Keep It Private: Unsupervised Privatization of Online Text (2405.10260v1)

Abstract: Authorship obfuscation techniques hold the promise of helping people protect their privacy in online communications by automatically rewriting text to hide the identity of the original author. However, obfuscation has been evaluated in narrow settings in the NLP literature and has primarily been addressed with superficial edit operations that can lead to unnatural outputs. In this work, we introduce an automatic text privatization framework that fine-tunes a LLM via reinforcement learning to produce rewrites that balance soundness, sense, and privacy. We evaluate it extensively on a large-scale test set of English Reddit posts by 68k authors composed of short-medium length texts. We study how the performance changes among evaluative conditions including authorial profile length and authorship detection strategy. Our method maintains high text quality according to both automated metrics and human evaluation, and successfully evades several automated authorship attacks.

Keeping It Private: Authorship Obfuscation with LLMs

Introduction

So, you're browsing Reddit, maybe posting some insightful comments, and all of a sudden, you start to get a little paranoid—what if someone figures out who you are? This isn't just a worry for whistleblowers or people with a high online presence; it can affect anyone. Authorship obfuscation is all about using tech to rewrite your text in a way that keeps your identity hidden. This paper introduces us to a new framework called "Keep it Private" that uses LLMs to do exactly that.

The Need for Authorship Obfuscation

Online privacy is critical. Even if you're using a pseudonym, stylistic markers in your writing can still give away your identity. Think Sherlock Holmes, but instead of solving crimes, he's just piecing together your internet history. Previous attempts at authorship obfuscation have been kind of basic—you know, rule-based systems and such. These approaches often end up making your text sound weird. This new method aims to keep things natural while providing privacy.

How It Works

Reinforcement Learning for Text Privatization

At the core of this new method is reinforcement learning (RL). The idea here is to fine-tune pre-trained LLMs to generate text that balances between keeping your identity private and making sense. Here's a simplified look at the process:

• Input Text: Your original post or comment.
• Output Text: A modified version that hides your identity but retains the meaning.
• Training Mechanism: The system uses Self-Critical Sequence Training (SCST), which is a kind of optimization technique. Essentially, the model tries multiple rewrites and picks the best one based on a reward system.

Reward Components

These rewards cover three main areas:

1. Privacy: Measures how well the output text hides your identity.
2. Meaning Preservation: Ensures that your original message is not lost.
3. Soundness: Keeps the output text grammatically acceptable and natural-sounding.

Results

So, does it actually work? The researchers tested this on a large set of Reddit posts, involving 68,000 authors. Here's a snapshot of what they found:

• Privacy: The new method managed to fool various authorship attribution and verification models significantly well, scoring better than previous methods like rule-based systems and round-trip machine translation.
• Meaning Preservation: The output text maintained high similarity with the original text in terms of meaning. The scores were high across automated metrics and human evaluations.
• Soundness: The generated text was also well-formed and coherent according to both automatic judgment and human evaluators.

Implications

This new framework is practical and highly relevant for anyone concerned about maintaining online privacy. For researchers, it opens up new avenues to explore how advanced LLMs can be fine-tuned for specific tasks like this. On the practical side, it could be integrated into online platforms to help users remain anonymous while sharing content.

Future Developments

Looking ahead, this research can be expanded to:

• Different Languages: Applying the method to languages other than English.
• Diverse Text Lengths and Types: Testing on longer articles or different forms of writing.
• Robustness Against Various Adversaries: Improving the model to counter a broad range of authorship detection techniques.

Conclusion

In a nutshell, this "Keep it Private" framework is a promising step forward in authorship obfuscation. It's like having a smart, undercover writer tweaking your content to keep your secrets safe. Whether you're a journalist, activist, or just someone wanting to keep a low profile online, this new approach offers a practical solution that keeps your words—yours.

And that's a wrap! This new method may not make you invisible, but it certainly makes you a lot harder to find. Happy posting!