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What is a reversible function?

Please see co-stack/reversible for more information about reversibles.

About

This package is an extension to co-stack/reversible. It contains several reversibles for Encryption/Decryption and Signing/Verifying messages. All reversibles in this package are based on paragonie/halite, a "High-level cryptography interface powered by libsodium".

Examples

Simple hybrid encryption

Encode and send the message

$localPrivateKey = \ParagonIE\Halite\KeyFactory::loadEncryptionSecretKey('/path/to/local/private.key');
$foreignPublicKey = \ParagonIE\Halite\KeyFactory::loadEncryptionPublicKey('/path/to/foreign/key.pub');

$superSecretMessage = 'Foo bar baz! Beng? Baz baz. Bada boom. Multipass!';

$reversible = new \CoStack\ReversibleHalite\Operation\Encryption\AuthenticatedAsymmetricEncryption(
    $localPrivateKey->getRawKeyMaterial(),
    $foreignPublicKey->getRawKeyMaterial()
);

$encryptedMessage = $reversible->execute($superSecretMessage);

// Send the $encryptedMessage to the receiver. You can send this per HTTP or Telnet, it is securely encrypted with the
// receivers public key and authenticated by your private key.
send($encryptedMessage);

Receive and decrypt the message

$encryptedMessage = receive();

$localPrivateKey = \ParagonIE\Halite\KeyFactory::loadEncryptionSecretKey('/path/to/foreign/private.key');
$foreignPublicKey = \ParagonIE\Halite\KeyFactory::loadEncryptionPublicKey('/path/to/local/key.pub');

$reversible = new \CoStack\ReversibleHalite\Operation\Encryption\AuthenticatedAsymmetricEncryption(
    $localPrivateKey->getRawKeyMaterial(),
    $foreignPublicKey->getRawKeyMaterial()
);

try {
    $superSecretMessage = $reversible->reverse($encryptedMessage);
} catch (\CoStack\Reversible\Exception\DecryptionFailedException $exception) {
    echo 'The message was altered or was not sent by a trusted source!';
    exit(1);
}

Wait. The example says "hybrid encryption", but the code uses AuthenticatedAsymmetricEncryption? Yes, this is correct. Asymmetric encryption has some drawbacks, like the maximum length of the encrypted information and its very slow execution. To bypass these limitations, halite generates a shared secret key based on the encryption and decryption keys. Then, the shared secret key is used to encrypt the message with high performance.

In a pipe

The true power of co-stack/reversible lies in its portability and chaining of functions. You can compose a set of functions into a pipe, which can be executed and reversed like it would be a single reversible.

$signingPrivateKey = \ParagonIE\Halite\KeyFactory::loadEncryptionSecretKey('/path/to/local/private.key');
$encryptionPublicKey = \ParagonIE\Halite\KeyFactory::loadEncryptionPublicKey('/path/to/foreign/key.pub');

$pipe = new \CoStack\Reversible\Applicable\ReversiblePipe();
$pipe->enqueue(new \CoStack\ReversibleHalite\Operation\Encryption\SignedAsymmetricEncryption($signingPrivateKey, $encryptionPublicKey));
$pipe->enqueue(new \CoStack\Reversible\Operation\Compression\GzipCompression());
$pipe->enqueue(new \CoStack\Reversible\Operation\Encoding\UrlEncode());

$myValue = 'foo bar baz';

$secretEncodedEncryptedSigned = $pipe->execute($myValue);

// Transfer

$decryptionPrivateKey = \ParagonIE\Halite\KeyFactory::loadEncryptionSecretKey('/path/to/foreign/private.key');
$validationPublicKey = \ParagonIE\Halite\KeyFactory::loadEncryptionPublicKey('/path/to/local/key.pub');

$pipe = new \CoStack\Reversible\Applicable\ReversiblePipe();
$pipe->enqueue(new \CoStack\ReversibleHalite\Operation\Encryption\SignedAsymmetricEncryption($decryptionPrivateKey, $validationPublicKey));
$pipe->enqueue(new \CoStack\Reversible\Operation\Compression\GzipCompression());
$pipe->enqueue(new \CoStack\Reversible\Operation\Encoding\UrlEncode());

try {
    $myOriginalValue = $pipe->reverse($secretEncodedEncryptedSigned);
} catch (\Throwable $exception) {
    echo 'The message was altered or was not sent by a trusted source!';
    exit(1);
}
$myValue === $myOriginalValue; // true

co-stack / reversible-halite

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