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author | jan.nijtmans <nijtmans@users.sourceforge.net> | 2017-09-15 14:44:00 (GMT) |
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committer | jan.nijtmans <nijtmans@users.sourceforge.net> | 2017-09-15 14:44:00 (GMT) |
commit | 30f7e69b182d1267056ee2628a860891f6555aa3 (patch) | |
tree | 4598f9d64ea232476fcf18bbef6bd413444c0c07 /libtommath/bn_s_mp_exptmod.c | |
parent | b167e2845e3a2d5b2ffe3a877cb19c3f430aeacf (diff) | |
download | tcl-30f7e69b182d1267056ee2628a860891f6555aa3.zip tcl-30f7e69b182d1267056ee2628a860891f6555aa3.tar.gz tcl-30f7e69b182d1267056ee2628a860891f6555aa3.tar.bz2 |
re-format everything through astyle. Taken from libtom/libtommath (pull request [https://github.com/libtom/libtommath/pull/85|85])
Diffstat (limited to 'libtommath/bn_s_mp_exptmod.c')
-rw-r--r-- | libtommath/bn_s_mp_exptmod.c | 412 |
1 files changed, 207 insertions, 205 deletions
diff --git a/libtommath/bn_s_mp_exptmod.c b/libtommath/bn_s_mp_exptmod.c index ab820d4..f8e6b3b 100644 --- a/libtommath/bn_s_mp_exptmod.c +++ b/libtommath/bn_s_mp_exptmod.c @@ -15,235 +15,237 @@ * Tom St Denis, tstdenis82@gmail.com, http://libtom.org */ #ifdef MP_LOW_MEM - #define TAB_SIZE 32 +# define TAB_SIZE 32 #else - #define TAB_SIZE 256 +# define TAB_SIZE 256 #endif -int s_mp_exptmod (mp_int * G, mp_int * X, mp_int * P, mp_int * Y, int redmode) +int s_mp_exptmod(mp_int *G, mp_int *X, mp_int *P, mp_int *Y, int redmode) { - mp_int M[TAB_SIZE], res, mu; - mp_digit buf; - int err, bitbuf, bitcpy, bitcnt, mode, digidx, x, y, winsize; - int (*redux)(mp_int*,mp_int*,mp_int*); - - /* find window size */ - x = mp_count_bits (X); - if (x <= 7) { - winsize = 2; - } else if (x <= 36) { - winsize = 3; - } else if (x <= 140) { - winsize = 4; - } else if (x <= 450) { - winsize = 5; - } else if (x <= 1303) { - winsize = 6; - } else if (x <= 3529) { - winsize = 7; - } else { - winsize = 8; - } + mp_int M[TAB_SIZE], res, mu; + mp_digit buf; + int err, bitbuf, bitcpy, bitcnt, mode, digidx, x, y, winsize; + int (*redux)(mp_int *,mp_int *,mp_int *); + + /* find window size */ + x = mp_count_bits(X); + if (x <= 7) { + winsize = 2; + } else if (x <= 36) { + winsize = 3; + } else if (x <= 140) { + winsize = 4; + } else if (x <= 450) { + winsize = 5; + } else if (x <= 1303) { + winsize = 6; + } else if (x <= 3529) { + winsize = 7; + } else { + winsize = 8; + } #ifdef MP_LOW_MEM - if (winsize > 5) { - winsize = 5; - } + if (winsize > 5) { + winsize = 5; + } #endif - /* init M array */ - /* init first cell */ - if ((err = mp_init(&M[1])) != MP_OKAY) { - return err; - } - - /* now init the second half of the array */ - for (x = 1<<(winsize-1); x < (1 << winsize); x++) { - if ((err = mp_init(&M[x])) != MP_OKAY) { - for (y = 1<<(winsize-1); y < x; y++) { - mp_clear (&M[y]); - } - mp_clear(&M[1]); + /* init M array */ + /* init first cell */ + if ((err = mp_init(&M[1])) != MP_OKAY) { return err; - } - } - - /* create mu, used for Barrett reduction */ - if ((err = mp_init (&mu)) != MP_OKAY) { - goto LBL_M; - } - - if (redmode == 0) { - if ((err = mp_reduce_setup (&mu, P)) != MP_OKAY) { - goto LBL_MU; - } - redux = mp_reduce; - } else { - if ((err = mp_reduce_2k_setup_l (P, &mu)) != MP_OKAY) { - goto LBL_MU; - } - redux = mp_reduce_2k_l; - } - - /* create M table - * - * The M table contains powers of the base, - * e.g. M[x] = G**x mod P - * - * The first half of the table is not - * computed though accept for M[0] and M[1] - */ - if ((err = mp_mod (G, P, &M[1])) != MP_OKAY) { - goto LBL_MU; - } - - /* compute the value at M[1<<(winsize-1)] by squaring - * M[1] (winsize-1) times - */ - if ((err = mp_copy (&M[1], &M[1 << (winsize - 1)])) != MP_OKAY) { - goto LBL_MU; - } - - for (x = 0; x < (winsize - 1); x++) { - /* square it */ - if ((err = mp_sqr (&M[1 << (winsize - 1)], - &M[1 << (winsize - 1)])) != MP_OKAY) { - goto LBL_MU; - } + } + + /* now init the second half of the array */ + for (x = 1<<(winsize-1); x < (1 << winsize); x++) { + if ((err = mp_init(&M[x])) != MP_OKAY) { + for (y = 1<<(winsize-1); y < x; y++) { + mp_clear(&M[y]); + } + mp_clear(&M[1]); + return err; + } + } - /* reduce modulo P */ - if ((err = redux (&M[1 << (winsize - 1)], P, &mu)) != MP_OKAY) { - goto LBL_MU; - } - } - - /* create upper table, that is M[x] = M[x-1] * M[1] (mod P) - * for x = (2**(winsize - 1) + 1) to (2**winsize - 1) - */ - for (x = (1 << (winsize - 1)) + 1; x < (1 << winsize); x++) { - if ((err = mp_mul (&M[x - 1], &M[1], &M[x])) != MP_OKAY) { + /* create mu, used for Barrett reduction */ + if ((err = mp_init(&mu)) != MP_OKAY) { + goto LBL_M; + } + + if (redmode == 0) { + if ((err = mp_reduce_setup(&mu, P)) != MP_OKAY) { + goto LBL_MU; + } + redux = mp_reduce; + } else { + if ((err = mp_reduce_2k_setup_l(P, &mu)) != MP_OKAY) { + goto LBL_MU; + } + redux = mp_reduce_2k_l; + } + + /* create M table + * + * The M table contains powers of the base, + * e.g. M[x] = G**x mod P + * + * The first half of the table is not + * computed though accept for M[0] and M[1] + */ + if ((err = mp_mod(G, P, &M[1])) != MP_OKAY) { goto LBL_MU; - } - if ((err = redux (&M[x], P, &mu)) != MP_OKAY) { + } + + /* compute the value at M[1<<(winsize-1)] by squaring + * M[1] (winsize-1) times + */ + if ((err = mp_copy(&M[1], &M[1 << (winsize - 1)])) != MP_OKAY) { goto LBL_MU; - } - } - - /* setup result */ - if ((err = mp_init (&res)) != MP_OKAY) { - goto LBL_MU; - } - mp_set (&res, 1); - - /* set initial mode and bit cnt */ - mode = 0; - bitcnt = 1; - buf = 0; - digidx = X->used - 1; - bitcpy = 0; - bitbuf = 0; - - for (;;) { - /* grab next digit as required */ - if (--bitcnt == 0) { - /* if digidx == -1 we are out of digits */ - if (digidx == -1) { - break; + } + + for (x = 0; x < (winsize - 1); x++) { + /* square it */ + if ((err = mp_sqr(&M[1 << (winsize - 1)], + &M[1 << (winsize - 1)])) != MP_OKAY) { + goto LBL_MU; } - /* read next digit and reset the bitcnt */ - buf = X->dp[digidx--]; - bitcnt = (int) DIGIT_BIT; - } - - /* grab the next msb from the exponent */ - y = (buf >> (mp_digit)(DIGIT_BIT - 1)) & 1; - buf <<= (mp_digit)1; - - /* if the bit is zero and mode == 0 then we ignore it - * These represent the leading zero bits before the first 1 bit - * in the exponent. Technically this opt is not required but it - * does lower the # of trivial squaring/reductions used - */ - if ((mode == 0) && (y == 0)) { - continue; - } - - /* if the bit is zero and mode == 1 then we square */ - if ((mode == 1) && (y == 0)) { - if ((err = mp_sqr (&res, &res)) != MP_OKAY) { - goto LBL_RES; + + /* reduce modulo P */ + if ((err = redux(&M[1 << (winsize - 1)], P, &mu)) != MP_OKAY) { + goto LBL_MU; } - if ((err = redux (&res, P, &mu)) != MP_OKAY) { - goto LBL_RES; + } + + /* create upper table, that is M[x] = M[x-1] * M[1] (mod P) + * for x = (2**(winsize - 1) + 1) to (2**winsize - 1) + */ + for (x = (1 << (winsize - 1)) + 1; x < (1 << winsize); x++) { + if ((err = mp_mul(&M[x - 1], &M[1], &M[x])) != MP_OKAY) { + goto LBL_MU; } - continue; - } - - /* else we add it to the window */ - bitbuf |= (y << (winsize - ++bitcpy)); - mode = 2; - - if (bitcpy == winsize) { - /* ok window is filled so square as required and multiply */ - /* square first */ - for (x = 0; x < winsize; x++) { - if ((err = mp_sqr (&res, &res)) != MP_OKAY) { - goto LBL_RES; - } - if ((err = redux (&res, P, &mu)) != MP_OKAY) { - goto LBL_RES; - } + if ((err = redux(&M[x], P, &mu)) != MP_OKAY) { + goto LBL_MU; } + } - /* then multiply */ - if ((err = mp_mul (&res, &M[bitbuf], &res)) != MP_OKAY) { - goto LBL_RES; - } - if ((err = redux (&res, P, &mu)) != MP_OKAY) { - goto LBL_RES; + /* setup result */ + if ((err = mp_init(&res)) != MP_OKAY) { + goto LBL_MU; + } + mp_set(&res, 1); + + /* set initial mode and bit cnt */ + mode = 0; + bitcnt = 1; + buf = 0; + digidx = X->used - 1; + bitcpy = 0; + bitbuf = 0; + + for (;;) { + /* grab next digit as required */ + if (--bitcnt == 0) { + /* if digidx == -1 we are out of digits */ + if (digidx == -1) { + break; + } + /* read next digit and reset the bitcnt */ + buf = X->dp[digidx--]; + bitcnt = (int)DIGIT_BIT; } - /* empty window and reset */ - bitcpy = 0; - bitbuf = 0; - mode = 1; - } - } - - /* if bits remain then square/multiply */ - if ((mode == 2) && (bitcpy > 0)) { - /* square then multiply if the bit is set */ - for (x = 0; x < bitcpy; x++) { - if ((err = mp_sqr (&res, &res)) != MP_OKAY) { - goto LBL_RES; - } - if ((err = redux (&res, P, &mu)) != MP_OKAY) { - goto LBL_RES; + /* grab the next msb from the exponent */ + y = (buf >> (mp_digit)(DIGIT_BIT - 1)) & 1; + buf <<= (mp_digit)1; + + /* if the bit is zero and mode == 0 then we ignore it + * These represent the leading zero bits before the first 1 bit + * in the exponent. Technically this opt is not required but it + * does lower the # of trivial squaring/reductions used + */ + if ((mode == 0) && (y == 0)) { + continue; } - bitbuf <<= 1; - if ((bitbuf & (1 << winsize)) != 0) { - /* then multiply */ - if ((err = mp_mul (&res, &M[1], &res)) != MP_OKAY) { - goto LBL_RES; - } - if ((err = redux (&res, P, &mu)) != MP_OKAY) { - goto LBL_RES; - } + /* if the bit is zero and mode == 1 then we square */ + if ((mode == 1) && (y == 0)) { + if ((err = mp_sqr(&res, &res)) != MP_OKAY) { + goto LBL_RES; + } + if ((err = redux(&res, P, &mu)) != MP_OKAY) { + goto LBL_RES; + } + continue; } - } - } - mp_exch (&res, Y); - err = MP_OKAY; -LBL_RES:mp_clear (&res); -LBL_MU:mp_clear (&mu); + /* else we add it to the window */ + bitbuf |= (y << (winsize - ++bitcpy)); + mode = 2; + + if (bitcpy == winsize) { + /* ok window is filled so square as required and multiply */ + /* square first */ + for (x = 0; x < winsize; x++) { + if ((err = mp_sqr(&res, &res)) != MP_OKAY) { + goto LBL_RES; + } + if ((err = redux(&res, P, &mu)) != MP_OKAY) { + goto LBL_RES; + } + } + + /* then multiply */ + if ((err = mp_mul(&res, &M[bitbuf], &res)) != MP_OKAY) { + goto LBL_RES; + } + if ((err = redux(&res, P, &mu)) != MP_OKAY) { + goto LBL_RES; + } + + /* empty window and reset */ + bitcpy = 0; + bitbuf = 0; + mode = 1; + } + } + + /* if bits remain then square/multiply */ + if ((mode == 2) && (bitcpy > 0)) { + /* square then multiply if the bit is set */ + for (x = 0; x < bitcpy; x++) { + if ((err = mp_sqr(&res, &res)) != MP_OKAY) { + goto LBL_RES; + } + if ((err = redux(&res, P, &mu)) != MP_OKAY) { + goto LBL_RES; + } + + bitbuf <<= 1; + if ((bitbuf & (1 << winsize)) != 0) { + /* then multiply */ + if ((err = mp_mul(&res, &M[1], &res)) != MP_OKAY) { + goto LBL_RES; + } + if ((err = redux(&res, P, &mu)) != MP_OKAY) { + goto LBL_RES; + } + } + } + } + + mp_exch(&res, Y); + err = MP_OKAY; +LBL_RES: + mp_clear(&res); +LBL_MU: + mp_clear(&mu); LBL_M: - mp_clear(&M[1]); - for (x = 1<<(winsize-1); x < (1 << winsize); x++) { - mp_clear (&M[x]); - } - return err; + mp_clear(&M[1]); + for (x = 1<<(winsize-1); x < (1 << winsize); x++) { + mp_clear(&M[x]); + } + return err; } #endif |