annotate bn_mp_dr_is_modulus.c @ 139:cc04b085e7dd libtommath

Pristine compilation works.
author Matt Johnston <matt@ucc.asn.au>
date Fri, 17 Dec 2004 06:27:22 +0000
parents 22d5cf7d4b1a
children d29b64170cf0
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1 /* LibTomMath, multiple-precision integer library -- Tom St Denis
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2 *
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3 * LibTomMath is a library that provides multiple-precision
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4 * integer arithmetic as well as number theoretic functionality.
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5 *
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6 * The library was designed directly after the MPI library by
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7 * Michael Fromberger but has been written from scratch with
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8 * additional optimizations in place.
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9 *
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10 * The library is free for all purposes without any express
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11 * guarantee it works.
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12 *
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13 * Tom St Denis, [email protected], http://math.libtomcrypt.org
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14 */
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15 #include <tommath.h>
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17 /* determines if a number is a valid DR modulus */
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18 int mp_dr_is_modulus(mp_int *a)
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19 {
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20 int ix;
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21
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22 /* must be at least two digits */
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23 if (a->used < 2) {
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24 return 0;
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25 }
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27 /* must be of the form b**k - a [a <= b] so all
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28 * but the first digit must be equal to -1 (mod b).
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29 */
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30 for (ix = 1; ix < a->used; ix++) {
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31 if (a->dp[ix] != MP_MASK) {
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32 return 0;
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33 }
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34 }
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35 return 1;
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36 }
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