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comparison libtommath/bn_mp_exteuclid.c @ 1436:60fc6476e044

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Update to libtommath v1.0
author Matt Johnston <matt@ucc.asn.au>
date Sat, 24 Jun 2017 22:37:14 +0800
parents 18154dc469f5
children 8bba51a55704
comparison
equal deleted inserted replaced
1435:f849a5ca2efc 1436:60fc6476e044
1 #include <tommath.h> 1 #include <tommath_private.h>
2 #ifdef BN_MP_EXTEUCLID_C 2 #ifdef BN_MP_EXTEUCLID_C
3 /* LibTomMath, multiple-precision integer library -- Tom St Denis 3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
4 * 4 *
5 * LibTomMath is a library that provides multiple-precision 5 * LibTomMath is a library that provides multiple-precision
6 * integer arithmetic as well as number theoretic functionality. 6 * integer arithmetic as well as number theoretic functionality.
10 * additional optimizations in place. 10 * additional optimizations in place.
11 * 11 *
12 * The library is free for all purposes without any express 12 * The library is free for all purposes without any express
13 * guarantee it works. 13 * guarantee it works.
14 * 14 *
15 * Tom St Denis, [email protected], http://math.libtomcrypt.com 15 * Tom St Denis, [email protected], http://libtom.org
16 */ 16 */
17 17
18 /* Extended euclidean algorithm of (a, b) produces 18 /* Extended euclidean algorithm of (a, b) produces
19 a*u1 + b*u2 = u3 19 a*u1 + b*u2 = u3
20 */ 20 */
21 int mp_exteuclid(mp_int *a, mp_int *b, mp_int *U1, mp_int *U2, mp_int *U3) 21 int mp_exteuclid(mp_int *a, mp_int *b, mp_int *U1, mp_int *U2, mp_int *U3)
22 { 22 {
23 mp_int u1,u2,u3,v1,v2,v3,t1,t2,t3,q,tmp; 23 mp_int u1,u2,u3,v1,v2,v3,t1,t2,t3,q,tmp;
27 return err; 27 return err;
28 } 28 }
29 29
30 /* initialize, (u1,u2,u3) = (1,0,a) */ 30 /* initialize, (u1,u2,u3) = (1,0,a) */
31 mp_set(&u1, 1); 31 mp_set(&u1, 1);
32 if ((err = mp_copy(a, &u3)) != MP_OKAY) { goto LBL_ERR; } 32 if ((err = mp_copy(a, &u3)) != MP_OKAY) { goto _ERR; }
33 33
34 /* initialize, (v1,v2,v3) = (0,1,b) */ 34 /* initialize, (v1,v2,v3) = (0,1,b) */
35 mp_set(&v2, 1); 35 mp_set(&v2, 1);
36 if ((err = mp_copy(b, &v3)) != MP_OKAY) { goto LBL_ERR; } 36 if ((err = mp_copy(b, &v3)) != MP_OKAY) { goto _ERR; }
37 37
38 /* loop while v3 != 0 */ 38 /* loop while v3 != 0 */
39 while (mp_iszero(&v3) == MP_NO) { 39 while (mp_iszero(&v3) == MP_NO) {
40 /* q = u3/v3 */ 40 /* q = u3/v3 */
41 if ((err = mp_div(&u3, &v3, &q, NULL)) != MP_OKAY) { goto LBL_ERR; } 41 if ((err = mp_div(&u3, &v3, &q, NULL)) != MP_OKAY) { goto _ERR; }
42 42
43 /* (t1,t2,t3) = (u1,u2,u3) - (v1,v2,v3)q */ 43 /* (t1,t2,t3) = (u1,u2,u3) - (v1,v2,v3)q */
44 if ((err = mp_mul(&v1, &q, &tmp)) != MP_OKAY) { goto LBL_ERR; } 44 if ((err = mp_mul(&v1, &q, &tmp)) != MP_OKAY) { goto _ERR; }
45 if ((err = mp_sub(&u1, &tmp, &t1)) != MP_OKAY) { goto LBL_ERR; } 45 if ((err = mp_sub(&u1, &tmp, &t1)) != MP_OKAY) { goto _ERR; }
46 if ((err = mp_mul(&v2, &q, &tmp)) != MP_OKAY) { goto LBL_ERR; } 46 if ((err = mp_mul(&v2, &q, &tmp)) != MP_OKAY) { goto _ERR; }
47 if ((err = mp_sub(&u2, &tmp, &t2)) != MP_OKAY) { goto LBL_ERR; } 47 if ((err = mp_sub(&u2, &tmp, &t2)) != MP_OKAY) { goto _ERR; }
48 if ((err = mp_mul(&v3, &q, &tmp)) != MP_OKAY) { goto LBL_ERR; } 48 if ((err = mp_mul(&v3, &q, &tmp)) != MP_OKAY) { goto _ERR; }
49 if ((err = mp_sub(&u3, &tmp, &t3)) != MP_OKAY) { goto LBL_ERR; } 49 if ((err = mp_sub(&u3, &tmp, &t3)) != MP_OKAY) { goto _ERR; }
50 50
51 /* (u1,u2,u3) = (v1,v2,v3) */ 51 /* (u1,u2,u3) = (v1,v2,v3) */
52 if ((err = mp_copy(&v1, &u1)) != MP_OKAY) { goto LBL_ERR; } 52 if ((err = mp_copy(&v1, &u1)) != MP_OKAY) { goto _ERR; }
53 if ((err = mp_copy(&v2, &u2)) != MP_OKAY) { goto LBL_ERR; } 53 if ((err = mp_copy(&v2, &u2)) != MP_OKAY) { goto _ERR; }
54 if ((err = mp_copy(&v3, &u3)) != MP_OKAY) { goto LBL_ERR; } 54 if ((err = mp_copy(&v3, &u3)) != MP_OKAY) { goto _ERR; }
55 55
56 /* (v1,v2,v3) = (t1,t2,t3) */ 56 /* (v1,v2,v3) = (t1,t2,t3) */
57 if ((err = mp_copy(&t1, &v1)) != MP_OKAY) { goto LBL_ERR; } 57 if ((err = mp_copy(&t1, &v1)) != MP_OKAY) { goto _ERR; }
58 if ((err = mp_copy(&t2, &v2)) != MP_OKAY) { goto LBL_ERR; } 58 if ((err = mp_copy(&t2, &v2)) != MP_OKAY) { goto _ERR; }
59 if ((err = mp_copy(&t3, &v3)) != MP_OKAY) { goto LBL_ERR; } 59 if ((err = mp_copy(&t3, &v3)) != MP_OKAY) { goto _ERR; }
60 } 60 }
61 61
62 /* make sure U3 >= 0 */ 62 /* make sure U3 >= 0 */
63 if (u3.sign == MP_NEG) { 63 if (u3.sign == MP_NEG) {
64 mp_neg(&u1, &u1); 64 if ((err = mp_neg(&u1, &u1)) != MP_OKAY) { goto _ERR; }
65 mp_neg(&u2, &u2); 65 if ((err = mp_neg(&u2, &u2)) != MP_OKAY) { goto _ERR; }
66 mp_neg(&u3, &u3); 66 if ((err = mp_neg(&u3, &u3)) != MP_OKAY) { goto _ERR; }
67 } 67 }
68 68
69 /* copy result out */ 69 /* copy result out */
70 if (U1 != NULL) { mp_exch(U1, &u1); } 70 if (U1 != NULL) { mp_exch(U1, &u1); }
71 if (U2 != NULL) { mp_exch(U2, &u2); } 71 if (U2 != NULL) { mp_exch(U2, &u2); }
72 if (U3 != NULL) { mp_exch(U3, &u3); } 72 if (U3 != NULL) { mp_exch(U3, &u3); }
73 73
74 err = MP_OKAY; 74 err = MP_OKAY;
75 LBL_ERR: 75 _ERR: mp_clear_multi(&u1, &u2, &u3, &v1, &v2, &v3, &t1, &t2, &t3, &q, &tmp, NULL);
76 mp_clear_multi(&u1, &u2, &u3, &v1, &v2, &v3, &t1, &t2, &t3, &q, &tmp, NULL);
77 return err; 76 return err;
78 } 77 }
79 #endif 78 #endif
80 79
81 /* $Source: /cvs/libtom/libtommath/bn_mp_exteuclid.c,v $ */ 80 /* $Source$ */
82 /* $Revision: 1.3 $ */ 81 /* $Revision$ */
83 /* $Date: 2006/03/31 14:18:44 $ */ 82 /* $Date$ */