forked from boostorg/beast
Vinnie Falco
749e54f31b
This resolves a medium vulnerability described in the Beast Hybrid Assessment Report by Bishop Fox, where masks generated for use with outgoing WebSocket client frames use an insufficient source of entropy and a non-cryptographically secure pseudo-random number generator. By default, all newly constructed WebSocket streams will use a uniquely seeded secure PRNG (ChaCha20 in counter mode). As this may result in increased CPU resource consumption, the function websocket::stream::secure_prng() may be used to select a faster but less secure PRNG, for the case where the caller knows that the secure generator is not necessary. On some systems, std::random_device may produce insufficient entropy to securely seed the PRNG. As this condition cannot be detected by Beast, callers may use the function websocket::seed_prng() called once at startup to provide at least 256 bits of entropy which will be used to uniquely seed all subsequent PRNGs.