-typedef unsigned short *Bignum;
-
-static unsigned short Zero[1] = { 0 };
-
-#if defined TESTMODE || defined RSADEBUG
-#ifndef DLVL
-#define DLVL 10000
-#endif
-#define debug(x) bndebug(#x,x)
-static int level = 0;
-static void bndebug(char *name, Bignum b) {
- int i;
- int w = 50-level-strlen(name)-5*b[0];
- if (level >= DLVL)
- return;
- if (w < 0) w = 0;
- dprintf("%*s%s%*s", level, "", name, w, "");
- for (i=b[0]; i>0; i--)
- dprintf(" %04x", b[i]);
- dprintf("\n");
-}
-#define dmsg(x) do {if(level<DLVL){dprintf("%*s",level,"");printf x;}} while(0)
-#define enter(x) do { dmsg(x); level += 4; } while(0)
-#define leave(x) do { level -= 4; dmsg(x); } while(0)
-#else
-#define debug(x)
-#define dmsg(x)
-#define enter(x)
-#define leave(x)
-#endif
-
-static Bignum newbn(int length) {
- Bignum b = malloc((length+1)*sizeof(unsigned short));
- if (!b)
- abort(); /* FIXME */
- b[0] = length;
- return b;
-}
-
-static void freebn(Bignum b) {
- free(b);
-}
-
-static int msb(Bignum r) {
- int i;
- int j;
- unsigned short n;
-
- for (i=r[0]; i>0; i--)
- if (r[i])
- break;
-
- j = (i-1)*16;
- n = r[i];
- if (n & 0xFF00) j += 8, n >>= 8;
- if (n & 0x00F0) j += 4, n >>= 4;
- if (n & 0x000C) j += 2, n >>= 2;
- if (n & 0x0002) j += 1, n >>= 1;
-
- return j;
-}
-
-static void add(Bignum r1, Bignum r2, Bignum result) {
- int i;
- long stuff = 0;
-
- enter((">add\n"));
- debug(r1);
- debug(r2);
-
- for (i = 1 ;; i++) {
- if (i <= r1[0])
- stuff += r1[i];
- if (i <= r2[0])
- stuff += r2[i];
- if (i <= result[0])
- result[i] = stuff & 0xFFFFU;
- if (i > r1[0] && i > r2[0] && i >= result[0])
- break;
- stuff >>= 16;
- }
-
- debug(result);
- leave(("<add\n"));
-}
-
-static void sub(Bignum r1, Bignum r2, Bignum result) {
- int i;
- long stuff = 0;
-
- enter((">sub\n"));
- debug(r1);
- debug(r2);
-
- for (i = 1 ;; i++) {
- if (i <= r1[0])
- stuff += r1[i];
- if (i <= r2[0])
- stuff -= r2[i];
- if (i <= result[0])
- result[i] = stuff & 0xFFFFU;
- if (i > r1[0] && i > r2[0] && i >= result[0])
- break;
- stuff = stuff<0 ? -1 : 0;
- }
-
- debug(result);
- leave(("<sub\n"));
-}
-
-static int ge(Bignum r1, Bignum r2) {
- int i;
-
- enter((">ge\n"));
- debug(r1);
- debug(r2);
-
- if (r1[0] < r2[0])
- i = r2[0];
- else
- i = r1[0];
-
- while (i > 0) {
- unsigned short n1 = (i > r1[0] ? 0 : r1[i]);
- unsigned short n2 = (i > r2[0] ? 0 : r2[i]);
-
- if (n1 > n2) {
- dmsg(("greater\n"));
- leave(("<ge\n"));
- return 1; /* r1 > r2 */
- } else if (n1 < n2) {
- dmsg(("less\n"));
- leave(("<ge\n"));
- return 0; /* r1 < r2 */
- }
-
- i--;
- }
-
- dmsg(("equal\n"));
- leave(("<ge\n"));
- return 1; /* r1 = r2 */
-}
-
-static void modmult(Bignum r1, Bignum r2, Bignum modulus, Bignum result) {
- Bignum temp = newbn(modulus[0]+1);
- Bignum tmp2 = newbn(modulus[0]+1);
- int i;
- int bit, bits, digit, smallbit;
-
- enter((">modmult\n"));
- debug(r1);
- debug(r2);
- debug(modulus);
-
- for (i=1; i<=result[0]; i++)
- result[i] = 0; /* result := 0 */
- for (i=1; i<=temp[0]; i++)
- temp[i] = (i > r2[0] ? 0 : r2[i]); /* temp := r2 */
-
- bits = 1+msb(r1);
-
- for (bit = 0; bit < bits; bit++) {
- digit = 1 + bit / 16;
- smallbit = bit % 16;
-
- debug(temp);
- if (digit <= r1[0] && (r1[digit] & (1<<smallbit))) {
- dmsg(("bit %d\n", bit));
- add(temp, result, tmp2);
- if (ge(tmp2, modulus))
- sub(tmp2, modulus, result);
- else
- add(tmp2, Zero, result);
- debug(result);
- }
-
- add(temp, temp, tmp2);
- if (ge(tmp2, modulus))
- sub(tmp2, modulus, temp);
- else
- add(tmp2, Zero, temp);
- }
-
- freebn(temp);
- freebn(tmp2);
-
- debug(result);
- leave(("<modmult\n"));
-}
-
-static void modpow(Bignum r1, Bignum r2, Bignum modulus, Bignum result) {
- Bignum temp = newbn(modulus[0]+1);
- Bignum tmp2 = newbn(modulus[0]+1);
- int i;
- int bit, bits, digit, smallbit;
-
- enter((">modpow\n"));
- debug(r1);
- debug(r2);
- debug(modulus);
-
- for (i=1; i<=result[0]; i++)
- result[i] = (i==1); /* result := 1 */
- for (i=1; i<=temp[0]; i++)
- temp[i] = (i > r1[0] ? 0 : r1[i]); /* temp := r1 */
-
- bits = 1+msb(r2);
-
- for (bit = 0; bit < bits; bit++) {
- digit = 1 + bit / 16;
- smallbit = bit % 16;
-
- debug(temp);
- if (digit <= r2[0] && (r2[digit] & (1<<smallbit))) {
- dmsg(("bit %d\n", bit));
- modmult(temp, result, modulus, tmp2);
- add(tmp2, Zero, result);
- debug(result);
- }
-
- modmult(temp, temp, modulus, tmp2);
- add(tmp2, Zero, temp);
- }
-
- freebn(temp);
- freebn(tmp2);
-
- debug(result);
- leave(("<modpow\n"));
-}