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wifi: check tkip/ccmp mac and crc in constant time avoiding timing side channels

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This commit is contained in:
cinap_lenrek 2016-01-14 23:39:29 +01:00
parent a57a6e511f
commit 4a47b264ac
1 changed files with 3 additions and 4 deletions
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7
sys/src/9/pc/wifi.c
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@ -1429,8 +1429,7 @@ tkipdecrypt(Wkey *k, Wifipkt *w, Block *b, uvlong tsc)
(ulong)b->wp[2]<<16 |
(ulong)b->wp[3]<<24;
crc = ~crc;
if(ethercrc(b->rp, BLEN(b)) != crc)
return -1;
crc ^= ethercrc(b->rp, BLEN(b));
b->wp -= 8;
micsetup(&ms, k->key+16);
@ -1440,7 +1439,7 @@ tkipdecrypt(Wkey *k, Wifipkt *w, Block *b, uvlong tsc)
micupdate(&ms, b->rp, BLEN(b));
micfinish(&ms, mic);
return memcmp(b->wp, mic, 8) != 0;
return tsmemcmp(b->wp, mic, 8) | crc;
}
static uchar*
@ -1561,7 +1560,7 @@ aesCCMdecrypt(int L, int M, uchar *N /* N[15-L] */,
for(p = sblock(L, N, 0, b, s), x = t; p < &b[M]; x++, p++)
*x ^= *p;
return memcmp(m, t, M) != 0;
return tsmemcmp(m, t, M);
}
static int