# Path Hasher - A PHP implementation of Nix’s NAR format

**URL:** https://discourse.nixos.org/t/path-hasher-a-php-implementation-of-nix-s-nar-format/71222
**Category:** Announcements
**Created:** [October 24, 2025, 2:57pm UTC](https://discourse.nixos.org/t/path-hasher-a-php-implementation-of-nix-s-nar-format/71222 "2025-10-24T14:57:03Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![drupol](https://discourse.nixos.org/user_avatar/discourse.nixos.org/drupol/32/9471_2.png) [@drupol](https://discourse.nixos.org/u/drupol)
#### Post date: [October 24, 2025, 2:57pm UTC](https://discourse.nixos.org/t/path-hasher-a-php-implementation-of-nix-s-nar-format/71222/1 "2025-10-24T14:57:03Z")

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Heya everyone,

I have just released [Path Hasher](https://github.com/loophp/path-hasher), a PHP library that deterministically serialises and hashes filesystem paths using the **NAR (Nix ARchive)** format introduced by Eelco Dolstra in his [PhD thesis](https://edolstra.github.io/pubs/phd-thesis.pdf).

### What it offers

- Serialise files, directories and symlinks into the canonical NAR format.
- Compute hashes in hex, SRI and Nix base32 encodings, matching the output of `nix hash path <path>`.
- Extract or reconstruct filesystem trees from NAR archives.

### Why I created it

1. To understand how the NAR format works and how it’s built.
2. To provide deterministic serialisation of paths/directories in PHP—without needing any external tooling.
3. To ease adoption of the NAR format in the PHP ecosystem (and specifically with Composer) — e.g., see [this Composer pull request comment](https://github.com/composer/composer/pull/12524#issuecomment-3443548262).
4. Because it was fun.

### Performances

```console
❯ nix hash path /home/pol/Code/drupol/nixpkgs/pkgs/by-name/
sha256-cAPagRB1zSY5EOcuX27fhyjzY4XmkMj3kvX7cQ8xd6I=

❯ php hash.php /home/pol/Code/drupol/nixpkgs/pkgs/by-name/
sha256-cAPagRB1zSY5EOcuX27fhyjzY4XmkMj3kvX7cQ8xd6I=⏎                                                                                                                                                                                                                                                                                                                                                                                                                                                  
 
❯ hyperfine "nix hash path /home/pol/Code/drupol/nixpkgs/pkgs/by-name/" --warmup 2
Benchmark 1: nix hash path /home/pol/Code/drupol/nixpkgs/pkgs/by-name/
  Time (mean ± σ): 354.2 ms ± 7.2 ms [User: 237.9 ms, System: 114.1 ms]
  Range (min … max): 346.4 ms … 371.6 ms 10 runs
 
❯ hyperfine "php hash.php /home/pol/Code/drupol/nixpkgs/pkgs/by-name/" --warmup 2
Benchmark 1: php hash.php /home/pol/Code/drupol/nixpkgs/pkgs/by-name/
  Time (mean ± σ): 431.1 ms ± 7.9 ms [User: 269.4 ms, System: 158.8 ms]
  Range (min … max): 423.7 ms … 449.9 ms 10 runs

```

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<div class="post-metadata">

### Author: ![fzakaria](https://discourse.nixos.org/user_avatar/discourse.nixos.org/fzakaria/32/2643_2.png) [@fzakaria](https://discourse.nixos.org/u/fzakaria)
#### Post date: [October 24, 2025, 8:31pm UTC](https://discourse.nixos.org/t/path-hasher-a-php-implementation-of-nix-s-nar-format/71222/2 "2025-10-24T20:31:34Z")

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You might find this PR i am working on of interest: [Add documentation for NAR spec in kaitai by fzakaria · Pull Request #14345 · NixOS/nix · GitHub](https://github.com/NixOS/nix/pull/14345)

(and [Make `nix nar [cat|ls]` lazy by fzakaria · Pull Request #14273 · NixOS/nix · GitHub](https://github.com/NixOS/nix/pull/14273) for comparing efficiency)