Verifiable Provenance

CRC answered “intact.” Provenance answers “which key.”

1.2 sealed a soul into an SPK1 packet with CRC-32 — integrity only. 1.3 made that story one command: uvx claude-fafm-sdk receipt. A stranger could prove the bytes weren’t mangled.

What CRC never claimed: which key sealed these bytes. That’s not a human identity, not a trust product, not encryption. It’s a key binding. 1.4 adds it as an optional layer on the same transport.

Signature covers the same raw payload CRC covers. Flag bit 0 = SIGNED. Trailer is a fixed 64-byte Ed25519 signature — no key_id, no embedded pubkey (later). Unsigned seals stay byte-identical to 1.2/1.3.

What's New

• [sign] extra → cryptography — Ed25519 only when you install it. Missing extra → clean “install claude-fafm-sdk[sign]” message, never a raw ImportError.
• Library — sign_packet / verify_packet / generate_keypair (top-level exports). PEM-only keys in 1.4-min.
• CLI — keygen (writes sign.pem at 0600 + sign.pub.pem), seal --sign --key, verify -k.
• Strict open — from_packet and CLI open refuse a signed packet (point at verify). merge_packet never CRC-opens a signed peer; pass public_key or reject.
• Receipt unchanged — uvx claude-fafm-sdk receipt still GREEN, still zero-crypto.

How to run it

Honesty bounds

• Provenance, never “trust.” A key signed these payload bytes — not a human identity, not a PKI, not “authenticated memory.”
• Strip-downgrade is possible — drop the 64-byte trailer and clear SIGNED → equivalent unsigned packet of the same payload. The flag is not signed. Demand verify when you need provenance.
• Old 1.2/1.3 readers reject full signed files (length-exact) — they do not silently CRC-open them.
• SPK1 ≠ FAFB — not project-binary signing, no FLAG_SIGNED interop with the FAFB format.
• Merge oracle untouched — transport only; CvRDT dual-impl remains the 1.1 story. Deletes still don’t converge (→ Forgettable Memory / 1.5).
• No encryption in this edition.

The Numbers

• v1.4.0 — production on PyPI (Verifiable Provenance)
• Optional Ed25519 — fixed 64-byte trailer, payload-aligned with CRC
• Zero-crypto base — receipt + seal/merge/open without [sign]
• PyPI: claude-fafm-sdk 1.4.0
• GitHub: v1.4.0 release

The arc

Mergeable → Sendable → Provable → Verifiable → Forgettable.

• 1.1 Mergeable Memory — souls join (CvRDT)
• 1.2 Sendable Memory — SPK1 + CRC travel
• 1.3 Provable Receipt — one-command stranger proof
• 1.4 Verifiable Provenance — which key sealed it
• 1.5 Forgettable Memory — tombstones (shipped — read the post)