X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/134a1ab5f9b5976073bfb9a5f723b945ca06533a..88ea89339783ee587180b645981967f6cb8bcd20:/sshbn.c diff --git a/sshbn.c b/sshbn.c index cae1bd9e..24f3ca6b 100644 --- a/sshbn.c +++ b/sshbn.c @@ -148,7 +148,7 @@ void freebn(Bignum b) /* * Burn the evidence, just in case. */ - memset(b, 0, sizeof(b[0]) * (b[0] + 1)); + smemclr(b, sizeof(b[0]) * (b[0] + 1)); sfree(b); } @@ -201,15 +201,28 @@ static void internal_sub(const BignumInt *a, const BignumInt *b, * Compute c = a * b. * Input is in the first len words of a and b. * Result is returned in the first 2*len words of c. + * + * 'scratch' must point to an array of BignumInt of size at least + * mul_compute_scratch(len). (This covers the needs of internal_mul + * and all its recursive calls to itself.) */ #define KARATSUBA_THRESHOLD 50 +static int mul_compute_scratch(int len) +{ + int ret = 0; + while (len > KARATSUBA_THRESHOLD) { + int toplen = len/2, botlen = len - toplen; /* botlen is the bigger */ + int midlen = botlen + 1; + ret += 4*midlen; + len = midlen; + } + return ret; +} static void internal_mul(const BignumInt *a, const BignumInt *b, - BignumInt *c, int len) + BignumInt *c, int len, BignumInt *scratch) { - int i, j; - BignumDblInt t; - if (len > KARATSUBA_THRESHOLD) { + int i; /* * Karatsuba divide-and-conquer algorithm. Cut each input in @@ -245,7 +258,6 @@ static void internal_mul(const BignumInt *a, const BignumInt *b, int toplen = len/2, botlen = len - toplen; /* botlen is the bigger */ int midlen = botlen + 1; - BignumInt *scratch; BignumDblInt carry; #ifdef KARA_DEBUG int i; @@ -273,7 +285,7 @@ static void internal_mul(const BignumInt *a, const BignumInt *b, #endif /* a_1 b_1 */ - internal_mul(a, b, c, toplen); + internal_mul(a, b, c, toplen, scratch); #ifdef KARA_DEBUG printf("a1b1 = 0x"); for (i = 0; i < 2*toplen; i++) { @@ -283,7 +295,7 @@ static void internal_mul(const BignumInt *a, const BignumInt *b, #endif /* a_0 b_0 */ - internal_mul(a + toplen, b + toplen, c + 2*toplen, botlen); + internal_mul(a + toplen, b + toplen, c + 2*toplen, botlen, scratch); #ifdef KARA_DEBUG printf("a0b0 = 0x"); for (i = 0; i < 2*botlen; i++) { @@ -292,23 +304,14 @@ static void internal_mul(const BignumInt *a, const BignumInt *b, printf("\n"); #endif - /* - * We must allocate scratch space for the central coefficient, - * and also for the two input values that we multiply when - * computing it. Since either or both may carry into the - * (botlen+1)th word, we must use a slightly longer length - * 'midlen'. - */ - scratch = snewn(4 * midlen, BignumInt); - /* Zero padding. midlen exceeds toplen by at most 2, so just * zero the first two words of each input and the rest will be * copied over. */ scratch[0] = scratch[1] = scratch[midlen] = scratch[midlen+1] = 0; - for (j = 0; j < toplen; j++) { - scratch[midlen - toplen + j] = a[j]; /* a_1 */ - scratch[2*midlen - toplen + j] = b[j]; /* b_1 */ + for (i = 0; i < toplen; i++) { + scratch[midlen - toplen + i] = a[i]; /* a_1 */ + scratch[2*midlen - toplen + i] = b[i]; /* b_1 */ } /* compute a_1 + a_0 */ @@ -334,7 +337,8 @@ static void internal_mul(const BignumInt *a, const BignumInt *b, /* * Now we can do the third multiplication. */ - internal_mul(scratch, scratch + midlen, scratch + 2*midlen, midlen); + internal_mul(scratch, scratch + midlen, scratch + 2*midlen, midlen, + scratch + 4*midlen); #ifdef KARA_DEBUG printf("a1plusa0timesb1plusb0 = 0x"); for (i = 0; i < 2*midlen; i++) { @@ -349,8 +353,8 @@ static void internal_mul(const BignumInt *a, const BignumInt *b, * product to obtain the middle one. */ scratch[0] = scratch[1] = scratch[2] = scratch[3] = 0; - for (j = 0; j < 2*toplen; j++) - scratch[2*midlen - 2*toplen + j] = c[j]; + for (i = 0; i < 2*toplen; i++) + scratch[2*midlen - 2*toplen + i] = c[i]; scratch[1] = internal_add(scratch+2, c + 2*toplen, scratch+2, 2*botlen); #ifdef KARA_DEBUG @@ -380,13 +384,13 @@ static void internal_mul(const BignumInt *a, const BignumInt *b, carry = internal_add(c + 2*len - botlen - 2*midlen, scratch + 2*midlen, c + 2*len - botlen - 2*midlen, 2*midlen); - j = 2*len - botlen - 2*midlen - 1; + i = 2*len - botlen - 2*midlen - 1; while (carry) { - assert(j >= 0); - carry += c[j]; - c[j] = (BignumInt)carry; + assert(i >= 0); + carry += c[i]; + c[i] = (BignumInt)carry; carry >>= BIGNUM_INT_BITS; - j--; + i--; } #ifdef KARA_DEBUG printf("ab = 0x"); @@ -396,29 +400,28 @@ static void internal_mul(const BignumInt *a, const BignumInt *b, printf("\n"); #endif - /* Free scratch. */ - for (j = 0; j < 4 * midlen; j++) - scratch[j] = 0; - sfree(scratch); - } else { + int i; + BignumInt carry; + BignumDblInt t; + const BignumInt *ap, *bp; + BignumInt *cp, *cps; /* * Multiply in the ordinary O(N^2) way. */ - for (j = 0; j < 2 * len; j++) - c[j] = 0; + for (i = 0; i < 2 * len; i++) + c[i] = 0; - for (i = len - 1; i >= 0; i--) { - t = 0; - for (j = len - 1; j >= 0; j--) { - t += MUL_WORD(a[i], (BignumDblInt) b[j]); - t += (BignumDblInt) c[i + j + 1]; - c[i + j + 1] = (BignumInt) t; - t = t >> BIGNUM_INT_BITS; + for (cps = c + 2*len, ap = a + len; ap-- > a; cps--) { + carry = 0; + for (cp = cps, bp = b + len; cp--, bp-- > b ;) { + t = (MUL_WORD(*ap, *bp) + carry) + *cp; + *cp = (BignumInt) t; + carry = (BignumInt)(t >> BIGNUM_INT_BITS); } - c[i] = (BignumInt) t; + *cp = carry; } } } @@ -429,12 +432,10 @@ static void internal_mul(const BignumInt *a, const BignumInt *b, * (everything above that is thrown away). */ static void internal_mul_low(const BignumInt *a, const BignumInt *b, - BignumInt *c, int len) + BignumInt *c, int len, BignumInt *scratch) { - int i, j; - BignumDblInt t; - if (len > KARATSUBA_THRESHOLD) { + int i; /* * Karatsuba-aware version of internal_mul_low. As before, we @@ -469,29 +470,30 @@ static void internal_mul_low(const BignumInt *a, const BignumInt *b, */ int toplen = len/2, botlen = len - toplen; /* botlen is the bigger */ - BignumInt *scratch; /* - * Allocate scratch space for the various bits and pieces - * we're going to be adding together. We need botlen*2 words - * for a_0 b_0 (though we may end up throwing away its topmost - * word), and toplen words for each of a_1 b_0 and a_0 b_1. - * That adds up to exactly 2*len. + * Scratch space for the various bits and pieces we're going + * to be adding together: we need botlen*2 words for a_0 b_0 + * (though we may end up throwing away its topmost word), and + * toplen words for each of a_1 b_0 and a_0 b_1. That adds up + * to exactly 2*len. */ - scratch = snewn(len*2, BignumInt); /* a_0 b_0 */ - internal_mul(a + toplen, b + toplen, scratch + 2*toplen, botlen); + internal_mul(a + toplen, b + toplen, scratch + 2*toplen, botlen, + scratch + 2*len); /* a_1 b_0 */ - internal_mul_low(a, b + len - toplen, scratch + toplen, toplen); + internal_mul_low(a, b + len - toplen, scratch + toplen, toplen, + scratch + 2*len); /* a_0 b_1 */ - internal_mul_low(a + len - toplen, b, scratch, toplen); + internal_mul_low(a + len - toplen, b, scratch, toplen, + scratch + 2*len); /* Copy the bottom half of the big coefficient into place */ - for (j = 0; j < botlen; j++) - c[toplen + j] = scratch[2*toplen + botlen + j]; + for (i = 0; i < botlen; i++) + c[toplen + i] = scratch[2*toplen + botlen + i]; /* Add the two small coefficients, throwing away the returned carry */ internal_add(scratch, scratch + toplen, scratch, toplen); @@ -500,26 +502,28 @@ static void internal_mul_low(const BignumInt *a, const BignumInt *b, internal_add(scratch, scratch + 2*toplen + botlen - toplen, c, toplen); - /* Free scratch. */ - for (j = 0; j < len*2; j++) - scratch[j] = 0; - sfree(scratch); - } else { + int i; + BignumInt carry; + BignumDblInt t; + const BignumInt *ap, *bp; + BignumInt *cp, *cps; - for (j = 0; j < len; j++) - c[j] = 0; + /* + * Multiply in the ordinary O(N^2) way. + */ - for (i = len - 1; i >= 0; i--) { - t = 0; - for (j = len - 1; j >= len - i - 1; j--) { - t += MUL_WORD(a[i], (BignumDblInt) b[j]); - t += (BignumDblInt) c[i + j + 1 - len]; - c[i + j + 1 - len] = (BignumInt) t; - t = t >> BIGNUM_INT_BITS; + for (i = 0; i < len; i++) + c[i] = 0; + + for (cps = c + len, ap = a + len; ap-- > a; cps--) { + carry = 0; + for (cp = cps, bp = b + len; bp--, cp-- > c ;) { + t = (MUL_WORD(*ap, *bp) + carry) + *cp; + *cp = (BignumInt) t; + carry = (BignumInt)(t >> BIGNUM_INT_BITS); } } - } } @@ -534,8 +538,8 @@ static void internal_mul_low(const BignumInt *a, const BignumInt *b, * each, containing respectively n and the multiplicative inverse of * -n mod r. * - * 'tmp' is an array of at least '3*len' BignumInts used as scratch - * space. + * 'tmp' is an array of BignumInt used as scratch space, of length at + * least 3*len + mul_compute_scratch(len). */ static void monty_reduce(BignumInt *x, const BignumInt *n, const BignumInt *mninv, BignumInt *tmp, int len) @@ -548,7 +552,7 @@ static void monty_reduce(BignumInt *x, const BignumInt *n, * that mn is congruent to -x mod r. Hence, mn+x is an exact * multiple of r, and is also (obviously) congruent to x mod n. */ - internal_mul_low(x + len, mninv, tmp, len); + internal_mul_low(x + len, mninv, tmp, len, tmp + 3*len); /* * Compute t = (mn+x)/r in ordinary, non-modular, integer @@ -559,7 +563,7 @@ static void monty_reduce(BignumInt *x, const BignumInt *n, * significant half of the 'x' array, so then we must shift it * down. */ - internal_mul(tmp, n, tmp+len, len); + internal_mul(tmp, n, tmp+len, len, tmp + 3*len); carry = internal_add(x, tmp+len, x, 2*len); for (i = 0; i < len; i++) x[len + i] = x[i], x[i] = 0; @@ -705,14 +709,14 @@ static void internal_mod(BignumInt *a, int alen, } /* - * Compute (base ^ exp) % mod. Uses the Montgomery multiplication - * technique. + * Compute (base ^ exp) % mod, the pedestrian way. */ -Bignum modpow(Bignum base_in, Bignum exp, Bignum mod) +Bignum modpow_simple(Bignum base_in, Bignum exp, Bignum mod) { - BignumInt *a, *b, *x, *n, *mninv, *tmp; - int len, i, j; - Bignum base, base2, r, rn, inv, result; + BignumInt *a, *b, *n, *m, *scratch; + int mshift; + int mlen, scratchlen, i, j; + Bignum base, result; /* * The most significant word of mod needs to be non-zero. It @@ -726,11 +730,140 @@ Bignum modpow(Bignum base_in, Bignum exp, Bignum mod) */ base = bigmod(base_in, mod); + /* Allocate m of size mlen, copy mod to m */ + /* We use big endian internally */ + mlen = mod[0]; + m = snewn(mlen, BignumInt); + for (j = 0; j < mlen; j++) + m[j] = mod[mod[0] - j]; + + /* Shift m left to make msb bit set */ + for (mshift = 0; mshift < BIGNUM_INT_BITS-1; mshift++) + if ((m[0] << mshift) & BIGNUM_TOP_BIT) + break; + if (mshift) { + for (i = 0; i < mlen - 1; i++) + m[i] = (m[i] << mshift) | (m[i + 1] >> (BIGNUM_INT_BITS - mshift)); + m[mlen - 1] = m[mlen - 1] << mshift; + } + + /* Allocate n of size mlen, copy base to n */ + n = snewn(mlen, BignumInt); + i = mlen - base[0]; + for (j = 0; j < i; j++) + n[j] = 0; + for (j = 0; j < (int)base[0]; j++) + n[i + j] = base[base[0] - j]; + + /* Allocate a and b of size 2*mlen. Set a = 1 */ + a = snewn(2 * mlen, BignumInt); + b = snewn(2 * mlen, BignumInt); + for (i = 0; i < 2 * mlen; i++) + a[i] = 0; + a[2 * mlen - 1] = 1; + + /* Scratch space for multiplies */ + scratchlen = mul_compute_scratch(mlen); + scratch = snewn(scratchlen, BignumInt); + + /* Skip leading zero bits of exp. */ + i = 0; + j = BIGNUM_INT_BITS-1; + while (i < (int)exp[0] && (exp[exp[0] - i] & (1 << j)) == 0) { + j--; + if (j < 0) { + i++; + j = BIGNUM_INT_BITS-1; + } + } + + /* Main computation */ + while (i < (int)exp[0]) { + while (j >= 0) { + internal_mul(a + mlen, a + mlen, b, mlen, scratch); + internal_mod(b, mlen * 2, m, mlen, NULL, 0); + if ((exp[exp[0] - i] & (1 << j)) != 0) { + internal_mul(b + mlen, n, a, mlen, scratch); + internal_mod(a, mlen * 2, m, mlen, NULL, 0); + } else { + BignumInt *t; + t = a; + a = b; + b = t; + } + j--; + } + i++; + j = BIGNUM_INT_BITS-1; + } + + /* Fixup result in case the modulus was shifted */ + if (mshift) { + for (i = mlen - 1; i < 2 * mlen - 1; i++) + a[i] = (a[i] << mshift) | (a[i + 1] >> (BIGNUM_INT_BITS - mshift)); + a[2 * mlen - 1] = a[2 * mlen - 1] << mshift; + internal_mod(a, mlen * 2, m, mlen, NULL, 0); + for (i = 2 * mlen - 1; i >= mlen; i--) + a[i] = (a[i] >> mshift) | (a[i - 1] << (BIGNUM_INT_BITS - mshift)); + } + + /* Copy result to buffer */ + result = newbn(mod[0]); + for (i = 0; i < mlen; i++) + result[result[0] - i] = a[i + mlen]; + while (result[0] > 1 && result[result[0]] == 0) + result[0]--; + + /* Free temporary arrays */ + for (i = 0; i < 2 * mlen; i++) + a[i] = 0; + sfree(a); + for (i = 0; i < scratchlen; i++) + scratch[i] = 0; + sfree(scratch); + for (i = 0; i < 2 * mlen; i++) + b[i] = 0; + sfree(b); + for (i = 0; i < mlen; i++) + m[i] = 0; + sfree(m); + for (i = 0; i < mlen; i++) + n[i] = 0; + sfree(n); + + freebn(base); + + return result; +} + +/* + * Compute (base ^ exp) % mod. Uses the Montgomery multiplication + * technique where possible, falling back to modpow_simple otherwise. + */ +Bignum modpow(Bignum base_in, Bignum exp, Bignum mod) +{ + BignumInt *a, *b, *x, *n, *mninv, *scratch; + int len, scratchlen, i, j; + Bignum base, base2, r, rn, inv, result; + + /* + * The most significant word of mod needs to be non-zero. It + * should already be, but let's make sure. + */ + assert(mod[mod[0]] != 0); + /* * mod had better be odd, or we can't do Montgomery multiplication * using a power of two at all. */ - assert(mod[1] & 1); + if (!(mod[1] & 1)) + return modpow_simple(base_in, exp, mod); + + /* + * Make sure the base is smaller than the modulus, by reducing + * it modulo the modulus if not. + */ + base = bigmod(base_in, mod); /* * Compute the inverse of n mod r, for monty_reduce. (In fact we @@ -764,7 +897,7 @@ Bignum modpow(Bignum base_in, Bignum exp, Bignum mod) mninv = snewn(len, BignumInt); for (j = 0; j < len; j++) - mninv[len - 1 - j] = (j < inv[0] ? inv[j + 1] : 0); + mninv[len - 1 - j] = (j < (int)inv[0] ? inv[j + 1] : 0); freebn(inv); /* we don't need this copy of it any more */ /* Now negate mninv mod r, so it's the inverse of -n rather than +n. */ x = snewn(len, BignumInt); @@ -774,16 +907,18 @@ Bignum modpow(Bignum base_in, Bignum exp, Bignum mod) /* x = snewn(len, BignumInt); */ /* already done above */ for (j = 0; j < len; j++) - x[len - 1 - j] = (j < base[0] ? base[j + 1] : 0); + x[len - 1 - j] = (j < (int)base[0] ? base[j + 1] : 0); freebn(base); /* we don't need this copy of it any more */ a = snewn(2*len, BignumInt); b = snewn(2*len, BignumInt); for (j = 0; j < len; j++) - a[2*len - 1 - j] = (j < rn[0] ? rn[j + 1] : 0); + a[2*len - 1 - j] = (j < (int)rn[0] ? rn[j + 1] : 0); freebn(rn); - tmp = snewn(3*len, BignumInt); + /* Scratch space for multiplies */ + scratchlen = 3*len + mul_compute_scratch(len); + scratch = snewn(scratchlen, BignumInt); /* Skip leading zero bits of exp. */ i = 0; @@ -799,11 +934,11 @@ Bignum modpow(Bignum base_in, Bignum exp, Bignum mod) /* Main computation */ while (i < (int)exp[0]) { while (j >= 0) { - internal_mul(a + len, a + len, b, len); - monty_reduce(b, n, mninv, tmp, len); + internal_mul(a + len, a + len, b, len, scratch); + monty_reduce(b, n, mninv, scratch, len); if ((exp[exp[0] - i] & (1 << j)) != 0) { - internal_mul(b + len, x, a, len); - monty_reduce(a, n, mninv, tmp, len); + internal_mul(b + len, x, a, len, scratch); + monty_reduce(a, n, mninv, scratch, len); } else { BignumInt *t; t = a; @@ -820,7 +955,7 @@ Bignum modpow(Bignum base_in, Bignum exp, Bignum mod) * Final monty_reduce to get back from the adjusted Montgomery * representation. */ - monty_reduce(a, n, mninv, tmp, len); + monty_reduce(a, n, mninv, scratch, len); /* Copy result to buffer */ result = newbn(mod[0]); @@ -830,9 +965,9 @@ Bignum modpow(Bignum base_in, Bignum exp, Bignum mod) result[0]--; /* Free temporary arrays */ - for (i = 0; i < 3 * len; i++) - tmp[i] = 0; - sfree(tmp); + for (i = 0; i < scratchlen; i++) + scratch[i] = 0; + sfree(scratch); for (i = 0; i < 2 * len; i++) a[i] = 0; sfree(a); @@ -859,8 +994,8 @@ Bignum modpow(Bignum base_in, Bignum exp, Bignum mod) */ Bignum modmul(Bignum p, Bignum q, Bignum mod) { - BignumInt *a, *n, *m, *o; - int mshift; + BignumInt *a, *n, *m, *o, *scratch; + int mshift, scratchlen; int pqlen, mlen, rlen, i, j; Bignum result; @@ -902,8 +1037,12 @@ Bignum modmul(Bignum p, Bignum q, Bignum mod) /* Allocate a of size 2*pqlen for result */ a = snewn(2 * pqlen, BignumInt); + /* Scratch space for multiplies */ + scratchlen = mul_compute_scratch(pqlen); + scratch = snewn(scratchlen, BignumInt); + /* Main computation */ - internal_mul(n, o, a, pqlen); + internal_mul(n, o, a, pqlen, scratch); internal_mod(a, pqlen * 2, m, mlen, NULL, 0); /* Fixup result in case the modulus was shifted */ @@ -925,6 +1064,9 @@ Bignum modmul(Bignum p, Bignum q, Bignum mod) result[0]--; /* Free temporary arrays */ + for (i = 0; i < scratchlen; i++) + scratch[i] = 0; + sfree(scratch); for (i = 0; i < 2 * pqlen; i++) a[i] = 0; sfree(a); @@ -1213,18 +1355,21 @@ Bignum bigmuladd(Bignum a, Bignum b, Bignum addend) int alen = a[0], blen = b[0]; int mlen = (alen > blen ? alen : blen); int rlen, i, maxspot; + int wslen; BignumInt *workspace; Bignum ret; - /* mlen space for a, mlen space for b, 2*mlen for result */ - workspace = snewn(mlen * 4, BignumInt); + /* mlen space for a, mlen space for b, 2*mlen for result, + * plus scratch space for multiplication */ + wslen = mlen * 4 + mul_compute_scratch(mlen); + workspace = snewn(wslen, BignumInt); for (i = 0; i < mlen; i++) { workspace[0 * mlen + i] = (mlen - i <= (int)a[0] ? a[mlen - i] : 0); workspace[1 * mlen + i] = (mlen - i <= (int)b[0] ? b[mlen - i] : 0); } internal_mul(workspace + 0 * mlen, workspace + 1 * mlen, - workspace + 2 * mlen, mlen); + workspace + 2 * mlen, mlen, workspace + 4 * mlen); /* now just copy the result back */ rlen = alen + blen + 1; @@ -1253,6 +1398,8 @@ Bignum bigmuladd(Bignum a, Bignum b, Bignum addend) } ret[0] = maxspot; + for (i = 0; i < wslen; i++) + workspace[i] = 0; sfree(workspace); return ret; } @@ -1614,7 +1761,10 @@ char *bignum_decimal(Bignum x) #include /* - * gcc -g -O0 -DTESTBN -o testbn sshbn.c misc.c -I unix -I charset + * gcc -Wall -g -O0 -DTESTBN -o testbn sshbn.c misc.c conf.c tree234.c unix/uxmisc.c -I. -I unix -I charset + * + * Then feed to this program's standard input the output of + * testdata/bignum.py . */ void modalfatalbox(char *p, ...) @@ -1639,7 +1789,7 @@ int main(int argc, char **argv) while ((buf = fgetline(stdin)) != NULL) { int maxlen = strlen(buf); unsigned char *data = snewn(maxlen, unsigned char); - unsigned char *ptrs[4], *q; + unsigned char *ptrs[5], *q; int ptrnum; char *bufp = buf; @@ -1648,6 +1798,11 @@ int main(int argc, char **argv) q = data; ptrnum = 0; + while (*bufp && !isspace((unsigned char)*bufp)) + bufp++; + if (bufp) + *bufp++ = '\0'; + while (*bufp) { char *start, *end; int i; @@ -1676,11 +1831,17 @@ int main(int argc, char **argv) ptrs[ptrnum] = q; } - if (ptrnum == 3) { - Bignum a = bignum_from_bytes(ptrs[0], ptrs[1]-ptrs[0]); - Bignum b = bignum_from_bytes(ptrs[1], ptrs[2]-ptrs[1]); - Bignum c = bignum_from_bytes(ptrs[2], ptrs[3]-ptrs[2]); - Bignum p = bigmul(a, b); + if (!strcmp(buf, "mul")) { + Bignum a, b, c, p; + + if (ptrnum != 3) { + printf("%d: mul with %d parameters, expected 3\n", line, ptrnum); + exit(1); + } + a = bignum_from_bytes(ptrs[0], ptrs[1]-ptrs[0]); + b = bignum_from_bytes(ptrs[1], ptrs[2]-ptrs[1]); + c = bignum_from_bytes(ptrs[2], ptrs[3]-ptrs[2]); + p = bigmul(a, b); if (bignum_cmp(c, p) == 0) { passes++; @@ -1703,7 +1864,49 @@ int main(int argc, char **argv) freebn(b); freebn(c); freebn(p); + } else if (!strcmp(buf, "pow")) { + Bignum base, expt, modulus, expected, answer; + + if (ptrnum != 4) { + printf("%d: mul with %d parameters, expected 4\n", line, ptrnum); + exit(1); + } + + base = bignum_from_bytes(ptrs[0], ptrs[1]-ptrs[0]); + expt = bignum_from_bytes(ptrs[1], ptrs[2]-ptrs[1]); + modulus = bignum_from_bytes(ptrs[2], ptrs[3]-ptrs[2]); + expected = bignum_from_bytes(ptrs[3], ptrs[4]-ptrs[3]); + answer = modpow(base, expt, modulus); + + if (bignum_cmp(expected, answer) == 0) { + passes++; + } else { + char *as = bignum_decimal(base); + char *bs = bignum_decimal(expt); + char *cs = bignum_decimal(modulus); + char *ds = bignum_decimal(answer); + char *ps = bignum_decimal(expected); + + printf("%d: fail: %s ^ %s mod %s gave %s expected %s\n", + line, as, bs, cs, ds, ps); + fails++; + + sfree(as); + sfree(bs); + sfree(cs); + sfree(ds); + sfree(ps); + } + freebn(base); + freebn(expt); + freebn(modulus); + freebn(expected); + freebn(answer); + } else { + printf("%d: unrecognised test keyword: '%s'\n", line, buf); + exit(1); } + sfree(buf); sfree(data); }