<?php
declare(strict_types=1);
namespace ParagonIE\Paseto\Keys;
use ParagonIE\ConstantTime\Base64UrlSafe;
use ParagonIE\Paseto\{
ReceivingKey,
SendingKey,
ProtocolInterface,
Protocol\Version1,
Protocol\Version2,
Util
};
/**
* Class SymmetricKey
* @package ParagonIE\Paseto\Keys
*/
class SymmetricKey implements ReceivingKey, SendingKey
{
const INFO_ENCRYPTION = 'paseto-encryption-key';
const INFO_AUTHENTICATION = 'paseto-auth-key-for-aead';
/** @var string $key */
protected $key = '';
/** @var ProtocolInterface $protocol */
protected $protocol;
/**
* SymmetricKey constructor.
*
* @param string $keyMaterial
* @param ProtocolInterface|null $protocol
*/
public function __construct(
string $keyMaterial,
ProtocolInterface $protocol = null
) {
$this->key = $keyMaterial;
$this->protocol = $protocol ?? new Version2;
}
/**
* @param ProtocolInterface|null $protocol
*
* @return SymmetricKey
*/
public static function generate(ProtocolInterface $protocol = null): self
{
$protocol = $protocol ?? new Version2;
return new static(
\random_bytes($protocol::getSymmetricKeyByteLength()),
$protocol
);
}
/**
* @param string $keyMaterial
*
* @return self
* @throws \Exception
* @throws \TypeError
*/
public static function v1(string $keyMaterial): self
{
return new self($keyMaterial, new Version1());
}
/**
* @param string $keyMaterial
*
* @return self
* @throws \Exception
* @throws \TypeError
*/
public static function v2(string $keyMaterial): self
{
return new self($keyMaterial, new Version2());
}
/**
* @return string
* @throws \TypeError
*/
public function encode(): string
{
return Base64UrlSafe::encodeUnpadded($this->key);
}
/**
* @param string $encoded
* @param ProtocolInterface|null $version
* @return self
* @throws \TypeError
*/
public static function fromEncodedString(string $encoded, ProtocolInterface $version = null): self
{
$decoded = Base64UrlSafe::decode($encoded);
return new self($decoded, $version);
}
/**
* @return ProtocolInterface
*/
public function getProtocol(): ProtocolInterface
{
return $this->protocol;
}
/**
* @return string
*/
public function raw(): string
{
return $this->key;
}
/**
* Split this key into two 256-bit keys, using HKDF-SHA384
* (with the given salt)
*
* @param string|null $salt
* @return array<int, string>
*
* @throws \ParagonIE\Paseto\Exception\PasetoException
* @throws \TypeError
*/
public function split(string $salt = null): array
{
$encKey = Util::HKDF(
'sha384',
$this->key,
32,
self::INFO_ENCRYPTION,
$salt
);
$authKey = Util::HKDF(
'sha384',
$this->key,
32,
self::INFO_AUTHENTICATION,
$salt
);
return [$encKey, $authKey];
}
/**
* @return array
*/
public function __debugInfo()
{
return [];
}
}
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