Mercurial > dropbear
changeset 1175:1b8afc698e39
check for zero K value from curve25519
| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Wed, 25 Nov 2015 22:15:59 +0800 |
| parents | 80cacacfec23 |
| children | 424822a6f8ee |
| files | common-kex.c |
| diffstat | 1 files changed, 6 insertions(+), 0 deletions(-) [+] |
line wrap: on
line diff
--- a/common-kex.c Wed Nov 25 20:46:06 2015 +0800 +++ b/common-kex.c Wed Nov 25 22:15:59 2015 +0800 @@ -760,6 +760,7 @@ unsigned char out[CURVE25519_LEN]; const unsigned char* Q_C = NULL; const unsigned char* Q_S = NULL; + char zeroes[CURVE25519_LEN] = {0}; if (buf_pub_them->len != CURVE25519_LEN) { @@ -767,6 +768,11 @@ } curve25519_donna(out, param->priv, buf_pub_them->data); + + if (constant_time_memcmp(zeroes, out, CURVE25519_LEN) == 0) { + dropbear_exit("Bad curve25519"); + } + m_mp_alloc_init_multi(&ses.dh_K, NULL); bytes_to_mp(ses.dh_K, out, CURVE25519_LEN); m_burn(out, sizeof(out));