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Reduce per-packet overhead when using WEP by using an advancing IV

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seeded with arc4random rather than calling arc4random for each
packet.  Note this is the same algorithm used to select the IV when
doing WEP on the host.
This commit is contained in:
Sam Leffler 2003-10-13 03:42:53 +00:00
parent 167ecdca8c
commit 91101a2af3
1 changed files with 8 additions and 1 deletions
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9
sys/dev/ath/if_ath.c
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@ -1735,7 +1735,14 @@ ath_tx_start(struct ath_softc *sc, struct ieee80211_node *ni, struct ath_buf *bf
* So we use pseudo random IV for now, though it is not the
* right way.
*/
iv = arc4random();
iv = ic->ic_iv;
/*
* Skip 'bad' IVs from Fluhrer/Mantin/Shamir:
* (B, 255, N) with 3 <= B < 8
*/
if (iv >= 0x03ff00 && (iv & 0xf8ff00) == 0x00ff00)
iv += 0x000100;
ic->ic_iv = iv + 1;
for (i = 0; i < IEEE80211_WEP_IVLEN; i++) {
ivp[i] = iv;
iv >>= 8;