Mercurial > dropbear
annotate bn_mp_exteuclid.c @ 203:e109027b9edf libtommath LTM_DB_0.46 LTM_DB_0.47
Don't remove ~ files on make clean (and find -type was wrong anyway)
author | Matt Johnston <matt@ucc.asn.au> |
---|---|
date | Wed, 11 May 2005 16:27:28 +0000 |
parents | d8254fc979e9 |
children |
rev | line source |
---|---|
142 | 1 #include <tommath.h> |
2 #ifdef BN_MP_EXTEUCLID_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 /* Extended euclidean algorithm of (a, b) produces | |
19 a*u1 + b*u2 = u3 | |
20 */ | |
21 int mp_exteuclid(mp_int *a, mp_int *b, mp_int *U1, mp_int *U2, mp_int *U3) | |
22 { | |
23 mp_int u1,u2,u3,v1,v2,v3,t1,t2,t3,q,tmp; | |
24 int err; | |
25 | |
26 if ((err = mp_init_multi(&u1, &u2, &u3, &v1, &v2, &v3, &t1, &t2, &t3, &q, &tmp, NULL)) != MP_OKAY) { | |
27 return err; | |
28 } | |
29 | |
30 /* initialize, (u1,u2,u3) = (1,0,a) */ | |
31 mp_set(&u1, 1); | |
32 if ((err = mp_copy(a, &u3)) != MP_OKAY) { goto _ERR; } | |
33 | |
34 /* initialize, (v1,v2,v3) = (0,1,b) */ | |
35 mp_set(&v2, 1); | |
36 if ((err = mp_copy(b, &v3)) != MP_OKAY) { goto _ERR; } | |
37 | |
38 /* loop while v3 != 0 */ | |
39 while (mp_iszero(&v3) == MP_NO) { | |
40 /* q = u3/v3 */ | |
41 if ((err = mp_div(&u3, &v3, &q, NULL)) != MP_OKAY) { goto _ERR; } | |
42 | |
43 /* (t1,t2,t3) = (u1,u2,u3) - (v1,v2,v3)q */ | |
44 if ((err = mp_mul(&v1, &q, &tmp)) != MP_OKAY) { goto _ERR; } | |
45 if ((err = mp_sub(&u1, &tmp, &t1)) != MP_OKAY) { goto _ERR; } | |
46 if ((err = mp_mul(&v2, &q, &tmp)) != MP_OKAY) { goto _ERR; } | |
47 if ((err = mp_sub(&u2, &tmp, &t2)) != MP_OKAY) { goto _ERR; } | |
48 if ((err = mp_mul(&v3, &q, &tmp)) != MP_OKAY) { goto _ERR; } | |
49 if ((err = mp_sub(&u3, &tmp, &t3)) != MP_OKAY) { goto _ERR; } | |
50 | |
51 /* (u1,u2,u3) = (v1,v2,v3) */ | |
52 if ((err = mp_copy(&v1, &u1)) != MP_OKAY) { goto _ERR; } | |
53 if ((err = mp_copy(&v2, &u2)) != MP_OKAY) { goto _ERR; } | |
54 if ((err = mp_copy(&v3, &u3)) != MP_OKAY) { goto _ERR; } | |
55 | |
56 /* (v1,v2,v3) = (t1,t2,t3) */ | |
57 if ((err = mp_copy(&t1, &v1)) != MP_OKAY) { goto _ERR; } | |
58 if ((err = mp_copy(&t2, &v2)) != MP_OKAY) { goto _ERR; } | |
59 if ((err = mp_copy(&t3, &v3)) != MP_OKAY) { goto _ERR; } | |
60 } | |
61 | |
190
d8254fc979e9
Initial import of libtommath 0.35
Matt Johnston <matt@ucc.asn.au>
parents:
142
diff
changeset
|
62 /* make sure U3 >= 0 */ |
d8254fc979e9
Initial import of libtommath 0.35
Matt Johnston <matt@ucc.asn.au>
parents:
142
diff
changeset
|
63 if (u3.sign == MP_NEG) { |
d8254fc979e9
Initial import of libtommath 0.35
Matt Johnston <matt@ucc.asn.au>
parents:
142
diff
changeset
|
64 mp_neg(&u1, &u1); |
d8254fc979e9
Initial import of libtommath 0.35
Matt Johnston <matt@ucc.asn.au>
parents:
142
diff
changeset
|
65 mp_neg(&u2, &u2); |
d8254fc979e9
Initial import of libtommath 0.35
Matt Johnston <matt@ucc.asn.au>
parents:
142
diff
changeset
|
66 mp_neg(&u3, &u3); |
d8254fc979e9
Initial import of libtommath 0.35
Matt Johnston <matt@ucc.asn.au>
parents:
142
diff
changeset
|
67 } |
d8254fc979e9
Initial import of libtommath 0.35
Matt Johnston <matt@ucc.asn.au>
parents:
142
diff
changeset
|
68 |
2 | 69 /* copy result out */ |
70 if (U1 != NULL) { mp_exch(U1, &u1); } | |
71 if (U2 != NULL) { mp_exch(U2, &u2); } | |
72 if (U3 != NULL) { mp_exch(U3, &u3); } | |
73 | |
74 err = MP_OKAY; | |
75 _ERR: mp_clear_multi(&u1, &u2, &u3, &v1, &v2, &v3, &t1, &t2, &t3, &q, &tmp, NULL); | |
76 return err; | |
77 } | |
142 | 78 #endif |