65be6f2b96
`FirstMessageTimestamp` enables members of the community to determine if there are any messages they can fetch on the community channel(chat). `FirstMessageTimestamp` is advertised by admin for each community chat through `CommunityDescription`. It assumes admin is online frequently enough to capture the first channel message. For existing communities admin determines first message timestamp by finding oldest chat message in its local database. task: status-im/status-desktop#6731
protocol/encryption package
Hash ratchet encryption
encryptor.GenerateHashRatchetKey() generates a hash ratchet key and stores it in in the DB.
There, 2 new tables are created: hash_ratchet_encryption and hash_ratchet_encryption_cache.
Each hash ratchet key is uniquely identified by the (groupId, keyId) pair, where keyId is derived from a clock value.
protocol.BuildHashRatchetKeyExchangeMessage builds an 1-on-1 message containing the hash ratchet key, given it's ID.
protocol.BuildHashRatchetMessage builds a hash ratchet message with arbitrary payload, given groupId. It will use the latest hash ratchet key available. encryptor.encryptWithHR encrypts the payload using Hash Ratchet algorithms. Intermediate hashes are stored in hash_ratchet_encryption_cache table.
protocol.HandleMessage uses encryptor.decryptWithHR fn for decryption.