diff --git a/src/tls/libtommath.c b/src/tls/libtommath.c index f5442ff86..b75cb9bb4 100644 --- a/src/tls/libtommath.c +++ b/src/tls/libtommath.c @@ -30,6 +30,15 @@ #define BN_S_MP_MUL_HIGH_DIGS_C /* Note: #undef in tommath_superclass.h; this * would require other than mp_reduce */ +#ifdef LTM_FAST_EXPTMOD +/* Include faster exptmod (Montgomery) at the cost of about 2.5 kB in code */ +#define BN_MP_EXPTMOD_FAST_C +#define BN_MP_MONTGOMERY_SETUP_C +#define BN_FAST_MP_MONTGOMERY_REDUCE_C +#define BN_MP_MONTGOMERY_CALC_NORMALIZATION_C +#define BN_MP_MUL_2_C +#endif /* LTM_FAST_EXPTMOD */ + /* Current uses do not require support for negative exponent in exptmod, so we * can save about 1.5 kB in leaving out invmod. */ #define LTM_NO_NEG_EXP @@ -144,6 +153,9 @@ static int mp_2expt(mp_int * a, int b); static int mp_reduce_setup(mp_int * a, mp_int * b); static int mp_reduce(mp_int * x, mp_int * m, mp_int * mu); static int mp_init_size(mp_int * a, int size); +#ifdef BN_MP_EXPTMOD_FAST_C +static int mp_exptmod_fast (mp_int * G, mp_int * X, mp_int * P, mp_int * Y, int redmode); +#endif /* BN_MP_EXPTMOD_FAST_C */ @@ -2383,3 +2395,599 @@ static int s_mp_mul_high_digs (mp_int * a, mp_int * b, mp_int * c, int digs) mp_clear (&t); return MP_OKAY; } + + +#ifdef BN_MP_MONTGOMERY_SETUP_C +/* setups the montgomery reduction stuff */ +static int +mp_montgomery_setup (mp_int * n, mp_digit * rho) +{ + mp_digit x, b; + +/* fast inversion mod 2**k + * + * Based on the fact that + * + * XA = 1 (mod 2**n) => (X(2-XA)) A = 1 (mod 2**2n) + * => 2*X*A - X*X*A*A = 1 + * => 2*(1) - (1) = 1 + */ + b = n->dp[0]; + + if ((b & 1) == 0) { + return MP_VAL; + } + + x = (((b + 2) & 4) << 1) + b; /* here x*a==1 mod 2**4 */ + x *= 2 - b * x; /* here x*a==1 mod 2**8 */ +#if !defined(MP_8BIT) + x *= 2 - b * x; /* here x*a==1 mod 2**16 */ +#endif +#if defined(MP_64BIT) || !(defined(MP_8BIT) || defined(MP_16BIT)) + x *= 2 - b * x; /* here x*a==1 mod 2**32 */ +#endif +#ifdef MP_64BIT + x *= 2 - b * x; /* here x*a==1 mod 2**64 */ +#endif + + /* rho = -1/m mod b */ + *rho = (unsigned long)(((mp_word)1 << ((mp_word) DIGIT_BIT)) - x) & MP_MASK; + + return MP_OKAY; +} +#endif + + +#ifdef BN_FAST_MP_MONTGOMERY_REDUCE_C +/* computes xR**-1 == x (mod N) via Montgomery Reduction + * + * This is an optimized implementation of montgomery_reduce + * which uses the comba method to quickly calculate the columns of the + * reduction. + * + * Based on Algorithm 14.32 on pp.601 of HAC. +*/ +int fast_mp_montgomery_reduce (mp_int * x, mp_int * n, mp_digit rho) +{ + int ix, res, olduse; + mp_word W[MP_WARRAY]; + + /* get old used count */ + olduse = x->used; + + /* grow a as required */ + if (x->alloc < n->used + 1) { + if ((res = mp_grow (x, n->used + 1)) != MP_OKAY) { + return res; + } + } + + /* first we have to get the digits of the input into + * an array of double precision words W[...] + */ + { + register mp_word *_W; + register mp_digit *tmpx; + + /* alias for the W[] array */ + _W = W; + + /* alias for the digits of x*/ + tmpx = x->dp; + + /* copy the digits of a into W[0..a->used-1] */ + for (ix = 0; ix < x->used; ix++) { + *_W++ = *tmpx++; + } + + /* zero the high words of W[a->used..m->used*2] */ + for (; ix < n->used * 2 + 1; ix++) { + *_W++ = 0; + } + } + + /* now we proceed to zero successive digits + * from the least significant upwards + */ + for (ix = 0; ix < n->used; ix++) { + /* mu = ai * m' mod b + * + * We avoid a double precision multiplication (which isn't required) + * by casting the value down to a mp_digit. Note this requires + * that W[ix-1] have the carry cleared (see after the inner loop) + */ + register mp_digit mu; + mu = (mp_digit) (((W[ix] & MP_MASK) * rho) & MP_MASK); + + /* a = a + mu * m * b**i + * + * This is computed in place and on the fly. The multiplication + * by b**i is handled by offseting which columns the results + * are added to. + * + * Note the comba method normally doesn't handle carries in the + * inner loop In this case we fix the carry from the previous + * column since the Montgomery reduction requires digits of the + * result (so far) [see above] to work. This is + * handled by fixing up one carry after the inner loop. The + * carry fixups are done in order so after these loops the + * first m->used words of W[] have the carries fixed + */ + { + register int iy; + register mp_digit *tmpn; + register mp_word *_W; + + /* alias for the digits of the modulus */ + tmpn = n->dp; + + /* Alias for the columns set by an offset of ix */ + _W = W + ix; + + /* inner loop */ + for (iy = 0; iy < n->used; iy++) { + *_W++ += ((mp_word)mu) * ((mp_word)*tmpn++); + } + } + + /* now fix carry for next digit, W[ix+1] */ + W[ix + 1] += W[ix] >> ((mp_word) DIGIT_BIT); + } + + /* now we have to propagate the carries and + * shift the words downward [all those least + * significant digits we zeroed]. + */ + { + register mp_digit *tmpx; + register mp_word *_W, *_W1; + + /* nox fix rest of carries */ + + /* alias for current word */ + _W1 = W + ix; + + /* alias for next word, where the carry goes */ + _W = W + ++ix; + + for (; ix <= n->used * 2 + 1; ix++) { + *_W++ += *_W1++ >> ((mp_word) DIGIT_BIT); + } + + /* copy out, A = A/b**n + * + * The result is A/b**n but instead of converting from an + * array of mp_word to mp_digit than calling mp_rshd + * we just copy them in the right order + */ + + /* alias for destination word */ + tmpx = x->dp; + + /* alias for shifted double precision result */ + _W = W + n->used; + + for (ix = 0; ix < n->used + 1; ix++) { + *tmpx++ = (mp_digit)(*_W++ & ((mp_word) MP_MASK)); + } + + /* zero oldused digits, if the input a was larger than + * m->used+1 we'll have to clear the digits + */ + for (; ix < olduse; ix++) { + *tmpx++ = 0; + } + } + + /* set the max used and clamp */ + x->used = n->used + 1; + mp_clamp (x); + + /* if A >= m then A = A - m */ + if (mp_cmp_mag (x, n) != MP_LT) { + return s_mp_sub (x, n, x); + } + return MP_OKAY; +} +#endif + + +#ifdef BN_MP_MUL_2_C +/* b = a*2 */ +static int mp_mul_2(mp_int * a, mp_int * b) +{ + int x, res, oldused; + + /* grow to accomodate result */ + if (b->alloc < a->used + 1) { + if ((res = mp_grow (b, a->used + 1)) != MP_OKAY) { + return res; + } + } + + oldused = b->used; + b->used = a->used; + + { + register mp_digit r, rr, *tmpa, *tmpb; + + /* alias for source */ + tmpa = a->dp; + + /* alias for dest */ + tmpb = b->dp; + + /* carry */ + r = 0; + for (x = 0; x < a->used; x++) { + + /* get what will be the *next* carry bit from the + * MSB of the current digit + */ + rr = *tmpa >> ((mp_digit)(DIGIT_BIT - 1)); + + /* now shift up this digit, add in the carry [from the previous] */ + *tmpb++ = ((*tmpa++ << ((mp_digit)1)) | r) & MP_MASK; + + /* copy the carry that would be from the source + * digit into the next iteration + */ + r = rr; + } + + /* new leading digit? */ + if (r != 0) { + /* add a MSB which is always 1 at this point */ + *tmpb = 1; + ++(b->used); + } + + /* now zero any excess digits on the destination + * that we didn't write to + */ + tmpb = b->dp + b->used; + for (x = b->used; x < oldused; x++) { + *tmpb++ = 0; + } + } + b->sign = a->sign; + return MP_OKAY; +} +#endif + + +#ifdef BN_MP_MONTGOMERY_CALC_NORMALIZATION_C +/* + * shifts with subtractions when the result is greater than b. + * + * The method is slightly modified to shift B unconditionally upto just under + * the leading bit of b. This saves alot of multiple precision shifting. + */ +static int mp_montgomery_calc_normalization (mp_int * a, mp_int * b) +{ + int x, bits, res; + + /* how many bits of last digit does b use */ + bits = mp_count_bits (b) % DIGIT_BIT; + + if (b->used > 1) { + if ((res = mp_2expt (a, (b->used - 1) * DIGIT_BIT + bits - 1)) != MP_OKAY) { + return res; + } + } else { + mp_set(a, 1); + bits = 1; + } + + + /* now compute C = A * B mod b */ + for (x = bits - 1; x < (int)DIGIT_BIT; x++) { + if ((res = mp_mul_2 (a, a)) != MP_OKAY) { + return res; + } + if (mp_cmp_mag (a, b) != MP_LT) { + if ((res = s_mp_sub (a, b, a)) != MP_OKAY) { + return res; + } + } + } + + return MP_OKAY; +} +#endif + + +#ifdef BN_MP_EXPTMOD_FAST_C +/* computes Y == G**X mod P, HAC pp.616, Algorithm 14.85 + * + * Uses a left-to-right k-ary sliding window to compute the modular exponentiation. + * The value of k changes based on the size of the exponent. + * + * Uses Montgomery or Diminished Radix reduction [whichever appropriate] + */ + +static int mp_exptmod_fast (mp_int * G, mp_int * X, mp_int * P, mp_int * Y, int redmode) +{ + mp_int M[TAB_SIZE], res; + mp_digit buf, mp; + int err, bitbuf, bitcpy, bitcnt, mode, digidx, x, y, winsize; + + /* use a pointer to the reduction algorithm. This allows us to use + * one of many reduction algorithms without modding the guts of + * the code with if statements everywhere. + */ + int (*redux)(mp_int*,mp_int*,mp_digit); + + /* 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; + } +#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]); + return err; + } + } + + /* determine and setup reduction code */ + if (redmode == 0) { +#ifdef BN_MP_MONTGOMERY_SETUP_C + /* now setup montgomery */ + if ((err = mp_montgomery_setup (P, &mp)) != MP_OKAY) { + goto LBL_M; + } +#else + err = MP_VAL; + goto LBL_M; +#endif + + /* automatically pick the comba one if available (saves quite a few calls/ifs) */ +#ifdef BN_FAST_MP_MONTGOMERY_REDUCE_C + if (((P->used * 2 + 1) < MP_WARRAY) && + P->used < (1 << ((CHAR_BIT * sizeof (mp_word)) - (2 * DIGIT_BIT)))) { + redux = fast_mp_montgomery_reduce; + } else +#endif + { +#ifdef BN_MP_MONTGOMERY_REDUCE_C + /* use slower baseline Montgomery method */ + redux = mp_montgomery_reduce; +#else + err = MP_VAL; + goto LBL_M; +#endif + } + } else if (redmode == 1) { +#if defined(BN_MP_DR_SETUP_C) && defined(BN_MP_DR_REDUCE_C) + /* setup DR reduction for moduli of the form B**k - b */ + mp_dr_setup(P, &mp); + redux = mp_dr_reduce; +#else + err = MP_VAL; + goto LBL_M; +#endif + } else { +#if defined(BN_MP_REDUCE_2K_SETUP_C) && defined(BN_MP_REDUCE_2K_C) + /* setup DR reduction for moduli of the form 2**k - b */ + if ((err = mp_reduce_2k_setup(P, &mp)) != MP_OKAY) { + goto LBL_M; + } + redux = mp_reduce_2k; +#else + err = MP_VAL; + goto LBL_M; +#endif + } + + /* setup result */ + if ((err = mp_init (&res)) != MP_OKAY) { + goto LBL_M; + } + + /* create M table + * + + * + * The first half of the table is not computed though accept for M[0] and M[1] + */ + + if (redmode == 0) { +#ifdef BN_MP_MONTGOMERY_CALC_NORMALIZATION_C + /* now we need R mod m */ + if ((err = mp_montgomery_calc_normalization (&res, P)) != MP_OKAY) { + goto LBL_RES; + } +#else + err = MP_VAL; + goto LBL_RES; +#endif + + /* now set M[1] to G * R mod m */ + if ((err = mp_mulmod (G, &res, P, &M[1])) != MP_OKAY) { + goto LBL_RES; + } + } else { + mp_set(&res, 1); + if ((err = mp_mod(G, P, &M[1])) != MP_OKAY) { + goto LBL_RES; + } + } + + /* 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_RES; + } + + for (x = 0; x < (winsize - 1); x++) { + if ((err = mp_sqr (&M[1 << (winsize - 1)], &M[1 << (winsize - 1)])) != MP_OKAY) { + goto LBL_RES; + } + if ((err = redux (&M[1 << (winsize - 1)], P, mp)) != MP_OKAY) { + goto LBL_RES; + } + } + + /* create upper table */ + 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_RES; + } + if ((err = redux (&M[x], P, mp)) != MP_OKAY) { + goto LBL_RES; + } + } + + /* 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 so break */ + if (digidx == -1) { + break; + } + /* read next digit and reset bitcnt */ + buf = X->dp[digidx--]; + bitcnt = (int)DIGIT_BIT; + } + + /* grab the next msb from the exponent */ + y = (mp_digit)(buf >> (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; + } + if ((err = redux (&res, P, mp)) != MP_OKAY) { + goto LBL_RES; + } + 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, mp)) != 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, mp)) != 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, mp)) != MP_OKAY) { + goto LBL_RES; + } + + /* get next bit of the window */ + 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, mp)) != MP_OKAY) { + goto LBL_RES; + } + } + } + } + + if (redmode == 0) { + /* fixup result if Montgomery reduction is used + * recall that any value in a Montgomery system is + * actually multiplied by R mod n. So we have + * to reduce one more time to cancel out the factor + * of R. + */ + if ((err = redux(&res, P, mp)) != MP_OKAY) { + goto LBL_RES; + } + } + + /* swap res with Y */ + mp_exch (&res, Y); + err = MP_OKAY; +LBL_RES:mp_clear (&res); +LBL_M: + mp_clear(&M[1]); + for (x = 1<<(winsize-1); x < (1 << winsize); x++) { + mp_clear (&M[x]); + } + return err; +} +#endif diff --git a/wpa_supplicant/Makefile b/wpa_supplicant/Makefile index f185b590e..d1c6a0883 100644 --- a/wpa_supplicant/Makefile +++ b/wpa_supplicant/Makefile @@ -621,6 +621,9 @@ CFLAGS += -DCONFIG_TLS_INTERNAL_CLIENT ifeq ($(CONFIG_CRYPTO), internal) ifdef CONFIG_INTERNAL_LIBTOMMATH CFLAGS += -DCONFIG_INTERNAL_LIBTOMMATH +ifdef CONFIG_INTERNAL_LIBTOMMATH_FAST_EXPTMOD +CFLAGS += -DLTM_FAST_EXPTMOD +endif else LIBS += -ltommath LIBS_p += -ltommath diff --git a/wpa_supplicant/defconfig b/wpa_supplicant/defconfig index 8b89ccb99..80e5261bb 100644 --- a/wpa_supplicant/defconfig +++ b/wpa_supplicant/defconfig @@ -307,6 +307,9 @@ CONFIG_PEERKEY=y #LIBS += -L$(LTM_PATH) #LIBS_p += -L$(LTM_PATH) #endif +# Add a cost of about 2.5 kB of additional cost, the internal LibTomMath can be +# configured to include fast exptmod routine to speed up DH and RSA. +#CONFIG_INTERNAL_LIBTOMMATH_FAST_EXPTMOD=y # Include NDIS event processing through WMI into wpa_supplicant/wpasvc. # This is only for Windows builds and requires WMI-related header files and