5 * Modular exponentiation using Barrett reduction
7 * (c) 2004 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Catacomb.
14 * Catacomb is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
19 * Catacomb is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU Library General Public License for more details.
24 * You should have received a copy of the GNU Library General Public
25 * License along with Catacomb; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
30 /*----- Header files ------------------------------------------------------*/
33 #include "mpbarrett.h"
34 #include "mpbarrett-exp.h"
36 /*----- Main code ---------------------------------------------------------*/
38 /* --- @mpbarrett_exp@ --- *
40 * Arguments: @mpbarrett *mb@ = pointer to Barrett reduction context
41 * @mp *d@ = fake destination
45 * Returns: Result, %$a^e \bmod m$%.
48 mp
*mpbarrett_exp(mpbarrett
*mb
, mp
*d
, mp
*a
, mp
*e
)
51 mp
*spare
= (e
->f
& MP_BURN
) ? MP_NEWSEC
: MP_NEW
;
59 a
= mp_modinv(a
, a
, mb
->m
);
60 if (MP_LEN(e
) < EXP_THRESH
)
71 /*----- Test rig ----------------------------------------------------------*/
75 static int vexp(dstr
*v
)
77 mp
*m
= *(mp
**)v
[0].buf
;
78 mp
*a
= *(mp
**)v
[1].buf
;
79 mp
*b
= *(mp
**)v
[2].buf
;
80 mp
*r
= *(mp
**)v
[3].buf
;
85 mpbarrett_create(&mb
, m
);
87 mr
= mpbarrett_exp(&mb
, MP_NEW
, a
, b
);
90 fputs("\n*** barrett modexp failed", stderr
);
91 fputs("\n m = ", stderr
); mp_writefile(m
, stderr
, 10);
92 fputs("\n a = ", stderr
); mp_writefile(a
, stderr
, 10);
93 fputs("\n e = ", stderr
); mp_writefile(b
, stderr
, 10);
94 fputs("\n r = ", stderr
); mp_writefile(r
, stderr
, 10);
95 fputs("\nmr = ", stderr
); mp_writefile(mr
, stderr
, 10);
105 mpbarrett_destroy(&mb
);
106 assert(mparena_count(MPARENA_GLOBAL
) == 0);
110 static test_chunk tests
[] = {
111 { "mpbarrett-exp", vexp
, { &type_mp
, &type_mp
, &type_mp
, &type_mp
, 0 } },
115 int main(int argc
, char *argv
[])
118 test_run(argc
, argv
, tests
, SRCDIR
"/tests/mpbarrett");
124 /*----- That's all, folks -------------------------------------------------*/