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Blog
Field notes
Notes on evidence that anyone can check.
How Trustvice signs receipts, how to verify them without us, and where their limits are. Written by the people who build it, checked against the documentation.
Two correct RFC 8785 implementations can still disagree on key order, big numbers and unpaired surrogates. We walk through each edge case in JavaScript and Python, what our canonicalizers do, and how shared test vectors catch drift.
What "automatic recording of events" asks of an agentic system, which fields make a log traceable, why self-written logs are weak evidence, how to reconcile retention with erasure, and where signed receipts help and where they do not.
A signed receipt is a precise, narrow statement. This is a careful account of the three things a valid Trustvice receipt establishes, the many things it does not, what you are still trusting us for, and how to present receipts so nobody overstates them.
Trustvice receipts are built on SHA-256 hashes and metadata, not on your documents, prompts or response bodies. This is the privacy design behind that choice, what it protects, and the places where it does not protect you on its own.
A worked example that builds a dependency-free receipt verifier with WebCrypto, checks it against a signed test vector, proves it rejects tampered receipts, and then ports the same procedure to Python and the shell.
A field-by-field tour of the Trustvice receipt envelope, why we sign an RFC 8785 canonical form instead of the bytes on the wire, how key IDs are derived from the keys themselves, and what the published key set promises.
Engineering
Receipts
Cryptography
6 min read
Topics
Every post is tagged with the subjects it covers.
Engineering
Cryptography
Testing
Compliance
AI agents
Receipts
Security
Evidence
Privacy
Design
Verification
Tutorial
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Live demo
Verify a receipt yourself
Paste any Trustvice receipt into the verifier. It checks the signature in your browser against our published keys, with no account needed.
Field notes