|
282
|
1 #include <tommath.h> |
|
|
2 #ifdef BN_MP_PRIME_IS_PRIME_C |
|
|
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 /* performs a variable number of rounds of Miller-Rabin |
|
|
19 * |
|
|
20 * Probability of error after t rounds is no more than |
|
|
21 |
|
|
22 * |
|
|
23 * Sets result to 1 if probably prime, 0 otherwise |
|
|
24 */ |
|
|
25 int mp_prime_is_prime (mp_int * a, int t, int *result) |
|
|
26 { |
|
|
27 mp_int b; |
|
|
28 int ix, err, res; |
|
|
29 |
|
|
30 /* default to no */ |
|
|
31 *result = MP_NO; |
|
|
32 |
|
|
33 /* valid value of t? */ |
|
|
34 if (t <= 0 || t > PRIME_SIZE) { |
|
|
35 return MP_VAL; |
|
|
36 } |
|
|
37 |
|
|
38 /* is the input equal to one of the primes in the table? */ |
|
|
39 for (ix = 0; ix < PRIME_SIZE; ix++) { |
|
|
40 if (mp_cmp_d(a, ltm_prime_tab[ix]) == MP_EQ) { |
|
|
41 *result = 1; |
|
|
42 return MP_OKAY; |
|
|
43 } |
|
|
44 } |
|
|
45 |
|
|
46 /* first perform trial division */ |
|
|
47 if ((err = mp_prime_is_divisible (a, &res)) != MP_OKAY) { |
|
|
48 return err; |
|
|
49 } |
|
|
50 |
|
|
51 /* return if it was trivially divisible */ |
|
|
52 if (res == MP_YES) { |
|
|
53 return MP_OKAY; |
|
|
54 } |
|
|
55 |
|
|
56 /* now perform the miller-rabin rounds */ |
|
|
57 if ((err = mp_init (&b)) != MP_OKAY) { |
|
|
58 return err; |
|
|
59 } |
|
|
60 |
|
|
61 for (ix = 0; ix < t; ix++) { |
|
|
62 /* set the prime */ |
|
|
63 mp_set (&b, ltm_prime_tab[ix]); |
|
|
64 |
|
|
65 if ((err = mp_prime_miller_rabin (a, &b, &res)) != MP_OKAY) { |
|
|
66 goto LBL_B; |
|
|
67 } |
|
|
68 |
|
|
69 if (res == MP_NO) { |
|
|
70 goto LBL_B; |
|
|
71 } |
|
|
72 } |
|
|
73 |
|
|
74 /* passed the test */ |
|
|
75 *result = MP_YES; |
|
|
76 LBL_B:mp_clear (&b); |
|
|
77 return err; |
|
|
78 } |
|
|
79 #endif |
