5 Key Sync | Trust Sync | Contact Sync | Task Sync
11 ## Forming a Device Group with Key Sync
15 A Sender is the Person sending a message. In case of M2M it is the Operating
16 Entity of the Device sending.
20 A Device is an entitiy, which is sending representative of a Sender.
24 A Device is in state Sole when it is not member of a Device group and when it
25 is not part of a Negotiation.
29 A Device is in state Grouped when it is member of a Device group and when it is
30 not part of a Negotiation.
32 ## Negotiation as a Transaction
36 A TID (transaction ID) is a UUID version 4 variant 1.
40 The Challenge is identified by a TID. The Challenge is being set by each Beacon
41 and must be repeated in a corresponding Negotiation Request. The Challenge has
44 1. The Challenge makes it possible to filter out own Beacons
45 1. The Challenge makes it necessary to be able to read the communication
46 channel (usually an Inbox), otherwise Beacons cannot be answered
50 A Negotiation is a Transaction identified by a TID. The Negotiation's TID is
51 the XOR of the two Challenge TIDs of the two devices, respectively.
57 The key with which the Sender of the message is signing. In case of trusted
58 messages this is signalled within the encrypted message. This is signalled by
59 by opt_field pEp-sender-sign, which is not reflected to the outer message.
61 Transports can opt to use HMAC or OMAC instead of digital signatures.
65 Keys with which others and not the Sender are signing a message.
69 A Sender Group Key is a Sender's signing key, which is used to update the
70 Device Group information. If it is reset the Device Groups breaks.