Follow-up on the Keycard Shell OpenPGP work: The SIGN_MESSAGE crypto/protocol path is now proven end-to-end on physical hardware. Flashed the beta5 firmware, generated a fresh signing request for the exact 74-byte Thurin statement, reviewed it on the Shell, signed with the Keycard, recovered the detached OpenPGP signature from the response QR, and verified it independently with GnuPG: gpg: Good signature from "Keycard Test " The resulting signature is a real OpenPGP v4 canonical-text signature: • type 0x01 • ECDSA / secp256k1 • SHA-256 • correct issuer fingerprint • correct signature creation time • exact statement bytes preserved with no trailing newline So the hardware signing path works. Physical testing also caught two UX issues: • SIGN_MESSAGE review was split across separate review steps • signing authorization used a normal press instead of an explicit hold Both are now fixed in the PR branch. SIGN_MESSAGE is now one combined trusted-review document: message → signature time → fingerprint → HOLD TO SIGN CREATE_IDENTITY now uses the same explicit hold-to-confirm authorization. Commit: 636d94f — openpgp: fix trusted review flow Then I updated the Thurin integration to the current stack: • @thurinlabs/thurin 0.13.8 • @thurinlabs/identity-kit 2.2.1 The good news: current Thurin supports exactly the detached-signature format the Shell produces. The verifier also caught one more OpenPGP interoperability issue: the certificate generated by CREATE_IDENTITY did not advertise Key Flags in its UID self-certification. identity-kit correctly rejected it as a signing key. Fixed that on the Shell side by adding the hashed OpenPGP Key Flags subpacket: 0x03 = certify + sign SIGN_MESSAGE itself stays unchanged. Commit: 635a8a2 — openpgp: advertise signing key flags Release firmware builds cleanly and the signing/certification paths remain separated. Now waiting for the next firmware build so I can do the final physical regression: CREATE_IDENTITY → confirm key flags → SIGN_MESSAGE → identity-kit verified: true → Thurin Sepolia attestation This ended up being a really useful integration pass — the hardware crypto works, the UX got tightened, and the current Thurin verifier caught a certificate metadata issue before the first on-chain claim.

Keycard Shell OpenPGP current status: SIGN_MESSAGE is now implemented and pushed for review. Shell can produce hardware-backed detached OpenPGP signatures with trusted review before signing. Added proper OpenPGP canonical-text signing (type 0x01): • LF → CRLF canonicalization • existing CRLF preserved • trailing newline semantics preserved • bare CR rejected • message length bounded to 104 bytes so the full statement remains reviewable on-device Trusted review now shows: • the exact message • signature creation time in UTC • the OpenPGP fingerprint The fingerprint is reconstructed from the Shell-owned key + key creation time. The host never supplies the fingerprint or derivation path. Also verified that CREATE_IDENTITY stayed wire-compatible. Software regressions now cover protocol round trips, malformed requests, timestamp ordering, 104/105-byte boundaries, newline canonicalization, trailing data rejection, and host-generated CBOR. Release firmware builds cleanly. Added host-side tooling for SIGN_MESSAGE too: • generate signing request QR • recover detached OpenPGP .sig • validate packet structure The first Thurin statement is 74 bytes and already satisfies the byte-exact requirements: lowercase Ethereum address, no trailing newline. Commit 0bb0442 — “openpgp: add message signing” — is pushed to the PR #227 branch. Next step is review + a fresh demo firmware build, then: physical Shell signing → recover .sig → GPG verify → first Thurin Sepolia claim. Good stopping point for today.