diff options
Diffstat (limited to 'libtommath/etc/pprime.c')
-rw-r--r-- | libtommath/etc/pprime.c | 400 |
1 files changed, 400 insertions, 0 deletions
diff --git a/libtommath/etc/pprime.c b/libtommath/etc/pprime.c new file mode 100644 index 0000000..abb3c5a --- /dev/null +++ b/libtommath/etc/pprime.c @@ -0,0 +1,400 @@ +/* Generates provable primes + * + * See http://gmail.com:8080/papers/pp.pdf for more info. + * + * Tom St Denis, tomstdenis@gmail.com, http://tom.gmail.com + */ +#include <time.h> +#include "tommath.h" + +int n_prime; +FILE *primes; + +/* fast square root */ +static mp_digit +i_sqrt (mp_word x) +{ + mp_word x1, x2; + + x2 = x; + do { + x1 = x2; + x2 = x1 - ((x1 * x1) - x) / (2 * x1); + } while (x1 != x2); + + if (x1 * x1 > x) { + --x1; + } + + return x1; +} + + +/* generates a prime digit */ +static void gen_prime (void) +{ + mp_digit r, x, y, next; + FILE *out; + + out = fopen("pprime.dat", "wb"); + + /* write first set of primes */ + r = 3; fwrite(&r, 1, sizeof(mp_digit), out); + r = 5; fwrite(&r, 1, sizeof(mp_digit), out); + r = 7; fwrite(&r, 1, sizeof(mp_digit), out); + r = 11; fwrite(&r, 1, sizeof(mp_digit), out); + r = 13; fwrite(&r, 1, sizeof(mp_digit), out); + r = 17; fwrite(&r, 1, sizeof(mp_digit), out); + r = 19; fwrite(&r, 1, sizeof(mp_digit), out); + r = 23; fwrite(&r, 1, sizeof(mp_digit), out); + r = 29; fwrite(&r, 1, sizeof(mp_digit), out); + r = 31; fwrite(&r, 1, sizeof(mp_digit), out); + + /* get square root, since if 'r' is composite its factors must be < than this */ + y = i_sqrt (r); + next = (y + 1) * (y + 1); + + for (;;) { + do { + r += 2; /* next candidate */ + r &= MP_MASK; + if (r < 31) break; + + /* update sqrt ? */ + if (next <= r) { + ++y; + next = (y + 1) * (y + 1); + } + + /* loop if divisible by 3,5,7,11,13,17,19,23,29 */ + if ((r % 3) == 0) { + x = 0; + continue; + } + if ((r % 5) == 0) { + x = 0; + continue; + } + if ((r % 7) == 0) { + x = 0; + continue; + } + if ((r % 11) == 0) { + x = 0; + continue; + } + if ((r % 13) == 0) { + x = 0; + continue; + } + if ((r % 17) == 0) { + x = 0; + continue; + } + if ((r % 19) == 0) { + x = 0; + continue; + } + if ((r % 23) == 0) { + x = 0; + continue; + } + if ((r % 29) == 0) { + x = 0; + continue; + } + + /* now check if r is divisible by x + k={1,7,11,13,17,19,23,29} */ + for (x = 30; x <= y; x += 30) { + if ((r % (x + 1)) == 0) { + x = 0; + break; + } + if ((r % (x + 7)) == 0) { + x = 0; + break; + } + if ((r % (x + 11)) == 0) { + x = 0; + break; + } + if ((r % (x + 13)) == 0) { + x = 0; + break; + } + if ((r % (x + 17)) == 0) { + x = 0; + break; + } + if ((r % (x + 19)) == 0) { + x = 0; + break; + } + if ((r % (x + 23)) == 0) { + x = 0; + break; + } + if ((r % (x + 29)) == 0) { + x = 0; + break; + } + } + } while (x == 0); + if (r > 31) { fwrite(&r, 1, sizeof(mp_digit), out); printf("%9d\r", r); fflush(stdout); } + if (r < 31) break; + } + + fclose(out); +} + +void load_tab(void) +{ + primes = fopen("pprime.dat", "rb"); + if (primes == NULL) { + gen_prime(); + primes = fopen("pprime.dat", "rb"); + } + fseek(primes, 0, SEEK_END); + n_prime = ftell(primes) / sizeof(mp_digit); +} + +mp_digit prime_digit(void) +{ + int n; + mp_digit d; + + n = abs(rand()) % n_prime; + fseek(primes, n * sizeof(mp_digit), SEEK_SET); + fread(&d, 1, sizeof(mp_digit), primes); + return d; +} + + +/* makes a prime of at least k bits */ +int +pprime (int k, int li, mp_int * p, mp_int * q) +{ + mp_int a, b, c, n, x, y, z, v; + int res, ii; + static const mp_digit bases[] = { 2, 3, 5, 7, 11, 13, 17, 19 }; + + /* single digit ? */ + if (k <= (int) DIGIT_BIT) { + mp_set (p, prime_digit ()); + return MP_OKAY; + } + + if ((res = mp_init (&c)) != MP_OKAY) { + return res; + } + + if ((res = mp_init (&v)) != MP_OKAY) { + goto LBL_C; + } + + /* product of first 50 primes */ + if ((res = + mp_read_radix (&v, + "19078266889580195013601891820992757757219839668357012055907516904309700014933909014729740190", + 10)) != MP_OKAY) { + goto LBL_V; + } + + if ((res = mp_init (&a)) != MP_OKAY) { + goto LBL_V; + } + + /* set the prime */ + mp_set (&a, prime_digit ()); + + if ((res = mp_init (&b)) != MP_OKAY) { + goto LBL_A; + } + + if ((res = mp_init (&n)) != MP_OKAY) { + goto LBL_B; + } + + if ((res = mp_init (&x)) != MP_OKAY) { + goto LBL_N; + } + + if ((res = mp_init (&y)) != MP_OKAY) { + goto LBL_X; + } + + if ((res = mp_init (&z)) != MP_OKAY) { + goto LBL_Y; + } + + /* now loop making the single digit */ + while (mp_count_bits (&a) < k) { + fprintf (stderr, "prime has %4d bits left\r", k - mp_count_bits (&a)); + fflush (stderr); + top: + mp_set (&b, prime_digit ()); + + /* now compute z = a * b * 2 */ + if ((res = mp_mul (&a, &b, &z)) != MP_OKAY) { /* z = a * b */ + goto LBL_Z; + } + + if ((res = mp_copy (&z, &c)) != MP_OKAY) { /* c = a * b */ + goto LBL_Z; + } + + if ((res = mp_mul_2 (&z, &z)) != MP_OKAY) { /* z = 2 * a * b */ + goto LBL_Z; + } + + /* n = z + 1 */ + if ((res = mp_add_d (&z, 1, &n)) != MP_OKAY) { /* n = z + 1 */ + goto LBL_Z; + } + + /* check (n, v) == 1 */ + if ((res = mp_gcd (&n, &v, &y)) != MP_OKAY) { /* y = (n, v) */ + goto LBL_Z; + } + + if (mp_cmp_d (&y, 1) != MP_EQ) + goto top; + + /* now try base x=bases[ii] */ + for (ii = 0; ii < li; ii++) { + mp_set (&x, bases[ii]); + + /* compute x^a mod n */ + if ((res = mp_exptmod (&x, &a, &n, &y)) != MP_OKAY) { /* y = x^a mod n */ + goto LBL_Z; + } + + /* if y == 1 loop */ + if (mp_cmp_d (&y, 1) == MP_EQ) + continue; + + /* now x^2a mod n */ + if ((res = mp_sqrmod (&y, &n, &y)) != MP_OKAY) { /* y = x^2a mod n */ + goto LBL_Z; + } + + if (mp_cmp_d (&y, 1) == MP_EQ) + continue; + + /* compute x^b mod n */ + if ((res = mp_exptmod (&x, &b, &n, &y)) != MP_OKAY) { /* y = x^b mod n */ + goto LBL_Z; + } + + /* if y == 1 loop */ + if (mp_cmp_d (&y, 1) == MP_EQ) + continue; + + /* now x^2b mod n */ + if ((res = mp_sqrmod (&y, &n, &y)) != MP_OKAY) { /* y = x^2b mod n */ + goto LBL_Z; + } + + if (mp_cmp_d (&y, 1) == MP_EQ) + continue; + + /* compute x^c mod n == x^ab mod n */ + if ((res = mp_exptmod (&x, &c, &n, &y)) != MP_OKAY) { /* y = x^ab mod n */ + goto LBL_Z; + } + + /* if y == 1 loop */ + if (mp_cmp_d (&y, 1) == MP_EQ) + continue; + + /* now compute (x^c mod n)^2 */ + if ((res = mp_sqrmod (&y, &n, &y)) != MP_OKAY) { /* y = x^2ab mod n */ + goto LBL_Z; + } + + /* y should be 1 */ + if (mp_cmp_d (&y, 1) != MP_EQ) + continue; + break; + } + + /* no bases worked? */ + if (ii == li) + goto top; + +{ + char buf[4096]; + + mp_toradix(&n, buf, 10); + printf("Certificate of primality for:\n%s\n\n", buf); + mp_toradix(&a, buf, 10); + printf("A == \n%s\n\n", buf); + mp_toradix(&b, buf, 10); + printf("B == \n%s\n\nG == %d\n", buf, bases[ii]); + printf("----------------------------------------------------------------\n"); +} + + /* a = n */ + mp_copy (&n, &a); + } + + /* get q to be the order of the large prime subgroup */ + mp_sub_d (&n, 1, q); + mp_div_2 (q, q); + mp_div (q, &b, q, NULL); + + mp_exch (&n, p); + + res = MP_OKAY; +LBL_Z:mp_clear (&z); +LBL_Y:mp_clear (&y); +LBL_X:mp_clear (&x); +LBL_N:mp_clear (&n); +LBL_B:mp_clear (&b); +LBL_A:mp_clear (&a); +LBL_V:mp_clear (&v); +LBL_C:mp_clear (&c); + return res; +} + + +int +main (void) +{ + mp_int p, q; + char buf[4096]; + int k, li; + clock_t t1; + + srand (time (NULL)); + load_tab(); + + printf ("Enter # of bits: \n"); + fgets (buf, sizeof (buf), stdin); + sscanf (buf, "%d", &k); + + printf ("Enter number of bases to try (1 to 8):\n"); + fgets (buf, sizeof (buf), stdin); + sscanf (buf, "%d", &li); + + + mp_init (&p); + mp_init (&q); + + t1 = clock (); + pprime (k, li, &p, &q); + t1 = clock () - t1; + + printf ("\n\nTook %ld ticks, %d bits\n", t1, mp_count_bits (&p)); + + mp_toradix (&p, buf, 10); + printf ("P == %s\n", buf); + mp_toradix (&q, buf, 10); + printf ("Q == %s\n", buf); + + return 0; +} + +/* $Source: /root/tcl/repos-to-convert/tcl/libtommath/etc/pprime.c,v $ */ +/* $Revision: 1.1.1.3 $ */ +/* $Date: 2006/12/01 00:08:28 $ */ |