Signature tamper playground

Watch a cryptographic signature protect an agent-to-agent coordination manifest in real time. No account, no setup — everything below runs in your browser.

Fetching a live signed manifest from coproduct-a2a.fly.dev…

✓ Signature verified. This manifest was signed by the server's public key (from its Agent Card) and every byte is accounted for.

✗ Tampering detected. One byte was flipped in hydrate_log_rev; the ed25519 signature no longer verifies. If this manifest arrived over the wire, your agent would reject it.

Manifest fields

manifest_version: —
hydrate_log_rev: —
capability_envelope: —
provenance_trail[0]: —
cohort_witnesses: —
signature (truncated): —

Flips one integer; keeps the original signature; re-runs verification locally.

JCS-canonical payload diff

Left: the canonical bytes that were signed. Right: your tampered bytes. The highlighted span is the single change.

Original (verifies)

Tampered (fails)

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Powered by the coproduct.provable-coordination.v1 extension of A2A v1.0. The same verification runs in every language SDK (Python, Rust, TypeScript).