Attachment 3606 Details for Bug 3467 – Make rekey interval less predictable.

[patch] Make rekey interval less predictable.

0001-Adapted-from-OpenBSD-arc4random-upstream-make-rekey-.patch (text/plain), 1.60 KB, created by Loganaden Velvindron on 2022-08-03 22:33:51 AEST

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Creator: Loganaden Velvindron

Created: 2022-08-03 22:33:51 AEST

Size: 1.60 KB

patch

obsolete

>From 44b037b5b7d028997b7986387411d19853044ce7 Mon Sep 17 00:00:00 2001
>From: Loganaden Velvindron <logan@cyberstorm.mu>
>Date: Wed, 3 Aug 2022 15:38:37 +0400
>Subject: [PATCH] Adapted from OpenBSD arc4random upstream: make rekey interval
> less predictable
>
>Signed-off-by: Loganaden Velvindron <logan@cyberstorm.mu>
>---
> openbsd-compat/arc4random.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
>diff --git a/openbsd-compat/arc4random.c b/openbsd-compat/arc4random.c
>index ce5f054f..661d769e 100644
>--- a/openbsd-compat/arc4random.c
>+++ b/openbsd-compat/arc4random.c
>@@ -1,6 +1,6 @@
> /* OPENBSD ORIGINAL: lib/libc/crypto/arc4random.c */
> 
>-/*	$OpenBSD: arc4random.c,v 1.25 2013/10/01 18:34:57 markus Exp $	*/
>+/*	$OpenBSD: arc4random.c,v 1.57 2022/07/31 05:10:36 djm Exp $	*/
> 
> /*
>  * Copyright (c) 1996, David Mazieres <dm@uun.org>
>@@ -65,6 +65,8 @@
> #define IVSZ	8
> #define BLOCKSZ	64
> #define RSBUFSZ	(16*BLOCKSZ)
>+#define REKEY_BASE (1024*1024) /* NB. should be a power of 2 */
>+
> static int rs_initialized;
> static pid_t rs_stir_pid;
> static chacha_ctx rs;		/* chacha context for random keystream */
>@@ -125,6 +127,7 @@ static void
> _rs_stir(void)
> {
> 	u_char rnd[KEYSZ + IVSZ];
>+	uint32_t rekey_fuzz = 0;
> 
> #ifdef WITH_OPENSSL
> 	if (RAND_bytes(rnd, sizeof(rnd)) <= 0)
>@@ -145,7 +148,10 @@ _rs_stir(void)
> 	rs_have = 0;
> 	memset(rs_buf, 0, RSBUFSZ);
> 
>-	rs_count = 1600000;
>+	/* rekey interval should not be predictable */
>+	chacha_encrypt_bytes(&rs, (uint8_t *)&rekey_fuzz,
>+	     (uint8_t *)&rekey_fuzz, sizeof(rekey_fuzz));
>+	rs_count = REKEY_BASE + (rekey_fuzz % REKEY_BASE);
> }
> 
> static inline void
>-- 
>2.17.1
>

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