php-keccak256

A lightweight PHP extension that provides Ethereum-compatible Keccak-256 hashing (padding suffix 0x01) with minimal overhead.
This is not the NIST SHA3-256 (0x06) variant. Use hash('sha3-256', …) for standard SHA3-256.

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Features

• Keccak-256 only (Ethereum style, 0x01 padding)
• Raw or hex output: 32-byte binary blob or 64-character hex string
• Blazing fast: C wrapper outperforms pure-PHP implementations by ~17×

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Standards

Function	Padding	Purpose
keccak_hash() (this extension)	0x01	Ethereum, smart contracts, dApps
hash('sha3-256', …) (PHP built-in)	0x06	NIST SHA3-256 standard

Installation

Prerequisites

• PHP 8.1 or later
• PHP development headers and tools (php-dev, phpize, autoconf, make, gcc)

On Debian/Ubuntu:

sudo apt-get update
sudo apt-get install -y php-dev autoconf make gcc

Build & Install

1. Clone the repo:

   git clone https://github.com/RandomCoderTinker/php-keccak256.git
   cd php-keccak256

2. Prepare the build:

   phpize
   ./configure

3. Compile and install:

   make
   sudo make install

4. Enable the extension by adding to your php.ini:

   extension=keccak.so

5. Restart your web server or PHP-FPM:

   sudo service apache2 restart
   # or
   sudo service php8.x-fpm restart

Usage

<?php
$data = "hello world";

// Hexadecimal output (default)
$hex = keccak_hash($data);
echo $hex; // e.g. d4ee...a3f

// Raw binary output
$raw = keccak_hash($data, true);
echo bin2hex($raw); // same hex representation

Performance Comparison

Implementation	Hex Output	Raw Output
C extension (keccak_hash)	3.119 ms	2.902 ms
KornRunner PHP (Keccak::hash)	52.729 ms	50.877 ms

Benchmarked over 100 iterations on identical hardware. The C extension delivers a ~17× speedup over the pure-PHP KornRunner package.

Why Keccak-256 Only?

Many applications—especially blockchain clients, Ethereum tooling, and cryptographic protocols—rely exclusively on the 256-bit Keccak (SHA-3) digest:

• Standardization: Ethereum and many smart-contract platforms specify Keccak-256 as the sole hash function.
• Simplicity: If you don’t need SHA-3-224, SHA-3-384, SHA-3-512, or other ciphers, a focused extension lowers complexity, binary size, and attack surface.
• Performance: A minimal implementation optimizes for one output size; there’s no overhead handling multiple rates or capacities.

By offering just Keccak-256, this extension provides a drop-in, high-performance hash function tailored to the vast ecosystem of applications that only require the 256-bit variant.

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Built with ❤️ using PHP 8.1+