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Small cleanups and comment fixes to rng functions.

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This commit is contained in:
Nick Mathewson 2015-12-09 09:15:57 -05:00
parent 2259de0de7
commit 3843c6615c
1 changed files with 9 additions and 4 deletions
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13
src/common/crypto.c
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@ -2344,14 +2344,18 @@ void
crypto_strongest_rand(uint8_t *out, size_t out_len)
{
const unsigned DLEN = SHA512_DIGEST_LENGTH;
/* We're going to hash DLEN bytes from the system RNG together with some
* bytes from the openssl PRNG, in order to yield DLEN bytes.
*/
uint8_t inp[DLEN*2];
uint8_t tmp[DLEN];
tor_assert(out);
while (out_len) {
crypto_rand((char*) inp+DLEN, DLEN);
if (crypto_strongest_rand_raw(inp, DLEN) < 0) {
crypto_rand((char*) inp, DLEN);
if (crypto_strongest_rand_raw(inp+DLEN, DLEN) < 0) {
log_err(LD_CRYPTO, "Failed to load strong entropy when generating an "
"important key. Exiting.");
/* Die with an assertion so we get a stack trace. */
tor_assert(0);
}
if (out_len >= DLEN) {
@ -2368,10 +2372,8 @@ crypto_strongest_rand(uint8_t *out, size_t out_len)
}
memwipe(tmp, 0, sizeof(tmp));
memwipe(inp, 0, sizeof(inp));
}
/** Seed OpenSSL's random number generator with bytes from the operating
* system. <b>startup</b> should be true iff we have just started Tor and
* have not yet allocated a bunch of fds. Return 0 on success, -1 on failure.
@ -2430,6 +2432,9 @@ crypto_rand_unmocked(char *to, size_t n)
tor_assert(n < INT_MAX);
tor_assert(to);
r = RAND_bytes((unsigned char*)to, (int)n);
/* We consider a PRNG failure non-survivable. Let's assert so that we get a
* stack trace about where it happened.
*/
tor_assert(r >= 0);
}