/** * Unseal a (file handle) * * @param ReadOnlyFile $input * @param MutableFile $output * @param EncryptionSecretKey $secretkey * * @return bool * @throws CryptoException\CannotPerformOperation * @throws CryptoException\InvalidMessage */ protected static function unsealData(ReadOnlyFile $input, MutableFile $output, EncryptionSecretKey $secretkey) : bool { $secret_key = $secretkey->getRawKeyMaterial(); $public_key = \Sodium\crypto_box_publickey_from_secretkey($secret_key); if ($input->getSize() < Halite::VERSION_TAG_LEN) { throw new CryptoException\InvalidMessage("File is too small to have been encrypted by Halite."); } // Parse the header, ensuring we get 4 bytes $header = $input->readBytes(Halite::VERSION_TAG_LEN); // Load the config $config = self::getConfig($header, 'seal'); if ($input->getSize() < $config->SHORTEST_CIPHERTEXT_LENGTH) { throw new CryptoException\InvalidMessage("File is too small to have been encrypted by Halite."); } // Let's grab the public key and salt $eph_public = $input->readBytes($config->PUBLICKEY_BYTES); $hkdfsalt = $input->readBytes($config->HKDF_SALT_LEN); $nonce = \Sodium\crypto_generichash($eph_public . $public_key, '', \Sodium\CRYPTO_STREAM_NONCEBYTES); $ephemeral = new EncryptionPublicKey($eph_public); $key = AsymmetricCrypto::getSharedSecret($secretkey, $ephemeral, true); list($encKey, $authKey) = self::splitKeys($key, $hkdfsalt, $config); // We no longer need the original key after we split it unset($key); if ($config->USE_BLAKE2B) { $mac = \Sodium\crypto_generichash_init($authKey); \Sodium\crypto_generichash_update($mac, $header); \Sodium\crypto_generichash_update($mac, $eph_public); \Sodium\crypto_generichash_update($mac, $hkdfsalt); $old_macs = self::streamVerify($input, '' . $mac, $config); } else { $mac = \hash_init('sha256', HASH_HMAC, $authKey); \hash_update($mac, $header); \hash_update($mac, $eph_public); \hash_update($mac, $hkdfsalt); // This will throw an exception if it fails. $old_macs = self::streamVerify($input, \hash_copy($mac), $config); } $ret = self::streamDecrypt($input, $output, new EncryptionKey($encKey), $nonce, $mac, $config, $old_macs); unset($encKey); unset($authKey); unset($nonce); unset($mac); unset($config); unset($old_macs); return $ret; }
/** * Unseal the contents of a file. * * @param ReadOnlyFile $input * @param MutableFile $output * @param EncryptionSecretKey $secretKey * @return bool * @throws CannotPerformOperation * @throws InvalidMessage */ protected static function unsealData(ReadOnlyFile $input, MutableFile $output, EncryptionSecretKey $secretKey) : bool { $publicKey = $secretKey->derivePublicKey(); // Is the file at least as long as a header? if ($input->getSize() < Halite::VERSION_TAG_LEN) { throw new InvalidMessage("Input file is too small to have been encrypted by Halite."); } // Parse the header, ensuring we get 4 bytes $header = $input->readBytes(Halite::VERSION_TAG_LEN); // Load the config $config = self::getConfig($header, 'seal'); if ($input->getSize() < $config->SHORTEST_CIPHERTEXT_LENGTH) { throw new InvalidMessage("Input file is too small to have been encrypted by Halite."); } // Let's grab the public key and salt $ephPublic = $input->readBytes($config->PUBLICKEY_BYTES); $hkdfSalt = $input->readBytes($config->HKDF_SALT_LEN); // Generate the same nonce, as per sealData() $nonce = \Sodium\crypto_generichash($ephPublic . $publicKey->getRawKeyMaterial(), '', \Sodium\CRYPTO_STREAM_NONCEBYTES); // Create a key object out of the public key: $ephemeral = new EncryptionPublicKey(new HiddenString($ephPublic)); $key = AsymmetricCrypto::getSharedSecret($secretKey, $ephemeral, true); unset($ephemeral); list($encKey, $authKey) = self::splitKeys($key, $hkdfSalt, $config); // We no longer need the original key after we split it unset($key); $mac = \Sodium\crypto_generichash_init($authKey); \Sodium\crypto_generichash_update($mac, $header); \Sodium\crypto_generichash_update($mac, $ephPublic); \Sodium\crypto_generichash_update($mac, $hkdfSalt); $oldMACs = self::streamVerify($input, Util::safeStrcpy($mac), $config); // We no longer need this: \Sodium\memzero($hkdfSalt); $ret = self::streamDecrypt($input, $output, new EncryptionKey(new HiddenString($encKey)), $nonce, $mac, $config, $oldMACs); unset($encKey); unset($authKey); unset($nonce); unset($mac); unset($config); unset($oldMACs); return $ret; }
/** * Set up our key pair * * @param EncryptionSecretKey $secret */ protected function setupKeyPair(EncryptionSecretKey $secret) { $this->secretKey = $secret; $this->publicKey = $this->secretKey->derivePublicKey(); }
/** * Decrypt a sealed message with our private key * * @param string $ciphertext Encrypted message * @param EncryptionSecretKey $privateKey * @param mixed $encoding Which encoding scheme to use? * @return HiddenString * @throws InvalidKey * @throws InvalidMessage */ public static function unseal(string $ciphertext, EncryptionSecretKey $privateKey, $encoding = Halite::ENCODE_BASE64URLSAFE) : HiddenString { $decoder = Halite::chooseEncoder($encoding, true); if ($decoder) { // We were given hex data: try { $ciphertext = $decoder($ciphertext); } catch (\RangeException $ex) { throw new InvalidMessage('Invalid character encoding'); } } // Get a box keypair (needed by crypto_box_seal_open) $secret_key = $privateKey->getRawKeyMaterial(); $public_key = \Sodium\crypto_box_publickey_from_secretkey($secret_key); $key_pair = \Sodium\crypto_box_keypair_from_secretkey_and_publickey($secret_key, $public_key); // Wipe these immediately: \Sodium\memzero($secret_key); \Sodium\memzero($public_key); // Now let's open that sealed box $message = \Sodium\crypto_box_seal_open($ciphertext, $key_pair); // Always memzero after retrieving a value \Sodium\memzero($key_pair); if ($message === false) { throw new InvalidKey('Incorrect secret key for this sealed message'); } // We have our encrypted message here return new HiddenString($message); }