Maybe messages should include a coarse timestamp to prevent replay of old messages by some adversary.
Someone could resend a month old "yes" with your valid signature to a question someone asks now.
Also it might be beneficial to include sequence numbers or message IDs and for example echo the last 4 ids in following messages so recipients can detect holes. - The chat could insert some placeholder to notify recipients of missing previous messages.
Someone could resend a month old "yes" with your valid signature to a question someone asks now.
Also it might be beneficial to include sequence numbers or message IDs and for example echo the last 4 ids in following messages so recipients can detect holes. - The chat could insert some placeholder to notify recipients of missing previous messages.