From 223de8d94d6522f795ec3c2e7db27469f24aa68c Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Sun, 13 Jan 2019 10:51:17 -0800 Subject: Document RNG design in random.h --- src/random.cpp | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'src/random.cpp') diff --git a/src/random.cpp b/src/random.cpp index 4cd6c9ddc..3b7f7910b 100644 --- a/src/random.cpp +++ b/src/random.cpp @@ -282,6 +282,14 @@ namespace { class RNGState { Mutex m_mutex; + /* The RNG state consists of 256 bits of entropy, taken from the output of + * one operation's SHA512 output, and fed as input to the next one. + * Carrying 256 bits of entropy should be sufficient to guarantee + * unpredictability as long as any entropy source was ever unpredictable + * to an attacker. To protect against situations where an attacker might + * observe the RNG's state, fresh entropy is always mixed when + * GetStrongRandBytes is called. + */ unsigned char m_state[32] GUARDED_BY(m_mutex) = {0}; uint64_t m_counter GUARDED_BY(m_mutex) = 0; bool m_strongly_seeded GUARDED_BY(m_mutex) = false; -- cgit v1.2.3