Index: libsrtp/crypto/math/gf2_8.c |
=================================================================== |
--- libsrtp/crypto/math/gf2_8.c (revision 0) |
+++ libsrtp/crypto/math/gf2_8.c (revision 0) |
@@ -0,0 +1,83 @@ |
+/* |
+ * gf2_8.c |
+ * |
+ * GF(256) finite field implementation, with the representation used |
+ * in the AES cipher. |
+ * |
+ * David A. McGrew |
+ * Cisco Systems, Inc. |
+ */ |
+ |
+/* |
+ * |
+ * Copyright (c) 2001-2006, Cisco Systems, Inc. |
+ * All rights reserved. |
+ * |
+ * Redistribution and use in source and binary forms, with or without |
+ * modification, are permitted provided that the following conditions |
+ * are met: |
+ * |
+ * Redistributions of source code must retain the above copyright |
+ * notice, this list of conditions and the following disclaimer. |
+ * |
+ * Redistributions in binary form must reproduce the above |
+ * copyright notice, this list of conditions and the following |
+ * disclaimer in the documentation and/or other materials provided |
+ * with the distribution. |
+ * |
+ * Neither the name of the Cisco Systems, Inc. nor the names of its |
+ * contributors may be used to endorse or promote products derived |
+ * from this software without specific prior written permission. |
+ * |
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
+ * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, |
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR |
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
+ * OF THE POSSIBILITY OF SUCH DAMAGE. |
+ * |
+ */ |
+ |
+ |
+#include "datatypes.h" |
+#include "gf2_8.h" |
+ |
+/* gf2_8_shift() moved to gf2_8.h as an inline function */ |
+ |
+inline gf2_8 |
+gf2_8_multiply(gf2_8 x, gf2_8 y) { |
+ gf2_8 z = 0; |
+ |
+ if (y & 1) z ^= x; x = gf2_8_shift(x); |
+ if (y & 2) z ^= x; x = gf2_8_shift(x); |
+ if (y & 4) z ^= x; x = gf2_8_shift(x); |
+ if (y & 8) z ^= x; x = gf2_8_shift(x); |
+ if (y & 16) z ^= x; x = gf2_8_shift(x); |
+ if (y & 32) z ^= x; x = gf2_8_shift(x); |
+ if (y & 64) z ^= x; x = gf2_8_shift(x); |
+ if (y & 128) z ^= x; |
+ |
+ return z; |
+} |
+ |
+ |
+/* this should use the euclidean algorithm */ |
+ |
+gf2_8 |
+gf2_8_compute_inverse(gf2_8 x) { |
+ unsigned int i; |
+ |
+ if (x == 0) return 0; /* zero is a special case */ |
+ for (i=0; i < 256; i++) |
+ if (gf2_8_multiply((gf2_8) i, x) == 1) |
+ return (gf2_8) i; |
+ |
+ return 0; |
+} |
+ |
Property changes on: libsrtp/crypto/math/gf2_8.c |
___________________________________________________________________ |
Added: svn:eol-style |
+ LF |