php_mt_seed_rs

A GPU-accelerated reimplementation of openwall's php_mt_seed (PHP 7.1.0+ only).
It searches for MT19937 seeds that produce given PHP mt_rand() outputs using a WebGPU (wgpu) compute shader.

8 times faster than the previous state of the art ! The numbers might vary depending on your configuration, but the ratio should stay more or less the same in most cases.

License: MIT OR Apache-2.0

Features

• Runs the search on the GPU via wgpu/WGSL for large, parallel throughput.
• Supports multiple mt_rand() outputs and optional ranges per output.
• Prints adapter info and progress while running.

Requirements

• Rust toolchain (stable).
• A system GPU with compute-shader support and working wgpu backend (Vulkan/Metal/D3D12 as appropriate).

Build

Build in release mode for best performance:

cargo build --release

Run

Usage pattern:

php_mt_seed_rs VALUE_OR_MATCH_MIN [MATCH_MAX [RANGE_MIN RANGE_MAX]] ...

• You may provide up to 8 matches (one match is match_min, match_max, range_min, range_max).
• Default range is 0..0x7fffffff when omitted.

Examples:

• Single value:

$ cargo run --release -- 1178568022
    Finished `release` profile [optimized] target(s) in 0.05s
     Running `target/release/php_mt_seed 1178568022`
Running on Adapter: AdapterInfo {
    name: "NVIDIA GeForce GTX 1660 Ti",
    vendor: 4318,
    device: 8593,
    device_type: DiscreteGpu,
    driver: "NVIDIA",
    driver_info: "575.64.05",
    backend: Vulkan,
}
seed = 0x0 = 0 (PHP 7.1.0+)
seed = 0xab2bbe62 = 2871770722 (PHP 7.1.0+)
seed = 0xec3f338f = 3963564943 (PHP 7.1.0+)
seed = 0x6784fafb = 1736768251 (PHP 7.1.0+)
progress: 256 / 256
$ cat > mt_rand.php <<EOF # let's check !
<?php
mt_srand(0);
echo mt_rand() . "\n";
EOF
$ php mt_rand.php # this outputs the correct number
1178568022

• Multiple values

$ cargo r --release -- 0 0 0 0 0 0 0 0 1457 1457 1000 10000 5452 5452 1000 10000 4474 4474 1000 10000
    Finished `release` profile [optimized] target(s) in 0.08s
     Running `target/release/php_mt_seed 0 0 0 0 0 0 0 0 1457 1457 1000 10000 5452 5452 1000 10000 4474 4474 1000 10000`
Running on Adapter: AdapterInfo {
    name: "NVIDIA GeForce GTX 1660 Ti",
    vendor: 4318,
    device: 8593,
    device_type: DiscreteGpu,
    driver: "NVIDIA",
    driver_info: "575.64.05",
    backend: Vulkan,
}
seed = 0x67932 = 424242 (PHP 7.1.0+)
progress: 256 / 256
$ cat > mt_rand.php <<EOF # let's check !
<?php
mt_srand(424242);
mt_rand();
mt_rand();
echo mt_rand(1000, 10000) . "\n";
echo mt_rand(1000, 10000) . "\n";
echo mt_rand(1000, 10000) . "\n";
EOF
$ php mt_rand.php # this outputs the correct numbers
1457
5452
4474

Tests

Unit/integration tests call the GPU prepare/execute code and therefore require a working GPU/wgpu environment. They may fail in environments without a compatible GPU or drivers.

To run tests:

cargo test

Troubleshooting

• "ERROR: there were many more results than what the GPU could transfer to the CPU" — too many matches; consider using openwall's original php_mt_seed tool for large result sets.

Contributing

Contributions and bug reports are welcome — open an issue or PR.

Thanks

• https://github.com/dcrewi/rust-mersenne-twister
• openwall php_mt_seed: https://github.com/openwall/php_mt_seed (docs)