From d57ed660409fc7eed8a1308f1de47d5b73501b83 Mon Sep 17 00:00:00 2001 From: djm Date: Fri, 16 Jul 2010 14:07:35 +0000 Subject: [PATCH] more timing paranoia - compare all parts of the expected decrypted data before returning. AFAIK not exploitable in the SSH protocol. "groovy" deraadt@ --- usr.bin/ssh/ssh-rsa.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/usr.bin/ssh/ssh-rsa.c b/usr.bin/ssh/ssh-rsa.c index 08ee9e290ac..b29546783a2 100644 --- a/usr.bin/ssh/ssh-rsa.c +++ b/usr.bin/ssh/ssh-rsa.c @@ -1,4 +1,4 @@ -/* $OpenBSD: ssh-rsa.c,v 1.43 2010/07/13 23:13:16 djm Exp $ */ +/* $OpenBSD: ssh-rsa.c,v 1.44 2010/07/16 14:07:35 djm Exp $ */ /* * Copyright (c) 2000, 2003 Markus Friedl * @@ -208,7 +208,7 @@ openssh_RSA_verify(int type, u_char *hash, u_int hashlen, u_char *sigbuf, u_int siglen, RSA *rsa) { u_int ret, rsasize, oidlen = 0, hlen = 0; - int len; + int len, oidmatch, hashmatch; const u_char *oid = NULL; u_char *decrypted = NULL; @@ -247,11 +247,13 @@ openssh_RSA_verify(int type, u_char *hash, u_int hashlen, error("bad decrypted len: %d != %d + %d", len, hlen, oidlen); goto done; } - if (timingsafe_bcmp(decrypted, oid, oidlen) != 0) { + oidmatch = timingsafe_bcmp(decrypted, oid, oidlen) == 0; + hashmatch = timingsafe_bcmp(decrypted + oidlen, hash, hlen) == 0; + if (!oidmatch) { error("oid mismatch"); goto done; } - if (timingsafe_bcmp(decrypted + oidlen, hash, hlen) != 0) { + if (!hashmatch) { error("hash mismatch"); goto done; } -- 2.20.1