From 1eb9209afef2046bbf74f8d2ffb0f357bdb992bb Mon Sep 17 00:00:00 2001 From: Matt Johnston Date: Sat, 11 Feb 2006 15:15:37 +0000 Subject: Only read /dev/random once when the program starts rather than for every connection, to "conserve entropy". --HG-- extra : convert_revision : 21df240b71c0af8454725dec9abb428dd4bb97a2 --- random.c | 31 ++++++++++++++++++++++++++++--- 1 file changed, 28 insertions(+), 3 deletions(-) (limited to 'random.c') diff --git a/random.c b/random.c index d58c8a8..cbbe016 100644 --- a/random.c +++ b/random.c @@ -30,8 +30,8 @@ static int donerandinit = 0; /* this is used to generate unique output from the same hashpool */ -static unsigned int counter = 0; -#define MAX_COUNTER 1000000/* the max value for the counter, so it won't loop */ +static uint32_t counter = 0; +#define MAX_COUNTER 1<<31 /* the max value for the counter, so it won't loop */ static unsigned char hashpool[SHA1_HASH_SIZE]; @@ -132,7 +132,8 @@ void seedrandom() { hash_state hs; - /* initialise so compilers will be happy about hashing it */ + /* initialise so that things won't warn about + * hashing an undefined buffer */ if (!donerandinit) { m_burn(hashpool, sizeof(hashpool)); } @@ -150,6 +151,30 @@ void seedrandom() { donerandinit = 1; } +/* hash the current random pool with some unique identifiers + * for this process and point-in-time. this is used to separate + * the random pools for fork()ed processes. */ +void reseedrandom() { + + pid_t pid; + struct timeval tv; + + if (!donerandinit) { + dropbear_exit("seedrandom not done"); + } + + pid = getpid(); + gettimeofday(&tv, NULL); + + hash_state hs; + unsigned char hash[SHA1_HASH_SIZE]; + sha1_init(&hs); + sha1_process(&hs, (void*)hashpool, sizeof(hashpool)); + sha1_process(&hs, (void*)&pid, sizeof(pid)); + sha1_process(&hs, (void*)&tv, sizeof(tv)); + sha1_done(&hs, hashpool); +} + /* return len bytes of pseudo-random data */ void genrandom(unsigned char* buf, unsigned int len) { -- cgit v1.2.3