<?php
declare(strict_types=1);
namespace ParagonIE\HPKE\AEAD;
use ParagonIE\HPKE\HPKEException;
use ParagonIE\HPKE\Interfaces\AEADInterface;
use ParagonIE\HPKE\SymmetricKey;
class AES256GCM implements AEADInterface
{
const AEAD_ID = "\x00\x02";
public function getAeadId(): string
{
return self::AEAD_ID;
}
public function keyLength(): int
{
return 32;
}
public function nonceLength(): int
{
return 12;
}
public function tagLength(): int
{
return 16;
}
public function encrypt(
#[\SensitiveParameter] SymmetricKey $key,
#[\SensitiveParameter] string $plaintext,
string $nonce,
string $aad = ''
): array {
$tag = '';
$ciphertext = openssl_encrypt(
$plaintext,
'aes-256-gcm',
$key->bytes,
OPENSSL_RAW_DATA | OPENSSL_NO_PADDING,
$nonce,
$tag,
$aad
);
return [$ciphertext, $tag];
}
/**
* @throws HPKEException
*/
public function decrypt(
#[\SensitiveParameter] SymmetricKey $key,
string $ciphertext,
string $tag,
string $nonce,
string $aad = ''
): string {
$result = openssl_decrypt(
$ciphertext,
'aes-256-gcm',
$key->bytes,
OPENSSL_RAW_DATA | OPENSSL_NO_PADDING,
$nonce,
$tag,
$aad
);
if (!is_string($result)) {
throw new HPKEException('Decryption error');
}
return $result;
}
}
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