Key Transparency

Key Transparency allows communicating parties to verify public keys used in end-to-end encryption.^[1] In many end-to-end encryption services, to initiate communication a user will reach out to a central server and request the public keys of the user with which they wish to communicate.^[2] If the central server is malicious or becomes compromised, a man-in-the-middle attack can be launched through the issuance of incorrect public keys. The communications can then be intercepted and manipulated.^[3] Additionally, legal pressure could be applied by surveillance agencies to manipulate public keys and read messages.^[2]

With Key Transparency, public keys are posted to a public log that can be universally audited.^[4] Communicating parties can verify public keys used are accurate.^[4]