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Sync arc4random(3) implementation from OpenBSD

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Closes: #12
This commit is contained in:
Guillem Jover
2022-08-03 02:03:05 +02:00
parent 873639ebb5
commit 1f6a48b209
3 changed files with 15 additions and 9 deletions
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14
src/arc4random.c
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@@ -1,4 +1,4 @@
/* $OpenBSD: arc4random.c,v 1.53 2015/09/10 18:53:50 bcook Exp $ */
/* $OpenBSD: arc4random.c,v 1.58 2022/07/31 13:41:45 tb Exp $ */
/*
* Copyright (c) 1996, David Mazieres <dm@uun.org>
@@ -50,6 +50,8 @@
#define BLOCKSZ 64
#define RSBUFSZ (16*BLOCKSZ)
#define REKEY_BASE (1024*1024) /* NB. should be a power of 2 */
/* Marked MAP_INHERIT_ZERO, so zero'd out in fork children. */
static struct _rs {
size_t rs_have; /* valid bytes at end of rs_buf */
@@ -74,10 +76,10 @@ _rs_init(unsigned char *buf, size_t n)
if (rs == NULL) {
if (_rs_allocate(&rs, &rsx) == -1)
abort();
_exit(1);
}
chacha_keysetup(&rsx->rs_chacha, buf, KEYSZ * 8, 0);
chacha_keysetup(&rsx->rs_chacha, buf, KEYSZ * 8);
chacha_ivsetup(&rsx->rs_chacha, buf + KEYSZ);
}
@@ -108,6 +110,7 @@ static void
_rs_stir(void)
{
unsigned char rnd[KEYSZ + IVSZ];
uint32_t rekey_fuzz = 0;
if (getentropy(rnd, sizeof rnd) == -1)
_getentropy_fail();
@@ -122,7 +125,10 @@ _rs_stir(void)
rs->rs_have = 0;
memset(rsx->rs_buf, 0, sizeof(rsx->rs_buf));
rs->rs_count = 1600000;
/* rekey interval should not be predictable */
chacha_encrypt_bytes(&rsx->rs_chacha, (uint8_t *)&rekey_fuzz,
(uint8_t *)&rekey_fuzz, sizeof(rekey_fuzz));
rs->rs_count = REKEY_BASE + (rekey_fuzz % REKEY_BASE);
}
static inline void