What happens when you sign
Tap Sign, confirm with Face ID, done in about two seconds. Underneath, Mark does eight things — each optional to understand and all of them inspectable.
Signing
8 stepsWhen you tap Sign, Mark runs eight steps in sequence. Each one is a complete, true statement on its own — expand any row to see the mechanism underneath.
Sharing
Verification code — a short alphanumeric code. Send it via text, email, or chat. Codes expire.
Verification link — a direct URL that opens the result immediately. Same expiration.
Signed bundle file — the raw JSON proof artifact. Self-contained, independently verifiable, permanent.
Verifying
5 checksThe verifier checks five things, in order, and needs no account, no app, and no relationship with Mark.
If all five pass: VALID. If any check fails, the verifier names exactly which one and why.
Co-signing
Mark supports multi-party signing through SigningEnvelopes. Two modes, identical proof:
Document attached. The initiator uploads to encrypted S3. Co-signers preview before signing.
Hash only. Co-signers already have the document. The envelope contains only the hash.
The key hierarchy
Root key — your master identity key. Created once. Lives in secure hardware. This key is your identity.
Signing subkey — authorized by your root key, with a limited validity period. Used for daily signing. Cheap to rotate, safe to expire.
Lose your phone, and you revoke the subkey using your root key. Signatures made before the compromise stay valid. Your identity survives.