Key Derivation Function.
| public static generate ( string $Z, string $algorithm, integer $encryption_key_size, string $apu = '', string $apv = '' ) : string | ||
| $Z | string | Shared secret |
| $algorithm | string | Encryption algorithm |
| $encryption_key_size | integer | Size of the encryption key |
| $apu | string | Agreement PartyUInfo (information about the producer) |
| $apv | string | Agreement PartyVInfo (information about the recipient) |
| return | string | |
/**
* {@inheritdoc}
*/
public function getAgreementKey($encryption_key_length, $algorithm, JWKInterface $recipient_key, array $complete_header = [], array &$additional_header_values = [])
{
if ($recipient_key->has('d')) {
$this->checkKey($recipient_key, true);
$private_key = $recipient_key;
$public_key = $this->getPublicKey($complete_header);
} else {
$this->checkKey($recipient_key, false);
$public_key = $recipient_key;
switch ($public_key->get('crv')) {
case 'P-256':
case 'P-384':
case 'P-521':
$private_key = JWKFactory::createECKey(['crv' => $public_key->get('crv')]);
break;
case 'X25519':
$private_key = JWKFactory::createOKPKey(['crv' => 'X25519']);
break;
default:
throw new \InvalidArgumentException(sprintf('The curve "%s" is not supported', $public_key->get('crv')));
}
$epk = $private_key->toPublic()->getAll();
$additional_header_values = array_merge($additional_header_values, ['epk' => $epk]);
}
Assertion::eq($private_key->get('crv'), $public_key->get('crv'), 'Curves are different');
$agreed_key = $this->calculateAgreementKey($private_key, $public_key);
$apu = array_key_exists('apu', $complete_header) ? $complete_header['apu'] : '';
$apv = array_key_exists('apv', $complete_header) ? $complete_header['apv'] : '';
return ConcatKDF::generate($agreed_key, $algorithm, $encryption_key_length, $apu, $apv);
}
/**
* {@inheritdoc}
*/
public function getAgreementKey($encryption_key_length, JWKInterface $private_key, JWKInterface $public_key = null, array $complete_header = [], array &$additional_header_values = [])
{
$this->checkKey($private_key, true);
if (null === $public_key) {
$public_key = $this->getPublicKey($complete_header);
} else {
$this->checkKey($public_key, false);
$additional_header_values = array_merge($additional_header_values, ['epk' => ['kty' => $private_key->get('kty'), 'crv' => $private_key->get('crv'), 'x' => $private_key->get('x'), 'y' => $private_key->get('y')]]);
}
if ($private_key->get('crv') !== $public_key->get('crv')) {
throw new \InvalidArgumentException('Curves are different');
}
$agreed_key = $this->calculateAgreementKey($private_key, $public_key);
$apu = array_key_exists('apu', $complete_header) ? $complete_header['apu'] : '';
$apv = array_key_exists('apv', $complete_header) ? $complete_header['apv'] : '';
return ConcatKDF::generate($this->convertDecToBin($agreed_key), $complete_header['enc'], $encryption_key_length, $apu, $apv);
}