fash

Obfuscate file and folder names without tampering their content. Fash recursively hashes names using a configurable algorithm, stores an encrypted mapping so you can restore them later, and leaves file contents completely untouched.

Why

You have a directory of sensitive documents, project files, or media and you want to share or store them without revealing the original naming structure. Fash turns every file and folder name into a hash digest while preserving the directory tree and all file contents.

Installation

npm install -g @udlearn/fash

Requires Node.js >= 22.

Quick Start

# Navigate to the directory you want to obfuscate
cd my-project

# Initialize fash (creates a .fash/ config directory)
fash init

# Hash all file and folder names (you will be prompted for a secret)
fash commit

# Restore original names when needed
fash undo

Commands

fash init

Initialize fash in the current directory. Creates a .fash/ directory with default configuration.

fash init
fash init --algorithm sha1 --exclude "*.log" "node_modules"

Option	Description	Default
-a, --algorithm <alg>	Hash algorithm (md5, sha1, sha256)	sha256
-e, --exclude <patterns...>	Glob patterns to skip	none

fash config

View or update configuration. Run without options to print current settings.

fash config
fash config --algorithm md5
fash config --exclude "*.log" "*.tmp" "dist"

fash commit

Hash all file and folder names and save an AES-256-CBC encrypted mapping. You will be prompted for a secret password -- this is required to decrypt the mapping later.

fash commit
fash commit --force   # overwrite an existing mapping

fash show

Inspect the current mapping (requires your secret to decrypt).

fash show              # show all items
fash show --files      # files only
fash show --directories # directories only
fash show --config     # print configuration

fash undo

Restore all original file and folder names from the encrypted mapping.

fash undo

How It Works

1. init creates a .fash/ directory with config.json and an empty log.jsonl.
2. commit walks the directory tree, computes a hash for every file and folder name, builds a full mapping, encrypts it with your secret (AES-256-CBC), saves it as map.encrypted, then renames everything on disk.
3. undo decrypts the mapping and renames everything back to the original names, working from the deepest paths upward.

The .fash/ directory contains:

File	Purpose
config.json	Algorithm and exclude patterns
log.jsonl	Append-only action log (JSON Lines)
map.encrypted	Encrypted original-to-hashed name mapping

Tip: Add .fash/ to your .gitignore -- the encrypted mapping and log are local state.

Security

• Mappings are encrypted with AES-256-CBC using a key derived from your secret.
• Hash names use the full digest length, making the original names unguessable.
• The secret is never stored on disk. If you lose it, the mapping cannot be decrypted.
• Exclude patterns let you skip files that should remain untouched.

License

MIT