3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
5 * LibTomMath is a library that provides multiple-precision
6 * integer arithmetic as well as number theoretic functionality.
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.
12 * The library is free for all purposes without any express
15 * Tom St Denis, tomstdenis@iahu.ca, http://math.libtomcrypt.org
18 /* calculate c = a**b using a square-multiply algorithm */
19 int mp_expt_d (mp_int * a, mp_digit b, mp_int * c)
24 if ((res = mp_init_copy (&g, a)) != MP_OKAY) {
28 /* set initial result */
31 for (x = 0; x < (int) DIGIT_BIT; x++) {
33 if ((res = mp_sqr (c, c)) != MP_OKAY) {
38 /* if the bit is set multiply */
39 if ((b & (mp_digit) (((mp_digit)1) << (DIGIT_BIT - 1))) != 0) {
40 if ((res = mp_mul (c, &g, c)) != MP_OKAY) {
46 /* shift to next bit */