The Signal messaging protocol uses two kinds of ratcheting to update the keys used to protect messages: Diffie-- Hellman ratcheting is used when the next message is sent in the opposite direction from the previous message; symmetric ratcheting with a hash function is used when the next message is sent in the same direction. Assume a powerful adversary who can capture and delay messages and has the ability to compromise devices later. 1. How does the ratcheting in Signal improve the security of messages against this adversary, in comparison to the security of: o email messages encrypted with PGP; o messages sent as application data in a TLS 1.3 session. 2. If several messages are sent in the same direction in the Signal protocol, how does their security compare to the security of messages sent successively in opposite directions?

The Signal messaging protocol uses two kinds of ratcheting to update the keys used to protect messages: Diffie-- Hellman ratcheting is used when the next message is sent in the opposite direction from the previous message; symmetric ratcheting with a hash function is used when the next message is sent in the same direction. Assume a powerful adversary who can capture and delay messages and has the ability to compromise devices later. 1. How does the ratcheting in Signal improve the security of messages against this adversary, in comparison to the security of: o email messages encrypted with PGP; o messages sent as application data in a TLS 1.3 session. 2. If several messages are sent in the same direction in the Signal protocol, how does their security compare to the security of messages sent successively in opposite directions?

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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