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Beginnings of a test suite for the bignum code. The output of

Browse Source 
testdata/bignum.py is twice the size of the rest of the PuTTY source
put together, so I'm not checking it in.

This reveals bugs in the new multiplication code, which I have yet to
fix.

[originally from svn r9097]
This commit is contained in:
Simon Tatham
2011-02-20 14:59:00 +00:00
parent b22bdb2b0d
commit 01d365b626
2 changed files with 263 additions and 0 deletions
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181
sshbn.c
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@ -247,6 +247,9 @@ static void internal_mul(const BignumInt *a, const BignumInt *b,
int midlen = botlen + 1;
BignumInt *scratch;
BignumDblInt carry;
#ifdef KARA_DEBUG
int i;
#endif
/*
* The coefficients a_1 b_1 and a_0 b_0 just avoid overlapping
@ -254,11 +257,40 @@ static void internal_mul(const BignumInt *a, const BignumInt *b,
* place.
*/
#ifdef KARA_DEBUG
printf("a1,a0 = 0x");
for (i = 0; i < len; i++) {
if (i == toplen) printf(", 0x");
printf("%0*x", BIGNUM_INT_BITS/4, a[i]);
}
printf("\n");
printf("b1,b0 = 0x");
for (i = 0; i < len; i++) {
if (i == toplen) printf(", 0x");
printf("%0*x", BIGNUM_INT_BITS/4, b[i]);
}
printf("\n");
#endif
/* a_1 b_1 */
internal_mul(a, b, c, toplen);
#ifdef KARA_DEBUG
printf("a1b1 = 0x");
for (i = 0; i < 2*toplen; i++) {
printf("%0*x", BIGNUM_INT_BITS/4, c[i]);
}
printf("\n");
#endif
/* a_0 b_0 */
internal_mul(a + toplen, b + toplen, c + 2*toplen, botlen);
#ifdef KARA_DEBUG
printf("a0b0 = 0x");
for (i = 0; i < 2*botlen; i++) {
printf("%0*x", BIGNUM_INT_BITS/4, c[2*toplen+i]);
}
printf("\n");
#endif
/*
* We must allocate scratch space for the central coefficient,
@ -281,14 +313,35 @@ static void internal_mul(const BignumInt *a, const BignumInt *b,
/* compute a_1 + a_0 */
scratch[0] = internal_add(scratch+1, a+toplen, scratch+1, botlen);
#ifdef KARA_DEBUG
printf("a1plusa0 = 0x");
for (i = 0; i < midlen; i++) {
printf("%0*x", BIGNUM_INT_BITS/4, scratch[i]);
}
printf("\n");
#endif
/* compute b_1 + b_0 */
scratch[midlen] = internal_add(scratch+midlen+1, b+toplen,
scratch+midlen+1, botlen);
#ifdef KARA_DEBUG
printf("b1plusb0 = 0x");
for (i = 0; i < midlen; i++) {
printf("%0*x", BIGNUM_INT_BITS/4, scratch[midlen+i]);
}
printf("\n");
#endif
/*
* Now we can do the third multiplication.
*/
internal_mul(scratch, scratch + midlen, scratch + 2*midlen, midlen);
#ifdef KARA_DEBUG
printf("a1plusa0timesb1plusb0 = 0x");
for (i = 0; i < 2*midlen; i++) {
printf("%0*x", BIGNUM_INT_BITS/4, scratch[2*midlen+i]);
}
printf("\n");
#endif
/*
* Now we can reuse the first half of 'scratch' to compute the
@ -300,9 +353,23 @@ static void internal_mul(const BignumInt *a, const BignumInt *b,
scratch[2*midlen - 2*toplen + j] = c[j];
scratch[1] = internal_add(scratch+2, c + 2*toplen,
scratch+2, 2*botlen);
#ifdef KARA_DEBUG
printf("a1b1plusa0b0 = 0x");
for (i = 0; i < 2*midlen; i++) {
printf("%0*x", BIGNUM_INT_BITS/4, scratch[i]);
}
printf("\n");
#endif
internal_sub(scratch + 2*midlen, scratch,
scratch + 2*midlen, 2*midlen);
#ifdef KARA_DEBUG
printf("a1b0plusa0b1 = 0x");
for (i = 0; i < 2*midlen; i++) {
printf("%0*x", BIGNUM_INT_BITS/4, scratch[2*midlen+i]);
}
printf("\n");
#endif
/*
* And now all we need to do is to add that middle coefficient
@ -320,6 +387,13 @@ static void internal_mul(const BignumInt *a, const BignumInt *b,
c[j] = (BignumInt)carry;
carry >>= BIGNUM_INT_BITS;
}
#ifdef KARA_DEBUG
printf("ab = 0x");
for (i = 0; i < 2*len; i++) {
printf("%0*x", BIGNUM_INT_BITS/4, c[i]);
}
printf("\n");
#endif
/* Free scratch. */
for (j = 0; j < 4 * midlen; j++)
@ -1531,3 +1605,110 @@ char *bignum_decimal(Bignum x)
sfree(workspace);
return ret;
}
#ifdef TESTBN
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
/*
* gcc -g -O0 -DTESTBN -o testbn sshbn.c misc.c -I unix -I charset
*/
void modalfatalbox(char *p, ...)
{
va_list ap;
fprintf(stderr, "FATAL ERROR: ");
va_start(ap, p);
vfprintf(stderr, p, ap);
va_end(ap);
fputc('\n', stderr);
exit(1);
}
#define fromxdigit(c) ( (c)>'9' ? ((c)&0xDF) - 'A' + 10 : (c) - '0' )
int main(int argc, char **argv)
{
char *buf;
int line = 0;
int passes = 0, fails = 0;
while ((buf = fgetline(stdin)) != NULL) {
int maxlen = strlen(buf);
unsigned char *data = snewn(maxlen, unsigned char);
unsigned char *ptrs[4], *q;
int ptrnum;
char *bufp = buf;
line++;
q = data;
ptrnum = 0;
while (*bufp) {
char *start, *end;
int i;
while (*bufp && !isxdigit((unsigned char)*bufp))
bufp++;
start = bufp;
if (!*bufp)
break;
while (*bufp && isxdigit((unsigned char)*bufp))
bufp++;
end = bufp;
if (ptrnum >= lenof(ptrs))
break;
ptrs[ptrnum++] = q;
for (i = -((end - start) & 1); i < end-start; i += 2) {
unsigned char val = (i < 0 ? 0 : fromxdigit(start[i]));
val = val * 16 + fromxdigit(start[i+1]);
*q++ = val;
}
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 (bignum_cmp(c, p) == 0) {
passes++;
} else {
char *as = bignum_decimal(a);
char *bs = bignum_decimal(b);
char *cs = bignum_decimal(c);
char *ps = bignum_decimal(p);
printf("%d: fail: %s * %s gave %s expected %s\n",
line, as, bs, ps, cs);
fails++;
sfree(as);
sfree(bs);
sfree(cs);
sfree(ps);
}
freebn(a);
freebn(b);
freebn(c);
freebn(p);
}
sfree(buf);
sfree(data);
}
printf("passed %d failed %d total %d\n", passes, fails, passes+fails);
return fails != 0;
}
#endif