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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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16 |
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17 /* makes a pseudo-random int of a given size */ |
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18 int |
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19 mp_rand (mp_int * a, int digits) |
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20 { |
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21 int res; |
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22 mp_digit d; |
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23 |
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24 mp_zero (a); |
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25 if (digits <= 0) { |
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26 return MP_OKAY; |
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27 } |
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28 |
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29 /* first place a random non-zero digit */ |
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30 do { |
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31 d = ((mp_digit) abs (rand ())); |
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32 } while (d == 0); |
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33 |
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34 if ((res = mp_add_d (a, d, a)) != MP_OKAY) { |
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35 return res; |
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36 } |
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37 |
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38 while (digits-- > 0) { |
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39 if ((res = mp_lshd (a, 1)) != MP_OKAY) { |
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40 return res; |
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41 } |
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42 |
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43 if ((res = mp_add_d (a, ((mp_digit) abs (rand ())), a)) != MP_OKAY) { |
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44 return res; |
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45 } |
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46 } |
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47 |
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48 return MP_OKAY; |
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49 } |
