Encrypt & Decrypt

basic info about cryptography

一文入门Cipher Suites: Ciphers, Algorithms and Negotiating Security Settings

The Transport Layer Security (TLS) Protocol Version 1.2, Version 1.3

Cipher suites are named combinations of:

  • Key Exchange Algorithms (RSA, DH, ECDH, DHE, ECDHE, PSK)
  • Authentication/Digital Signature Algorithm (RSA, ECDSA, DSA)
  • Bulk Encryption Algorithms (AES, CHACHA20, Camellia, ARIA)
  • Message Authentication Code Algorithms (SHA-256, POLY1305)

DH for Diffie–Hellman key exchange, What is the Diffie–Hellman key exchange and how does it work?, “Diffie-Hellman Key Exchange” in plain English

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official doc


This document describes how to create and verify EdDSA-compatible signatures using public key and private key formats initially defined for the X25519 and X448 elliptic curve Diffie-Hellman functions. This document also describes “VXEdDSA” which extends XEdDSA to make it a verifiable random function, or VRF.


This document describes the “X3DH” (or “Extended Triple Diffie-Hellman”) key agreement protocol. X3DH establishes a shared secret key between two parties who mutually authenticate each other based on public keys. X3DH provides forward secrecy and cryptographic deniability.

Double Ratchet

This document describes the Double Ratchet algorithm, which is used by two parties to exchange encrypted messages based on a shared secret key. The parties derive new keys for every Double Ratchet message so that earlier keys cannot be calculated from later ones. The parties also send Diffie-Hellman public values attached to their messages. The results of Diffie-Hellman calculations are mixed into the derived keys so that later keys cannot be calculated from earlier ones. These properties give some protection to earlier or later encrypted messages in case of a compromise of a party’s keys.


This document describes the Sesame algorithm for managing message encryption sessions in an asynchronous and multi-device setting.

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