int rand_prime(mp_int *N, long len, prng_state *prng, int wprng)
{
unsigned char buf[260];
int err, step, ormask;
_ARGCHK(N != NULL);
/* pass a negative size if you want a prime congruent to 3 mod 4 */
if (len < 0) {
step = 4;
ormask = 3;
len = -len;
} else {
step = 2;
ormask = 1;
}
/* allow sizes between 2 and 256 bytes for a prime size */
if (len < 2 || len > 256) {
return CRYPT_INVALID_PRIME_SIZE;
}
/* valid PRNG? */
if ((err = prng_is_valid(wprng)) != CRYPT_OK) {
return err;
}
/* read the prng */
if (prng_descriptor[wprng].read(buf+2, (unsigned long)len, prng) != (unsigned long)len) {
return CRYPT_ERROR_READPRNG;
}
/* set sign byte to zero */
buf[0] = (unsigned char)0;
/* Set the top byte to 0x01 which makes the number a len*8 bit number */
buf[1] = (unsigned char)0x01;
/* set the LSB to the desired settings
* (1 for any prime, 3 for primes congruent to 3 mod 4)
*/
buf[len+1] |= (unsigned char)ormask;
/* read the number in */
if (mp_read_raw(N, buf, 2+len) != MP_OKAY) {
return CRYPT_MEM;
}
/* add the step size to it while N is not prime */
if ((err = next_prime(N, step)) != CRYPT_OK) {
return err;
}
#ifdef CLEAN_STACK
zeromem(buf, sizeof(buf));
#endif
return CRYPT_OK;
}
void bbs_srand(unsigned char *data, int len)
{
if((bbs_init & SEED) == 0) {
mp_init(&bbs_state);
bbs_init |= SEED;
}
mp_read_raw(&bbs_state, (char *)data, len);
} /* end bbs_srand() */
void rand_num2(mp_int *a)
{
int n, size;
unsigned char buf[2048];
size = 10 + ((fgetc(rng)<<8) + fgetc(rng)) % 101;
buf[0] = (fgetc(rng)&1)?1:0;
fread(buf+1, 1, size, rng);
while (buf[1] == 0) buf[1] = fgetc(rng);
mp_read_raw(a, buf, 1+size);
}
/* 1-256 bit numbers (to test things like exptmod) */
void rand_num2(mp_int *a)
{
int n, size;
unsigned char buf[2048];
size = 1 + ((fgetc(rng)<<8) + fgetc(rng)) % (FP_MAX_SIZE/16 - DIGIT_BIT/2);
buf[0] = (fgetc(rng)&1)?1:0;
fread(buf+1, 1, size, rng);
while (buf[1] == 0) buf[1] = fgetc(rng);
mp_read_raw(a, buf, 1+size);
}
void rand_num2(mp_int *a)
{
int size;
unsigned char buf[2048];
size_t sz;
size = 10 + ((getRandChar()<<8) + getRandChar()) % 101;
buf[0] = (getRandChar()&1)?1:0;
#ifdef LTM_MTEST_REAL_RAND
sz = fread(buf+1, 1, size, rng);
#else
sz = 1;
while (sz < (unsigned)size) {
buf[sz] = getRandChar();
++sz;
}
#endif
if (sz != (unsigned)size) {
fprintf(stderr, "\nWarning: fread failed\n\n");
}
while (buf[1] == 0) buf[1] = getRandChar();
mp_read_raw(a, buf, 1+size);
}
int main(int argc, char *argv[])
{
unsigned char *raw;
char *out;
unsigned long nTries;
int rawlen, bits, outlen, ngen, ix, jx;
int g_strong = 0;
mp_int testval;
mp_err res;
clock_t start, end;
/* We'll just use the C library's rand() for now, although this
won't be good enough for cryptographic purposes */
if((out = PR_GetEnvSecure("SEED")) == NULL) {
srand((unsigned int)time(NULL));
} else {
srand((unsigned int)atoi(out));
}
if(argc < 2) {
fprintf(stderr, "Usage: %s <bits> [<count> [strong]]\n", argv[0]);
return 1;
}
if((bits = abs(atoi(argv[1]))) < CHAR_BIT) {
fprintf(stderr, "%s: please request at least %d bits.\n",
argv[0], CHAR_BIT);
return 1;
}
/* If optional third argument is given, use that as the number of
primes to generate; otherwise generate one prime only.
*/
if(argc < 3) {
ngen = 1;
} else {
ngen = abs(atoi(argv[2]));
}
/* If fourth argument is given, and is the word "strong", we'll
generate strong (Sophie Germain) primes.
*/
if(argc > 3 && strcmp(argv[3], "strong") == 0)
g_strong = 1;
/* testval - candidate being tested; nTries - number tried so far */
if ((res = mp_init(&testval)) != MP_OKAY) {
fprintf(stderr, "%s: error: %s\n", argv[0], mp_strerror(res));
return 1;
}
if(g_strong) {
printf("Requested %d strong prime value(s) of %d bits.\n",
ngen, bits);
} else {
printf("Requested %d prime value(s) of %d bits.\n", ngen, bits);
}
rawlen = (bits / CHAR_BIT) + ((bits % CHAR_BIT) ? 1 : 0) + 1;
if((raw = calloc(rawlen, sizeof(unsigned char))) == NULL) {
fprintf(stderr, "%s: out of memory, sorry.\n", argv[0]);
return 1;
}
/* This loop is one for each prime we need to generate */
for(jx = 0; jx < ngen; jx++) {
raw[0] = 0; /* sign is positive */
/* Pack the initializer with random bytes */
for(ix = 1; ix < rawlen; ix++)
raw[ix] = (rand() * rand()) & UCHAR_MAX;
raw[1] |= 0x80; /* set high-order bit of test value */
raw[rawlen - 1] |= 1; /* set low-order bit of test value */
/* Make an mp_int out of the initializer */
mp_read_raw(&testval, (char *)raw, rawlen);
/* Initialize candidate counter */
nTries = 0;
start = clock(); /* time generation for this prime */
do {
res = mpp_make_prime(&testval, bits, g_strong, &nTries);
if (res != MP_NO)
break;
/* This code works whether digits are 16 or 32 bits */
res = mp_add_d(&testval, 32 * 1024, &testval);
res = mp_add_d(&testval, 32 * 1024, &testval);
FPUTC(',', stderr);
} while (1);
end = clock();
if (res != MP_YES) {
break;
}
FPUTC('\n', stderr);
puts("The following value is probably prime:");
outlen = mp_radix_size(&testval, 10);
out = calloc(outlen, sizeof(unsigned char));
mp_toradix(&testval, (char *)out, 10);
printf("10: %s\n", out);
mp_toradix(&testval, (char *)out, 16);
printf("16: %s\n\n", out);
free(out);
printf("Number of candidates tried: %lu\n", nTries);
printf("This computation took %ld clock ticks (%.2f seconds)\n",
(end - start), ((double)(end - start) / CLOCKS_PER_SEC));
FPUTC('\n', stderr);
} /* end of loop to generate all requested primes */
if(res != MP_OKAY)
fprintf(stderr, "%s: error: %s\n", argv[0], mp_strerror(res));
free(raw);
mp_clear(&testval);
return 0;
}
