Date: Tue, 16 Dec 2008 13:58:37 +0000 (UTC) From: Alexander Motin <mav@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r186179 - head/sys/crypto/rc4 Message-ID: <200812161358.mBGDwbL5039244@svn.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: mav Date: Tue Dec 16 13:58:37 2008 New Revision: 186179 URL: http://svn.freebsd.org/changeset/base/186179 Log: Avoid 256 integer divisions per rc4_init() call. Replace it with using separate index variable. It gives more then double rc4_init() performance increase on tested i386 P4. It also gives about 15% speedup to PPTP VPN with stateless MPPE encryption (by ng_mppc) which calls rc4_init() for every packet. Modified: head/sys/crypto/rc4/rc4.c Modified: head/sys/crypto/rc4/rc4.c ============================================================================== --- head/sys/crypto/rc4/rc4.c Tue Dec 16 11:06:30 2008 (r186178) +++ head/sys/crypto/rc4/rc4.c Tue Dec 16 13:58:37 2008 (r186179) @@ -61,7 +61,7 @@ void rc4_init(struct rc4_state *const state, const u_char *key, int keylen) { u_char j; - int i; + int i, k; /* Initialize state with identity permutation */ for (i = 0; i < 256; i++) @@ -70,9 +70,11 @@ rc4_init(struct rc4_state *const state, state->index2 = 0; /* Randomize the permutation using key data */ - for (j = i = 0; i < 256; i++) { - j += state->perm[i] + key[i % keylen]; + for (j = i = k = 0; i < 256; i++) { + j += state->perm[i] + key[k]; swap_bytes(&state->perm[i], &state->perm[j]); + if (++k >= keylen) + k = 0; } }
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200812161358.mBGDwbL5039244>