diff options
| -rw-r--r-- | usr.bin/ssh/dh.c | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/usr.bin/ssh/dh.c b/usr.bin/ssh/dh.c index b32a7efb556..b3f4ceef1e8 100644 --- a/usr.bin/ssh/dh.c +++ b/usr.bin/ssh/dh.c @@ -1,4 +1,4 @@ -/* $OpenBSD: dh.c,v 1.35 2006/03/27 13:03:54 deraadt Exp $ */ +/* $OpenBSD: dh.c,v 1.36 2006/05/04 14:55:23 djm Exp $ */ /* * Copyright (c) 2000 Niels Provos. All rights reserved. * @@ -181,19 +181,36 @@ dh_pub_is_valid(DH *dh, BIGNUM *dh_pub) int i; int n = BN_num_bits(dh_pub); int bits_set = 0; + BIGNUM *tmp; if (dh_pub->neg) { logit("invalid public DH value: negativ"); return 0; } + if (BN_cmp(dh_pub, BN_value_one()) != 1) { /* pub_exp <= 1 */ + logit("invalid public DH value: <= 1"); + return 0; + } + + if ((tmp = BN_new()) == NULL) + return (-1); + if (!BN_sub(tmp, dh->p, BN_value_one()) || + BN_cmp(dh_pub, tmp) != -1) { /* pub_exp > p-2 */ + BN_clear_free(tmp); + logit("invalid public DH value: >= p-1"); + return 0; + } + BN_clear_free(tmp); + for (i = 0; i <= n; i++) if (BN_is_bit_set(dh_pub, i)) bits_set++; debug2("bits set: %d/%d", bits_set, BN_num_bits(dh->p)); /* if g==2 and bits_set==1 then computing log_g(dh_pub) is trivial */ - if (bits_set > 1 && (BN_cmp(dh_pub, dh->p) == -1)) + if (bits_set > 1) return 1; + logit("invalid public DH value (%d/%d)", bits_set, BN_num_bits(dh->p)); return 0; } |