alien-lm / README.md
Jaehee Kim
Recover text-only responses with token segmentation
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---
title: AlienLM
emoji: 🛸
colorFrom: purple
colorTo: green
sdk: gradio
sdk_version: 6.19.0
app_file: app.py
short_description: AlienLM privacy layer for black-box LLMs
python_version: "3.12"
startup_duration_timeout: 30m
---
# AlienLM Space
Interactive research demo for [AlienLM](https://github.com/KimJaehee0725/AlienLM),
using the public
[`dsba-lab/gemma2-9b-it-alienlm-full`](https://huggingface.co/dsba-lab/gemma2-9b-it-alienlm-full)
checkpoint.
The Space uses the official repository's token-ID translation rule and startup
compatibility checks. Its inference path matches the
[`SingleAlienTokenizer`](https://github.com/KimJaehee0725/AlienLM/blob/icml/training/axolotl/tokenizers/single_alien_tokenizer.py)
used for training:
1. Render the natural-language chat with the original Gemma 2 tokenizer, then
translate the rendered text into alien text.
2. Encode the alien text with the original tokenizer, matching the
`SingleAlienTokenizer` path used during training.
3. Decode generated token IDs with the unchanged original tokenizer, matching a
black-box server that returns text and no token metadata.
4. On the client side, invert the original tokenizer's decoded-piece lattice,
keep the minimum-token segmentations, and rank their alien-decoded natural
text locally. The server tokenizer is not modified.
The Space includes the alien tokenizer files required by the model. Access to
the gated `google/gemma-2-9b-it` tokenizer is supplied through the Space's
`HF_TOKEN` secret.
## Privacy scope
This hosted Space is an interactive pipeline demo: natural-language input first
reaches the Space backend, where translation and model inference run in the same
process. In the deployment described by the paper, the translator and bijection
remain on a trusted client so that only alienized text crosses the black-box LLM
API boundary. AlienLM is a research method, not a formal cryptographic privacy
guarantee.
The inverse segmentation step is necessarily heuristic when the server returns
only a fused string: multiple token-ID sequences can decode to the same text.
The demo uses minimum token count as a strong prior and resolves collisions
using only tokenizer-internal signals: alien-side canonicality, structural
validity, and the original tokenizer's BPE vocabulary rank. It does not use a
second language model. Special tokens intentionally removed by the server
cannot be reconstructed, but are not part of the visible response content.
The search budget is intentionally tuned for the Space's short demo responses;
long-form reconstruction is outside this demo's scope.
## Links
- [Paper](https://arxiv.org/abs/2601.22710)
- [Project page](https://kimjaehee0725.github.io/AlienLM/)
- [Official code](https://github.com/KimJaehee0725/AlienLM)
- [Model collection](https://huggingface.co/collections/dsba-lab/alienlm)