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.