Ucom.ch pEp Foundation Modern users of messaging systems usually have multiple devices, and often desire to send and receive encrypted messages on some or all of their devices. Using encryption on multiple devices often results in situations where messages cannot be decrypted on the device used to read the message due to a missing private key. This document specifies a protocol for secure peer-to-peer synchronization of private keys across devices belonging to the same user (pEp Key Synchronization Protocol). The pretty Easy privacy (pEp) protocols describe a set of conventions for the automation of operations traditionally seen as barriers to the use and deployment of secure end-to-end interpersonal messaging. These include, but are not limited to, key management, key discovery, and private key handling.