I built a cryptographic audit receipt for Claude Mythos (and any AI model) — here's how it works

A developer named Pulkit has built Aetherproof, an open-source Python library that generates cryptographic audit receipts for AI model outputs in a single function call. The tool creates Ed25519-signed receipts proving when specific findings were generated by Anthropic's Claude Mythos model, and can invisibly embed those receipts into text using Unicode Private Use Area codepoints. In testing, the library passed 187 tests with zero failures and detected all 128-byte flip attempts across 1,000 tamper probes.

Anthropic's Mythos model can autonomously find zero-day vulnerabilities. Their CVD disclosure process uses manual SHA-3-512 hash commitments to prove findings existed. I built something that automates that in one line of Python. One function call generates a 128-byte Ed25519-signed receipt that proves: python python import aetherproof receipt = aetherproof.for anthropic "Find vulnerabilities in this binary.", finding text, model="claude-mythos-preview" receipt.save "CVE-2026-001.receipt" print receipt.verify True Try it in 30 seconds pip install aetherproof python -c " import aetherproof r = aetherproof.for anthropic 'question', 'answer' print r.verify True print r.pretty " The unusual part — invisible Unicode watermarking Receipts embed invisibly into any text using Unicode Private Use Area codepoints U+E000–U+E0FF . AI output carries its own audit trail. Works in any language — Arabic, Chinese, Devanagari, Hebrew, Thai, Japanese all tested. signed output = aetherproof.embed ai response, receipt.to bytes Text looks identical. Receipt is inside. aetherproof.verify embedded signed output True Numbers 187 tests, 0 failures 128/128 byte flips all detected 1000/1000 tamper probes pass Cross-language: Python generates, Rust CLI verifies 15,446 receipts/sec Python · 5,472/sec Rust Why AGPL-3.0 Free for open source. Commercial use needs a license. This is the compliance layer under your AI stack — it should be open, auditable, and not vendor-locked. GitHub https://github.com/pulkit6732/aetherproof Built by Pulkit. Feedback welcome.