The Noise Protocol is a framework for building secure, encrypted communication channels between two parties, such as two computers or two mobile devices. It uses a combination of cryptographic primitives to establish a secure channel, including symmetric encryption, public-key encryption, and digital signatures.
One of the key features of the Noise Protocol is its flexibility, which allows it to be adapted to different use cases and security requirements. For example, it can be used to provide forward secrecy, which ensures that even if an attacker obtains the long-term keys used for encryption, they cannot decrypt past messages. It can also be used to provide deniability, which means that neither party can prove to a third party that a conversation took place.
The Noise Protocol has been widely adopted by a number of projects and protocols, including the Signal messaging app, the Tor anonymity network, and the WireGuard VPN protocol. Its popularity is due in part to its security properties and flexibility, as well as its ease of implementation and integration with existing cryptographic libraries.