Mercurial > dropbear
annotate bn_mp_rand.c @ 200:c5c969ed76f3 libtommath
propagate from branch 'au.asn.ucc.matt.ltm-orig' (head 7fa10cba9535de3461cedb14b877c24858826204)
to branch 'au.asn.ucc.matt.dropbear.ltm' (head fc26f60de0370ab0a281fa41a2d13fb17c9d90a8)
| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Wed, 11 May 2005 16:15:27 +0000 |
| parents | d8254fc979e9 |
| children |
| rev | line source |
|---|---|
| 142 | 1 #include <tommath.h> |
| 2 #ifdef BN_MP_RAND_C | |
| 2 | 3 /* LibTomMath, multiple-precision integer library -- Tom St Denis |
| 4 * | |
| 5 * LibTomMath is a library that provides multiple-precision | |
| 6 * integer arithmetic as well as number theoretic functionality. | |
| 7 * | |
| 8 * The library was designed directly after the MPI library by | |
| 9 * Michael Fromberger but has been written from scratch with | |
| 10 * additional optimizations in place. | |
| 11 * | |
| 12 * The library is free for all purposes without any express | |
| 13 * guarantee it works. | |
| 14 * | |
| 15 * Tom St Denis, [email protected], http://math.libtomcrypt.org | |
| 16 */ | |
| 17 | |
| 18 /* makes a pseudo-random int of a given size */ | |
| 19 int | |
| 20 mp_rand (mp_int * a, int digits) | |
| 21 { | |
| 22 int res; | |
| 23 mp_digit d; | |
| 24 | |
| 25 mp_zero (a); | |
| 26 if (digits <= 0) { | |
| 27 return MP_OKAY; | |
| 28 } | |
| 29 | |
| 30 /* first place a random non-zero digit */ | |
| 31 do { | |
|
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parents:
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diff
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32 d = ((mp_digit) abs (rand ())) & MP_MASK; |
| 2 | 33 } while (d == 0); |
| 34 | |
| 35 if ((res = mp_add_d (a, d, a)) != MP_OKAY) { | |
| 36 return res; | |
| 37 } | |
| 38 | |
|
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parents:
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diff
changeset
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39 while (--digits > 0) { |
| 2 | 40 if ((res = mp_lshd (a, 1)) != MP_OKAY) { |
| 41 return res; | |
| 42 } | |
| 43 | |
| 44 if ((res = mp_add_d (a, ((mp_digit) abs (rand ())), a)) != MP_OKAY) { | |
| 45 return res; | |
| 46 } | |
| 47 } | |
| 48 | |
| 49 return MP_OKAY; | |
| 50 } | |
| 142 | 51 #endif |