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<?php |
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declare(strict_types = 1); |
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namespace Sop\GCM\Cipher\AES; |
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use Sop\GCM\Cipher\Cipher; |
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/** |
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* Base class for AES ciphers for the GCM. |
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*/ |
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abstract class AESCipher implements Cipher |
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{ |
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/** |
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* Mapping from key size in bits to AES cipher implementation class name. |
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* |
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* @internal |
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* |
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* @var array |
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*/ |
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const MAP_KEYSIZE_TO_CLS = array( |
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/* @formatter:off */ |
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128 => AES128Cipher::class, |
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192 => AES192Cipher::class, |
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256 => AES256Cipher::class |
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/* @formatter:on */ |
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); |
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/** |
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* Get the cipher method name recognized by OpenSSL. |
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* |
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* @return string |
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*/ |
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abstract protected function _cipherName(): string; |
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/** |
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* Get the key size in bytes. |
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* |
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* @return int |
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*/ |
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abstract protected function _keySize(): int; |
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/** |
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* Get AES cipher instance by key length. |
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* |
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* @param int $len Key length in bytes |
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* @throws \UnexpectedValueException |
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* @return self |
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*/ |
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public static function fromKeyLength(int $len): self |
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{ |
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$bits = $len << 3; |
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if (!array_key_exists($bits, self::MAP_KEYSIZE_TO_CLS)) { |
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1 |
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throw new \UnexpectedValueException( |
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1 |
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"No AES implementation for $bits-bit key size."); |
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} |
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$cls = self::MAP_KEYSIZE_TO_CLS[$bits]; |
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return new $cls(); |
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} |
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/** |
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* |
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* @see \Sop\GCM\Cipher\Cipher::encrypt() |
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* @throws \UnexpectedValueException If key size is incorrect |
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* @throws \RuntimeException For generic errors |
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* @return string |
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*/ |
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public function encrypt(string $data, string $key): string |
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{ |
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$key_size = $this->_keySize(); |
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if (strlen($key) != $key_size) { |
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3 |
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throw new \UnexpectedValueException( |
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3 |
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"Key size must be $key_size bytes."); |
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} |
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$result = openssl_encrypt($data, $this->_cipherName(), $key, |
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OPENSSL_RAW_DATA | OPENSSL_ZERO_PADDING); |
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if (false === $result) { |
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1 |
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throw new \RuntimeException( |
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1 |
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"openssl_encrypt() failed: " . self::_getLastOpenSSLError()); |
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} |
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return $result; |
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} |
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/** |
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* Get latest OpenSSL error message. |
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* |
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* @return string |
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*/ |
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protected static function _getLastOpenSSLError(): string |
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{ |
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$msg = ''; |
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1 |
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while (false !== ($err = openssl_error_string())) { |
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1 |
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$msg = $err; |
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} |
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1 |
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return $msg; |
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} |
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} |
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sop /
gcm
