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<?php namespace Limoncello\Crypt\Package; |
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/** |
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* Copyright 2015-2017 [email protected] |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0 |
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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*/ |
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use Limoncello\Contracts\Settings\SettingsInterface; |
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/** |
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* @package Limoncello\Crypt |
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*/ |
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class SymmetricCryptSettings implements SettingsInterface |
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{ |
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/** Default crypt method */ |
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const DEFAULT_METHOD = 'aes-256-ctr'; |
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/** Default Initialization Vector (IV) */ |
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const DEFAULT_IV = ''; |
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/** |
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* Encryption method to be used. For a list of available methods on your machine see openssl_get_cipher_methods(). |
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* |
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* @see http://php.net/manual/en/function.openssl-get-cipher-methods.php |
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*/ |
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const KEY_METHOD = 0; |
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/** Settings key */ |
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const KEY_PASSWORD = self::KEY_METHOD + 1; |
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/** Settings key */ |
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const KEY_IV = self::KEY_PASSWORD + 1; |
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/** |
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* @see http://php.net/manual/en/function.openssl-encrypt.php OPENSSL_ZERO_PADDING |
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* |
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* From @link http://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38a.pdf |
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* Appendix A: Padding |
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* ~~~~~~~~~~~~~~~~~~~ |
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* For the ECB, CBC, and CFB modes, the plaintext must be a sequence of one or more complete |
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* data blocks (or, for CFB mode, data segments). In other words, for these three modes, the total |
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* number of bits in the plaintext must be a positive multiple of the block (or segment) size. |
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* If the data string to be encrypted does not initially satisfy this property, then the formatting of the |
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* plaintext must entail an increase in the number of bits. A common way to achieve the necessary |
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* increase is to append some extra bits, called padding, to the trailing end of the data string as the |
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* last step in the formatting of the plaintext. An example of a padding method is to append a |
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* single ‘1’ bit to the data string and then to pad the resulting string by as few ‘0’ bits, possibly |
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* none, as are necessary to complete the final block (segment). Other methods may be used; in |
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* general, the formatting of the plaintext is outside the scope of this recommendation. |
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* For the above padding method, the padding bits can be removed unambiguously, provided the |
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* receiver can determine that the message is indeed padded. One way to ensure that the receiver |
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* does not mistakenly remove bits from an unpadded message is to require the sender to pad every |
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* message, including messages in which the final block (segment) is already complete. For such |
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* messages, an entire block (segment) of padding is appended. Alternatively, such messages can |
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* be sent without padding if, for every message, the existence of padding can be reliably inferred, |
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* e.g., from a message length indicator. |
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*/ |
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const KEY_USE_ZERO_PADDING = self::KEY_IV + 1; |
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// Authenticated Encryption with Associated Data specific keys (since PHP 7.1) |
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// @link http://php.net/manual/en/function.openssl-encrypt.php |
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/** Settings key */ |
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const KEY_USE_AUTHENTICATION = self::KEY_USE_ZERO_PADDING + 1; |
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/** Settings key */ |
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const KEY_TAG_LENGTH = self::KEY_USE_AUTHENTICATION + 1; |
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/** Settings key */ |
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const KEY_LAST = self::KEY_TAG_LENGTH; |
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/** |
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* @inheritdoc |
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*/ |
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final public function get(): array |
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{ |
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$defaults = $this->getSettings(); |
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$password = $defaults[static::KEY_PASSWORD] ?? null; |
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assert(empty($password) === false, "Password cannot be empty."); |
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return $defaults; |
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} |
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/** |
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* @return array |
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*/ |
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protected function getSettings(): array |
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{ |
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return [ |
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static::KEY_METHOD => static::DEFAULT_METHOD, |
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static::KEY_IV => static::DEFAULT_IV, |
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static::KEY_USE_ZERO_PADDING => false, |
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static::KEY_USE_AUTHENTICATION => false, |
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static::KEY_TAG_LENGTH => 16, |
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]; |
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} |
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} |
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