
{
public const CURVE_P256 = 1;
public const CURVE_P256K = 8;
public const CURVE_P384 = 2;
public const CURVE_P521 = 3;
public const DATA_CURVE = -1;
public const DATA_X = -2;
public const DATA_Y = -3;
public const DATA_D = -4;
private const SUPPORTED_CURVES = [
self::CURVE_P256,
self::CURVE_P256K,
self::CURVE_P384,
self::CURVE_P521,
];
private const NAMED_CURVE_OID = [
self::CURVE_P256 => '1.2.840.10045.3.1.7', // NIST P-256 / secp256r1
self::CURVE_P256K => '1.3.132.0.10', // NIST P-256K / secp256k1
self::CURVE_P384 => '1.3.132.0.34', // NIST P-384 / secp384r1
self::CURVE_P521 => '1.3.132.0.35', // NIST P-521 / secp521r1
];
private const CURVE_KEY_LENGTH = [
self::CURVE_P256 => 32,
self::CURVE_P256K => 32,
self::CURVE_P384 => 48,
self::CURVE_P521 => 66,
];
public function __construct(array $data)
{
parent::__construct($data);
Assertion::eq($data[self::TYPE], self::TYPE_EC2, 'Invalid EC2 key. The key type does not correspond to an EC2 key');
Assertion::keyExists($data, self::DATA_CURVE, 'Invalid EC2 key. The curve is missing');
Assertion::keyExists($data, self::DATA_X, 'Invalid EC2 key. The x coordinate is missing');
Assertion::keyExists($data, self::DATA_Y, 'Invalid EC2 key. The y coordinate is missing');
Assertion::length($data[self::DATA_X], self::CURVE_KEY_LENGTH[$data[self::DATA_CURVE]], 'Invalid length for x coordinate', null, '8bit');
Assertion::length($data[self::DATA_Y], self::CURVE_KEY_LENGTH[$data[self::DATA_CURVE]], 'Invalid length for y coordinate', null, '8bit');
Assertion::inArray((int) $data[self::DATA_CURVE], self::SUPPORTED_CURVES, 'The curve is not supported');
}
public function toPublic(): self
{
$data = $this->getData();
unset($data[self::DATA_D]);
return new self($data);
}
public function x(): string
{
return $this->get(self::DATA_X);
}
public function y(): string
{
return $this->get(self::DATA_Y);
}
public function isPrivate(): bool
{
return array_key_exists(self::DATA_D, $this->getData());
}
public function d(): string
{
Assertion::true($this->isPrivate(), 'The key is not private');
return $this->get(self::DATA_D);
}
public function curve(): int
{
return (int) $this->get(self::DATA_CURVE);
}
public function asPEM(): string
{
if ($this->isPrivate()) {
$der = new Sequence(
new Integer(1),
new OctetString(bin2hex($this->d())),
new ExplicitlyTaggedObject(0, new ObjectIdentifier($this->getCurveOid())),
new ExplicitlyTaggedObject(1, new BitString(bin2hex($this->getUncompressedCoordinates())))
);
return $this->pem('EC PRIVATE KEY', $der->getBinary());
}
$der = new Sequence(
new Sequence(
new ObjectIdentifier('1.2.840.10045.2.1'),
new ObjectIdentifier($this->getCurveOid())
),
new BitString(bin2hex($this->getUncompressedCoordinates()))
);
return $this->pem('PUBLIC KEY', $der->getBinary());
}
public function getUncompressedCoordinates(): string
{
return "\x04".$this->x().$this->y();
}
private function getCurveOid(): string
{
return self::NAMED_CURVE_OID[$this->curve()];
}
private function pem(string $type, string $der): string
{
return sprintf("-----BEGIN %s-----\n", mb_strtoupper($type)).
chunk_split(base64_encode($der), 64, "\n").
sprintf("-----END %s-----\n", mb_strtoupper($type));
}
}