Date: Sun, 12 Oct 2003 20:25:15 -0700 (PDT) From: Sam Leffler <sam@FreeBSD.org> To: Perforce Change Reviews <perforce@freebsd.org> Subject: PERFORCE change 39616 for review Message-ID: <200310130325.h9D3PFm0084683@repoman.freebsd.org>
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http://perforce.freebsd.org/chv.cgi?CH=39616 Change 39616 by sam@sam_ebb on 2003/10/12 20:25:14 Reduce per-packet overhead when using WEP by using an advancing IV 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. Affected files ... .. //depot/projects/netperf/sys/dev/ath/if_ath.c#18 edit Differences ... ==== //depot/projects/netperf/sys/dev/ath/if_ath.c#18 (text+ko) ==== @@ -1735,7 +1735,14 @@ * 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;
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