README

This is a PHP 8+ implementation of Ascon v1.2, an authenticated cipher and hash function. It allows to encrypt and decrypt any kind of message. At kind be somewhat seen as the successor to AES encryption. Heavily inspired by the python implementation of Ascon by https://github.com/meichlseder/pyascon

About Ascon

Ascon is a family of authenticated encryption (AEAD) and hashing algorithms designed to be lightweight and easy to implement, even with added countermeasures against side-channel attacks. It was designed by a team of cryptographers from Graz University of Technology, Infineon Technologies, and Radboud University: Christoph Dobraunig, Maria Eichlseder, Florian Mendel, and Martin Schläffer.

Ascon has been selected as the standard for lightweight cryptography in the NIST Lightweight Cryptography competition (2019–2023) and as the primary choice for lightweight authenticated encryption in the final portfolio of the CAESAR competition (2014–2019).

Find more information, including the specification and more implementations here:

https://ascon.iaik.tugraz.at/

About me

I have made library for AES PHP/JS encryption already in the past. Bit juggling is somewhat cool, in a really nerdy way. I like the Ascon implementation and it at the time of writing, a PHP implementation was missing. So i made one. Would be cool if you leave a follow or spend some virtual coffee. s

Javascript/Typescript Implementation

Chances are high that you probably need a Javascript/Typescript (For your frontend) implementation too. I've made one here -> https://github.com/brainfoolong/js-ascon

Installation

# via composer
composer require brainfoolong/php-ascon

Usage

For more demos see in folder demo.

use Nullix\Ascon\Ascon;
// convenient usage (generating random nonce and hashing keys for you)
$key = "mypassword";
$message = ["this can be any data type 😎 文 or encoding", 123];
$associatedData = "Some data 😋 文 This data is not contained in the encrypt output but must be passed to both encrypt and decrypt.";
$encrypted = Ascon::encryptToHex($key, $message, $associatedData);
$decrypted = Ascon::decryptFromHex($key, $encrypted, $associatedData);

// raw usage of basic methods
// key must be 16 bytes or 20 bytes, depending on variant
$key = [0x90, 0x80, 0x70, 0x60, 0x50, 0x40, 0x30, 0x20, 0x10, 0xAA, 0x90, 0x90, 0x90, 0x90, 0xCC, 0xEF];
// nonce must be 16 bytes and should always be random bytes, you must use same nonce for encrypt and decrypt the same message
$nonce = random_bytes(16);
// this is the text you want to encrypt
$plaintext = "Hi, i am a secret message!";
// associated data is not being encrypted, but is taken into account in the ciphertext
// this means, you can only decrypt when you pass the exact same associated data to the decrypt function as well
// so you can make sure that associated data and plaintext is not manipulated for given encrypted message
// this is optional and can be an empty string
$associatedData = "Some data to pass to encryption and decryption - This data is not contained in the ciphertext output.";
$ciphertextByteArray = Ascon::encrypt($key, $nonce, $associatedData, $plaintext);
$plaintextDecrypted = Ascon::decrypt($key, $nonce, $associatedData, $ciphertextByteArray);

var_dump(Ascon::hash('Testmessage'));
var_dump(Ascon::mac($key, 'Testmessage'));

Performance and PHP limitations (No showstopper, but you should take notice)

Ascon requires 64bit unsigned integers. PHP does NOT have 64bit unsigned integers, it only have signed 64bit integers. So, by default we miss one bit for a full unsigned 64bit number (Because the 64th bit is used for the sign instead of the last number bit). Php internally translates a full used 64bit number to float, which is a mess and don't work because you loose data because of floating point precision limitation.

But no fear, in this implementation i have used 2x 32bit integers internally. This have some performance impact, because more operations need to be done to get the same result as with uint 64 bit. If you need top notch performance for a lot of encrypt/decrypt, i always recommend that you not use PHP for such jobs. Use the native C implementation, which is a lot faster. You can embed that with FFI as of PHP 8.2.

However, you are probably here because you need it to integrate it in your webservice application. For this cases, the performance should be fine.

See tests/performance.php for some tests with various message data size.

# no scientific tests, just executed on my local machine, results depend on your machine
# a "cycle" is one encryption and one decryption 

### 10 cycles with 64 byte message data and 256 byte associated data ###
Total Time: 0.07 seconds
Memory Usage: 2MB

### 10 cycles with 256 byte message data and 1024 byte associated data ###
Total Time: 0.21 seconds
Memory Usage: 2MB

### 10 cycles with 2048 byte message data and 4096 byte associated data ###
Total Time: 0.92 seconds
Memory Usage: 2MB

### 10 cycles with 8192 byte message data and 0 byte associated data ###
Total Time: 1.34 seconds
Memory Usage: 4MB

Implemented Algorithms

This is a simple reference implementation of Ascon v1.2 as submitted to the NIST LWC competition that includes

Authenticated encryption/decryption with the following 3 variants:
- Ascon-128
- Ascon-128a
- Ascon-80pq
Hashing algorithms including 4 hash function variants with fixed 256-bit (Hash) or variable (Xof) output lengths:
- Ascon-Hash
- Ascon-Hasha
- Ascon-Xof
- Ascon-Xofa
Message authentication codes including 5 MAC variants (from https://eprint.iacr.org/2021/1574, not part of the LWC proposal) with fixed 128-bit (Mac) or variable (Prf) output lengths, including a variant for short messages of up to 128 bits (PrfShort).
- Ascon-Mac
- Ascon-Maca
- Ascon-Prf
- Ascon-Prfa
- Ascon-PrfShort

brainfoolong / php-ascon

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