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1 /* | |
2 * gf2_8.h | |
3 * | |
4 * GF(256) implementation | |
5 * | |
6 * David A. McGrew | |
7 * Cisco Systems, Inc. | |
8 */ | |
9 | |
10 /* | |
11 * | |
12 * Copyright (c) 2001-2006, Cisco Systems, Inc. | |
13 * All rights reserved. | |
14 * | |
15 * Redistribution and use in source and binary forms, with or without | |
16 * modification, are permitted provided that the following conditions | |
17 * are met: | |
18 * | |
19 * Redistributions of source code must retain the above copyright | |
20 * notice, this list of conditions and the following disclaimer. | |
21 * | |
22 * Redistributions in binary form must reproduce the above | |
23 * copyright notice, this list of conditions and the following | |
24 * disclaimer in the documentation and/or other materials provided | |
25 * with the distribution. | |
26 * | |
27 * Neither the name of the Cisco Systems, Inc. nor the names of its | |
28 * contributors may be used to endorse or promote products derived | |
29 * from this software without specific prior written permission. | |
30 * | |
31 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
32 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
33 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS | |
34 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE | |
35 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, | |
36 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES | |
37 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR | |
38 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
39 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
40 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
41 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED | |
42 * OF THE POSSIBILITY OF SUCH DAMAGE. | |
43 * | |
44 */ | |
45 | |
46 | |
47 #ifndef GF2_8_H | |
48 #define GF2_8_H | |
49 | |
50 #include "datatypes.h" /* for uint8_t definition */ | |
51 | |
52 typedef uint8_t gf2_8; | |
53 | |
54 #define gf2_8_field_polynomial 0x1B | |
55 | |
56 /* | |
57 * gf2_8_shift(x) returns | |
58 */ | |
59 | |
60 /* | |
61 * gf2_8_shift(z) returns the result of the GF(2^8) 'multiply by x' | |
62 * operation, using the field representation from AES; that is, the | |
63 * next gf2_8 value in the cyclic representation of that field. The | |
64 * value z should be an uint8_t. | |
65 */ | |
66 | |
67 #define gf2_8_shift(z) (((z) & 128) ? \ | |
68 (((z) << 1) ^ gf2_8_field_polynomial) : ((z) << 1)) | |
69 | |
70 gf2_8 | |
71 gf2_8_compute_inverse(gf2_8 x); | |
72 | |
73 void | |
74 test_gf2_8(void); | |
75 | |
76 gf2_8 | |
77 gf2_8_multiply(gf2_8 x, gf2_8 y); | |
78 | |
79 #endif /* GF2_8_H */ | |
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