Mercurial > dropbear
diff random.c @ 272:3be7ae2e8dfa
Only read /dev/random once when the program starts
rather than for every connection, to "conserve entropy".
author | Matt Johnston <matt@ucc.asn.au> |
---|---|
date | Sat, 11 Feb 2006 15:15:37 +0000 |
parents | 65585699d980 |
children | 79bf1023cf11 7dad470ad4aa |
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--- a/random.c Wed Feb 01 09:05:13 2006 +0000 +++ b/random.c Sat Feb 11 15:15:37 2006 +0000 @@ -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 @@ 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 @@ 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) {