A Review of Signal Security Protocols Suitable for Power-Limited Hardware

Instant messengers have been popularized by users for private and business communication as an alternative to the cheap short message system in mobile phones with limited computing power. However, until recently, most mobile messaging applications did not protect the confidentiality or integrity of messages. Due to reports of communications being intercepted by intelligence services such as the NSA, people have been motivated to look for alternative messengers to maintain the security and privacy of their communications on the Internet. Initially, with Facebook's purchase of the popular messaging app WhatsApp, other apps claiming to offer secure communications gained significant new users. One messaging app that claims to offer secure instant messaging features and has garnered a lot of attention is TextSecure Messenger. Next, Signal Messenger, which is considered the successor of TextSecure, uses the protocols available in this messenger to exchange text messages. Considering that the WhatsApp messenger is based on the signal protocol, in this article a complete description of the encryption complexity of the signal protocol is presented. In the following, a security analysis of the three main components of this protocol including: key exchange, key extraction and authentication in encrypted messages is described. It has also been shown that the process of sending and displaying messages in this protocol can achieve most of the security goals. Finally, the role of quantum attacks that resulted from the computing power of quantum computers in solving classical asymmetric cryptography problems in the security of the key agreement protocol used in the Signal was checked. It is also shown that the use of Post-Quantum key exchange cryptographic protocols can secure the key agreement part of the Signal protocol against attacks by quantum algorithms.