harmonia-utils-base-encoding

Base encoding/decoding utilities for the various encodings Nix uses.

Overview

This crate provides encoding and decoding for the base encodings used by Nix, including the special Nix base32 alphabet. It is a standalone crate that can be used by any project needing Nix-compatible encoding.

Contents

• base32 - Nix base32 encoding (special 32-character alphabet, LSB first, reversed)
• Base - Enum for selecting encoding format (Hex, NixBase32, Base64)
• decode_for_base / encode_for_base - Get encode/decode functions for a given base
• base64_len - Calculate base64 encoded length

Example API

// Nix base32 encoding
pub mod base32 {
    pub fn encode_string(input: &[u8]) -> String;
    pub fn decode_mut(input: &[u8], output: &mut [u8]) -> Result<usize, DecodePartial>;
}

// Base encoding selection
pub enum Base { Hex, NixBase32, Base64 }
pub fn decode_for_base(base: Base) -> impl Fn(&[u8], &mut [u8]) -> Result<usize, DecodePartial>;

Nix Base32

Nix uses a non-standard base32 encoding:

• Alphabet: 0123456789abcdfghijklmnpqrsvwxyz (no e, o, t, u)
• Bit order: Least significant first
• Output is reversed compared to standard base32

This matches the encoding used in Nix store paths.

Key Characteristics

• Pure functions, no I/O
• No dependencies on other harmonia crates
• Tested against known Nix outputs