diff options
Diffstat (limited to 'common-kex.c')
| -rw-r--r-- | common-kex.c | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/common-kex.c b/common-kex.c index 7d93708..f355560 100644 --- a/common-kex.c +++ b/common-kex.c @@ -629,16 +629,20 @@ void free_kexdh_param(struct kex_dh_param *param) void kexdh_comb_key(struct kex_dh_param *param, mp_int *dh_pub_them, sign_key *hostkey) { - mp_int dh_p; + DEF_MP_INT(dh_p); + DEF_MP_INT(dh_p_min1); mp_int *dh_e = NULL, *dh_f = NULL; - /* read the prime and generator*/ - m_mp_init(&dh_p); + m_mp_init_multi(&dh_p, &dh_p_min1, NULL); load_dh_p(&dh_p); - /* Check that dh_pub_them (dh_e or dh_f) is in the range [1, p-1] */ - if (mp_cmp(dh_pub_them, &dh_p) != MP_LT - || mp_cmp_d(dh_pub_them, 0) != MP_GT) { + if (mp_sub_d(&dh_p, 1, &dh_p_min1) != MP_OKAY) { + dropbear_exit("Diffie-Hellman error"); + } + + /* Check that dh_pub_them (dh_e or dh_f) is in the range [2, p-2] */ + if (mp_cmp(dh_pub_them, &dh_p_min1) != MP_LT + || mp_cmp_d(dh_pub_them, 1) != MP_GT) { dropbear_exit("Diffie-Hellman error"); } @@ -649,7 +653,7 @@ void kexdh_comb_key(struct kex_dh_param *param, mp_int *dh_pub_them, } /* clear no longer needed vars */ - mp_clear_multi(&dh_p, NULL); + mp_clear_multi(&dh_p, &dh_p_min1, NULL); /* From here on, the code needs to work with the _same_ vars on each side, * not vice-versaing for client/server */ |