3.11.3 Integrity

Ensuring that all devices have a consistent view of a user’s sigchain and that no extraneous devices have been added to it (by comparing fingerprints or relying on the ZTT and monitoring one’s own sigchain) also helps with integrity guarantees. Users can ensure communications haven’t been tampered with by checking that they are signed by devices belonging to the claimed author. However, as above, in some cases the evidence of compromise might be less conclusive: if the sender signs a message using a device’s signing key, and later revokes that device (for example, because the device was lost or compromised), the recipient has no way to tell if the message was signed before or after the revocation/compromise. The user interface may communicate this potential risk to the recipient so that they can confirm the integrity of any sensitive communications with the sender out-of-band, or ask them to resend the message with an up-to-date key.