/*
Helper function for ref_zn_array_unpack().
Inverse operation of ref_zn_array_pack_helper(); each output coefficient
occupies ceil(b / ULONG_BITS) ulongs.
Running time is soft-linear in output length.
*/
void
ref_zn_array_unpack_helper (ulong* res, const mpz_t op, size_t n, unsigned b,
unsigned k)
{
ZNP_ASSERT (n >= 1);
ZNP_ASSERT (mpz_sizeinbase (op, 2) <= n * b + k);
unsigned w = CEIL_DIV (b, ULONG_BITS);
mpz_t y;
mpz_init (y);
if (n == 1)
{
// base case
unsigned i;
mpz_tdiv_q_2exp (y, op, k);
for (i = 0; i < w; i++)
{
res[i] = mpz_get_ui (y);
mpz_tdiv_q_2exp (y, y, ULONG_BITS);
}
}
else
{
// recursively split into top and bottom halves
mpz_tdiv_q_2exp (y, op, (n / 2) * b + k);
ref_zn_array_unpack_helper (res + w * (n / 2), y, n - n / 2, b, 0);
mpz_tdiv_r_2exp (y, op, (n / 2) * b + k);
ref_zn_array_unpack_helper (res, y, n / 2, b, k);
}
mpz_clear (y);
}
/* Select the 2, 4, or 6 numbers we will try to factor. */
static void choose_m(mpz_t* mlist, long D, mpz_t u, mpz_t v, mpz_t N,
mpz_t t, mpz_t Nminus1)
{
int i;
mpz_add_ui(Nminus1, N, 1);
mpz_add(mlist[0], Nminus1, u);
mpz_sub(mlist[1], Nminus1, u);
for (i = 2; i < 6; i++)
mpz_set_ui(mlist[i], 0);
if (D == -3) {
/* If reading Cohen, be sure to see the errata for page 474. */
mpz_mul_si(t, v, 3);
mpz_add(t, t, u);
mpz_tdiv_q_2exp(t, t, 1);
mpz_add(mlist[2], Nminus1, t);
mpz_sub(mlist[3], Nminus1, t);
mpz_mul_si(t, v, -3);
mpz_add(t, t, u);
mpz_tdiv_q_2exp(t, t, 1);
mpz_add(mlist[4], Nminus1, t);
mpz_sub(mlist[5], Nminus1, t);
} else if (D == -4) {
mpz_mul_ui(t, v, 2);
mpz_add(mlist[2], Nminus1, t);
mpz_sub(mlist[3], Nminus1, t);
}
/* m must not be prime */
for (i = 0; i < 6; i++)
if (mpz_sgn(mlist[i]) && _GMP_is_prob_prime(mlist[i]))
mpz_set_ui(mlist[i], 0);
}
/* Key comes in form .... M_2 M_1 K_0,
unmask is K_i = K_i-1 * M_i mod Q */
int
gostdsa_unmask_key (const struct ecc_curve *ecc,
mpz_t key)
{
unsigned bits = ecc_bit_size (ecc);
unsigned keybits = mpz_sizeinbase (key, 2);
mpz_t unmasked, temp, temp2, q;
if (keybits <= bits)
return 0;
mpz_init (unmasked);
mpz_init (temp);
mpz_init (temp2);
mpz_roinit_n (q, ecc->q.m, ecc->q.size);
mpz_tdiv_r_2exp (unmasked, key, bits);
mpz_tdiv_q_2exp (key, key, bits);
keybits -= bits;
while (keybits > bits)
{
mpz_tdiv_r_2exp (temp2, key, bits);
mpz_tdiv_q_2exp (key, key, bits);
keybits -= bits;
mpz_mul (temp, unmasked, temp2);
mpz_mod (unmasked, temp, q);
}
mpz_mul (temp, unmasked, key);
mpz_mod (key, temp, q);
mpz_clear (temp2);
mpz_clear (temp);
mpz_clear (unmasked);
return 0;
}
static inline void
fib_matrix_pow (mpz_t a, mpz_t b, mpz_t c, mpz_t d, mpz_t term)
{
mpz_t half_term;
if (mpz_cmp_ui (term, 1) == 0) return;
mpz_init (half_term);
if (mpz_even_p (term)) {
mpz_tdiv_q_2exp (half_term, term, 1);
fib_matrix_pow (a, b, c, d, half_term);
fib_matrix_square (a, b, c, d);
} else {
mpz_t e, f, g, h;
mpz_init_set (e, a);
mpz_init_set (f, b);
mpz_init_set (g, c);
mpz_init_set (h, d);
mpz_sub_ui (half_term, term, 1);
mpz_tdiv_q_2exp (half_term, half_term, 1);
fib_matrix_pow (a, b, c, d, half_term);
fib_matrix_square (a, b, c, d);
fib_matrix_mul (a, b, c, d, e, f, g, h);
mpz_clear (e);
mpz_clear (f);
mpz_clear (g);
mpz_clear (h);
}
mpz_clear (half_term);
}
int checkBl(mpz_t n, uint32 *qli, fb_list *fb, mpz_t *Bl, int s)
{
//check that Bl^2 == N mod ql and Bl == 0 mod qj for 1<=j<=s, j != l
int i,j,p,q;
mpz_t t1,t2;
mpz_init(t1);
mpz_init(t2);
for (i=0;i<s;i++)
{
p = fb->list->prime[qli[i]];
mpz_tdiv_q_2exp(t2, Bl[i], 1); //zShiftRight(&t2,&Bl[i],1);
mpz_mul(t1, t2, t2); //zSqr(&t2,&t1);
if (mpz_tdiv_ui(t1,p) % mpz_tdiv_ui(n,p) != 0)
printf("%s^2 mod %u != N mod %u\n",mpz_conv2str(&gstr1.s, 10, Bl[i]),p,p);
for (j=0;j<s;j++)
{
if (j==i)
continue;
q = fb->list->prime[qli[j]];
mpz_tdiv_q_2exp(t2, Bl[i], 1); //zShiftRight(&t2,&Bl[i],1);
if (mpz_tdiv_ui(t2,q) != 0)
printf("%s mod %u != 0\n",mpz_conv2str(&gstr1.s, 10, Bl[i]),q);
}
}
mpz_clear(t1);
mpz_clear(t2);
return 0;
}
static void zp_halve(element_ptr n, element_ptr a) {
mpz_ptr z = a->data;
if (mpz_odd_p(z)) {
mpz_add(n->data, z, a->field->order);
mpz_tdiv_q_2exp(n->data, n->data, 1);
} else {
mpz_tdiv_q_2exp(n->data, a->data, 1);
}
}
void gmp_halve(mpz_ptr value, mpz_ptr order) {
if (mpz_odd_p(value)) {
mpz_add(value, value, order);
mpz_tdiv_q_2exp(value, value, 1);
} else {
mpz_tdiv_q_2exp(value, value, 1);
}
}
static void
mpfr_const_euler_S2_aux (mpz_t P, mpz_t Q, mpz_t T, unsigned long n,
unsigned long a, unsigned long b, int need_P)
{
if (a + 1 == b)
{
mpz_set_ui (P, n);
if (a > 1)
mpz_mul_si (P, P, 1 - (long) a);
mpz_set (T, P);
mpz_set_ui (Q, a);
mpz_mul_ui (Q, Q, a);
}
else
{
unsigned long c = (a + b) / 2;
mpz_t P2, Q2, T2;
mpfr_const_euler_S2_aux (P, Q, T, n, a, c, 1);
mpz_init (P2);
mpz_init (Q2);
mpz_init (T2);
mpfr_const_euler_S2_aux (P2, Q2, T2, n, c, b, 1);
mpz_mul (T, T, Q2);
mpz_mul (T2, T2, P);
mpz_add (T, T, T2);
if (need_P)
mpz_mul (P, P, P2);
mpz_mul (Q, Q, Q2);
mpz_clear (P2);
mpz_clear (Q2);
mpz_clear (T2);
/* divide by 2 if possible */
{
unsigned long v2;
v2 = mpz_scan1 (P, 0);
c = mpz_scan1 (Q, 0);
if (c < v2)
v2 = c;
c = mpz_scan1 (T, 0);
if (c < v2)
v2 = c;
if (v2)
{
mpz_tdiv_q_2exp (P, P, v2);
mpz_tdiv_q_2exp (Q, Q, v2);
mpz_tdiv_q_2exp (T, T, v2);
}
}
}
}
// Check Fermat probable primality test (2-PRP): 2 ** (n-1) = 1 (mod n)
// true: n is probable prime
// false: n is composite; set fractional length in the nLength output
static bool FermatProbablePrimalityTestFast(const mpz_class& n, unsigned int& nLength, CPrimalityTestParams& testParams, bool fFastFail = false)
{
mpz_class& mpzNMinusOne = testParams.mpzNMinusOne;
mpz_class& mpzE = testParams.mpzE;
mpz_class& mpzBase = testParams.mpzBase;
mpz_class& mpzR = testParams.mpzR;
mpz_class& mpzR2 = testParams.mpzR2;
mpz_class& mpzFrac = testParams.mpzFrac;
mpzNMinusOne = n - 1;
unsigned int nTrailingZeros = mpz_scan1(mpzNMinusOne.get_mpz_t(), 0);
if ((nTrailingZeros > 9))
nTrailingZeros = 9;
// Euler's criterion: 2 ** ((n-1)/2) needs to be either -1 or 1 (mod n)
mpz_tdiv_q_2exp(mpzE.get_mpz_t(), mpzNMinusOne.get_mpz_t(), nTrailingZeros);
unsigned int nShiftCount = (1U << (nTrailingZeros - 1)) - 1;
mpzBase = mpzTwo << nShiftCount;
mpz_powm(mpzR.get_mpz_t(), mpzBase.get_mpz_t(), mpzE.get_mpz_t(), n.get_mpz_t());
if ((mpzR == 1 || mpzR == mpzNMinusOne))
return true;
if ((fFastFail))
return false;
// Failed test, calculate fractional length
mpzR2 = mpzR * mpzR;
mpzR = mpzR2 % n; // derive Fermat test remainder
mpzFrac = n - mpzR;
mpzFrac <<= nFractionalBits;
mpzFrac /= n;
unsigned int nFractionalLength = mpzFrac.get_ui();
if ((nFractionalLength >= (1 << nFractionalBits)))
return false;
nLength = (nLength & TARGET_LENGTH_MASK) | nFractionalLength;
return false;
}
static inline uint64_t
s_bignum_2_uint64_t(MP_INT *v) {
uint64_t ret;
uint32_t lo, hi;
MP_INT posv;
MP_INT z_lo;
MP_INT z_hi;
bool is_neg = (mpz_sgn(v) < 0) ? true : false;
mpz_init(&z_lo);
mpz_init(&z_hi);
if (is_neg == true) {
mpz_init(&posv);
mpz_neg(&posv, v);
v = &posv;
}
mpz_tdiv_q_2exp(&z_hi, v, 32);
mpz_tdiv_r_2exp(&z_lo, v, 32);
hi = mpz_get_ui(&z_hi);
lo = mpz_get_ui(&z_lo);
mpz_clear(&z_hi);
mpz_clear(&z_lo);
ret = ((uint64_t)hi << 32) | (uint64_t)lo;
if (is_neg == true) {
ret--;
ret = ~ret;
mpz_clear(&posv);
}
return ret;
}
static obj bignum_compact(mpz_t a)
{
INT_64 b;
UINT_32 c;
if(abs(a[0]._mp_size) > 64/mp_bits_per_limb)
return mpz_to_bignum(a);
if(abs(a[0]._mp_size) < 64/mp_bits_per_limb)
c = 0;
else {
mpz_t d;
mpz_init(d);
mpz_tdiv_q_2exp(d, a, CHAR_BIT*sizeof(unsigned long int));
c=mpz_get_ui(d);
if(mpz_sgn(a) > 0 && (c&(1<<(CHAR_BIT*sizeof(unsigned long int)-1))))
return mpz_to_bignum(a);
}
#ifndef HAVE_INT_64
b.digits[0] = c >> 16;
b.digits[1] = c & 0xffff;
c = mpz_get_ui(a);
b.digits[2] = c >> 16;
b.digits[3] = c & 0xffff;
if(mpz_sgn(a) < 0)
b = int_64_neg(b);
#else
b = c;
b <<= 32;
b |= mpz_get_ui(a);
if(mpz_sgn(a) < 0)
b = -b;
#endif
return int_64_compact(b);
}
/* Implements Legendre symbol only, requiring that p is an odd prime */
static int
mpz_ui_kronecker (mp_limb_t ul, const mpz_t p)
{
mpz_t t, u;
int r;
mpz_init_set_ui (u, ul);
mpz_init_set (t, p);
mpz_sub_ui (t, t, 1);
mpz_tdiv_q_2exp (t, t, 1);
mpz_powm (t, u, t, p);
r = mpz_cmp_ui (t, 1);
if (r < 0)
r = 0;
else if (r == 0)
r = 1;
else
{
mpz_sub (t, p, t);
ASSERT (mpz_cmp_ui (t, 1) == 0);
r = -1;
}
mpz_clear (t);
mpz_clear (u);
return r;
}
static PyObject *
GMPy_MPZ_t_div_2exp(PyObject *self, PyObject *args)
{
mp_bitcnt_t nbits;
MPZ_Object *result, *tempx;
if (PyTuple_GET_SIZE(args) != 2) {
TYPE_ERROR("t_div_2exp() requires 'mpz','int' arguments");
return NULL;
}
nbits = mp_bitcnt_t_From_Integer(PyTuple_GET_ITEM(args, 1));
if (nbits == (mp_bitcnt_t)(-1) && PyErr_Occurred()) {
return NULL;
}
tempx = GMPy_MPZ_From_Integer(PyTuple_GET_ITEM(args, 0), NULL);
result = GMPy_MPZ_New(NULL);
if (!tempx || !result) {
Py_XDECREF((PyObject*)result);
Py_XDECREF((PyObject*)tempx);
return NULL;
}
mpz_tdiv_q_2exp(result->z, tempx->z, nbits);
Py_DECREF((PyObject*)tempx);
return (PyObject*)result;
}
ring_elem RingZZ::remainderAndQuotient(const ring_elem f, const ring_elem g,
ring_elem ") const
{
mpz_ptr q = new_elem();
mpz_ptr r = new_elem();
int gsign = mpz_sgn(g.get_mpz());
mpz_t gg, ghalf;
mpz_init(gg);
mpz_init(ghalf);
mpz_abs(gg,g.get_mpz());
mpz_fdiv_qr(q, r, f.get_mpz(), gg);
mpz_tdiv_q_2exp(ghalf, gg, 1);
if (mpz_cmp(r,ghalf) > 0) // r > ghalf
{
mpz_sub(r,r,gg);
mpz_add_ui(q,q,1);
}
if (gsign < 0)
mpz_neg(q,q);
mpz_clear(gg);
mpz_clear(ghalf);
quot = ring_elem(q);
return ring_elem(r);
}
void BigNum::add(BigNum & r, BigNum & x, BigNum & y) // result of x + y will be stored in r, x and y will be changed
{
//r.denominator = x.denominator + y.denominator;
if (x.denominator >= y.denominator)
{
r.denominator = x.denominator;
mpz_mul_2exp(y.numerator, y.numerator, x.denominator - y.denominator);
}
else
{
r.denominator = y.denominator;
mpz_mul_2exp(x.numerator, x.numerator, y.denominator - x.denominator);
}
mpz_add(r.numerator, x.numerator, y.numerator);
r.zero_flag = false; // any result should be > 0
unsigned index = 0;
while(!mpz_tstbit(r.numerator, index)) // mpz_tstbit(r.numerator, index) == 0, test 0 bit by bit
++index;
if (index > 0) // reduce numerator and denominator as much as possible
{
mpz_tdiv_q_2exp(r.numerator, r.numerator, index);
r.denominator = r.denominator - index;
}
return;
}
int
mpz_remove_twos (mpz_t x)
{
mp_bitcnt_t r = mpz_scan1(x, 0);
mpz_tdiv_q_2exp (x, x, r);
return r;
}
static obj bignum_shr( obj a, INT_32 b)
{
mpz_t r, a1;
OBJ_TO_MPZ(a1, a);
mpz_init(r);
mpz_tdiv_q_2exp(r, a1, b);
return bignum_compact(r);
}
//--------------------------------------------------
// square root in extended Fp
//--------------------------------------------------
int bn254_fp2_sqrt(Element z, const Element x)
{
mpz_t _v;
int m, r, i;
field_precomp_sqrt_p ps;
Element *t = field(z)->tmp;
if (!element_is_sqr(x)) {
return FALSE;
}
ps = ((field_precomp_p)(field(x)->precomp))->ps;
element_set(t[0], ps->n_v); // t0 = n^v
r = ps->e; // r = e
mpz_init_set(_v, ps->v);
mpz_sub_ui(_v, _v, 1);
mpz_tdiv_q_2exp(_v, _v, 1);
element_pow(t[1], x, _v); // t1 = x^{(v-1)/2}
element_sqr(t[2], t[1]);
element_mul(t[2], t[2], x); // t2 = x*t1^2
element_mul(t[1], x, t[1]); // t1 = x*t1
mpz_clear(_v);
while (!element_is_one(t[2]))
{
m = 0;
element_set(t[3], t[2]);
do {
element_sqr(t[3], t[3]);
m++;
}
while (!element_is_one(t[3]) && m < r);
r = r - m - 1;
element_set(t[3], t[0]);
for (i = 1; i <= r; i++) {
element_sqr(t[3], t[3]);
} // t3 = t2^{r-m-1}
element_sqr(t[0], t[3]); // t0 = t3^2
r = m;
element_mul(t[1], t[1], t[3]);// t1 = t1*t3
element_mul(t[2], t[2], t[0]);// t2 = t2*t0
}
element_set(z, t[1]);
return TRUE;
}
static void gf3m_sqrt(element_t e, element_t a) {
field_ptr f = e->field;
mpz_t t;
mpz_init(t); // t == (field_order + 1) / 4
mpz_set(t, f->order);
mpz_add_ui(t, t, 1);
mpz_tdiv_q_2exp(t, t, 2);
element_pow_mpz(e, a, t);
mpz_clear(t);
}
/*
First version -- uses Taylor series for exp(x) directly,
broken into two pieces
Note: this version is currently not used in the benchmark below
*/
void fix_exp(mpz_t z, mpz_t x, int prec)
{
int k;
int r = 8;
//prec += 20;
//mpz_set(_exp_x, x);
//mpz_tdiv_q_2exp(_exp_x, _exp_x, r);
mpz_tdiv_q_2exp(_exp_x, x, r);
mpz_set_ui(_exp_s0, 1);
mpz_mul_2exp(_exp_s0, _exp_s0, prec);
mpz_set(_exp_s1, _exp_s0);
mpz_mul(_exp_x2, _exp_x, _exp_x);
mpz_tdiv_q_2exp(_exp_x2,_exp_x2,prec);
mpz_set(_exp_a, _exp_x2);
k = 2;
while(1)
{
mpz_tdiv_q_ui(_exp_a, _exp_a, k);
if (mpz_sgn(_exp_a) == 0)
break;
mpz_add(_exp_s0, _exp_s0, _exp_a);
k += 1;
mpz_tdiv_q_ui(_exp_a, _exp_a, k);
if (mpz_sgn(_exp_a) == 0)
break;
mpz_add(_exp_s1, _exp_s1, _exp_a);
k += 1;
mpz_mul(_exp_a, _exp_a, _exp_x2);
mpz_tdiv_q_2exp(_exp_a,_exp_a,prec);
if (mpz_sgn(_exp_a) == 0)
break;
}
mpz_mul(_exp_s1, _exp_s1, _exp_x);
mpz_tdiv_q_2exp(_exp_s1,_exp_s1,prec);
mpz_add(_exp_s0, _exp_s0, _exp_s1);
for(k=0; k<r; k++)
{
mpz_mul(_exp_s0, _exp_s0, _exp_s0);
mpz_tdiv_q_2exp(_exp_s0,_exp_s0,prec);
}
//mpz_tdiv_q_ui(z, _exp_s0, 20);
mpz_set(z, _exp_s0);
}
/* fix the sign of Re(z) or Im(z) in case it is zero,
and Re(x) is zero.
sign_eps is 0 if Re(x) = +0, 1 if Re(x) = -0
sign_a is the sign bit of Im(x).
Assume y is an integer (does nothing otherwise).
*/
static void
fix_sign (mpc_ptr z, int sign_eps, int sign_a, mpfr_srcptr y)
{
int ymod4 = -1;
mpfr_exp_t ey;
mpz_t my;
unsigned long int t;
mpz_init (my);
ey = mpfr_get_z_exp (my, y);
/* normalize so that my is odd */
t = mpz_scan1 (my, 0);
ey += (mpfr_exp_t) t;
mpz_tdiv_q_2exp (my, my, t);
/* y = my*2^ey */
/* compute y mod 4 (in case y is an integer) */
if (ey >= 2)
ymod4 = 0;
else if (ey == 1)
ymod4 = mpz_tstbit (my, 0) * 2; /* correct if my < 0 */
else if (ey == 0)
{
ymod4 = mpz_tstbit (my, 1) * 2 + mpz_tstbit (my, 0);
if (mpz_cmp_ui (my , 0) < 0)
ymod4 = 4 - ymod4;
}
else /* y is not an integer */
goto end;
if (mpfr_zero_p (mpc_realref(z)))
{
/* we assume y is always integer in that case (FIXME: prove it):
(eps+I*a)^y = +0 + I*a^y for y = 1 mod 4 and sign_eps = 0
(eps+I*a)^y = -0 - I*a^y for y = 3 mod 4 and sign_eps = 0 */
MPC_ASSERT (ymod4 == 1 || ymod4 == 3);
if ((ymod4 == 3 && sign_eps == 0) ||
(ymod4 == 1 && sign_eps == 1))
mpfr_neg (mpc_realref(z), mpc_realref(z), MPFR_RNDZ);
}
else if (mpfr_zero_p (mpc_imagref(z)))
{
/* we assume y is always integer in that case (FIXME: prove it):
(eps+I*a)^y = a^y - 0*I for y = 0 mod 4 and sign_a = sign_eps
(eps+I*a)^y = -a^y +0*I for y = 2 mod 4 and sign_a = sign_eps */
MPC_ASSERT (ymod4 == 0 || ymod4 == 2);
if ((ymod4 == 0 && sign_a == sign_eps) ||
(ymod4 == 2 && sign_a != sign_eps))
mpfr_neg (mpc_imagref(z), mpc_imagref(z), MPFR_RNDZ);
}
end:
mpz_clear (my);
}
int
mpz_millerrabin (mpz_srcptr n, int reps)
{
int r;
mpz_t nm1, nm3, x, y, q;
unsigned long int k;
gmp_randstate_t rstate;
int is_prime;
TMP_DECL;
TMP_MARK;
MPZ_TMP_INIT (nm1, SIZ (n) + 1);
mpz_sub_ui (nm1, n, 1L);
MPZ_TMP_INIT (x, SIZ (n) + 1);
MPZ_TMP_INIT (y, 2 * SIZ (n)); /* mpz_powm_ui needs excessive memory!!! */
/* Perform a Fermat test. */
mpz_set_ui (x, 210L);
mpz_powm (y, x, nm1, n);
if (mpz_cmp_ui (y, 1L) != 0)
{
TMP_FREE;
return 0;
}
MPZ_TMP_INIT (q, SIZ (n));
/* Find q and k, where q is odd and n = 1 + 2**k * q. */
k = mpz_scan1 (nm1, 0L);
mpz_tdiv_q_2exp (q, nm1, k);
/* n-3 */
MPZ_TMP_INIT (nm3, SIZ (n) + 1);
mpz_sub_ui (nm3, n, 3L);
ASSERT (mpz_cmp_ui (nm3, 1L) >= 0);
gmp_randinit_default (rstate);
is_prime = 1;
for (r = 0; r < reps && is_prime; r++)
{
/* 2 to n-2 inclusive, don't want 1, 0 or -1 */
mpz_urandomm (x, rstate, nm3);
mpz_add_ui (x, x, 2L);
is_prime = millerrabin (n, nm1, x, y, q, k);
}
gmp_randclear (rstate);
TMP_FREE;
return is_prime;
}
/* Return non-zero iff c+i*d is an exact square (a+i*b)^2,
with a, b both of the form m*2^e with m, e integers.
If so, returns in a+i*b the corresponding square root, with a >= 0.
The variables a, b must not overlap with c, d.
We have c = a^2 - b^2 and d = 2*a*b.
If one of a, b is exact, then both are (see algorithms.tex).
Case 1: a <> 0 and b <> 0.
Let a = m*2^e and b = n*2^f with m, e, n, f integers, m and n odd
(we will treat apart the case a = 0 or b = 0).
Then 2*a*b = m*n*2^(e+f+1), thus necessarily e+f >= -1.
Assume e < 0, then f >= 0, then a^2 - b^2 = m^2*2^(2e) - n^2*2^(2f) cannot
be an integer, since n^2*2^(2f) is an integer, and m^2*2^(2e) is not.
Similarly when f < 0 (and thus e >= 0).
Thus we have e, f >= 0, and a, b are both integers.
Let A = 2a^2, then eliminating b between c = a^2 - b^2 and d = 2*a*b
gives A^2 - 2c*A - d^2 = 0, which has solutions c +/- sqrt(c^2+d^2).
We thus need c^2+d^2 to be a square, and c + sqrt(c^2+d^2) --- the solution
we are interested in --- to be two times a square. Then b = d/(2a) is
necessarily an integer.
Case 2: a = 0. Then d is necessarily zero, thus it suffices to check
whether c = -b^2, i.e., if -c is a square.
Case 3: b = 0. Then d is necessarily zero, thus it suffices to check
whether c = a^2, i.e., if c is a square.
*/
static int
mpc_perfect_square_p (mpz_t a, mpz_t b, mpz_t c, mpz_t d)
{
if (mpz_cmp_ui (d, 0) == 0) /* case a = 0 or b = 0 */
{
/* necessarily c < 0 here, since we have already considered the case
where x is real non-negative and y is real */
MPC_ASSERT (mpz_cmp_ui (c, 0) < 0);
mpz_neg (b, c);
if (mpz_perfect_square_p (b)) /* case 2 above */
{
mpz_sqrt (b, b);
mpz_set_ui (a, 0);
return 1; /* c + i*d = (0 + i*b)^2 */
}
}
else /* both a and b are non-zero */
{
if (mpz_divisible_2exp_p (d, 1) == 0)
return 0; /* d must be even */
mpz_mul (a, c, c);
mpz_addmul (a, d, d); /* c^2 + d^2 */
if (mpz_perfect_square_p (a))
{
mpz_sqrt (a, a);
mpz_add (a, c, a); /* c + sqrt(c^2+d^2) */
if (mpz_divisible_2exp_p (a, 1))
{
mpz_tdiv_q_2exp (a, a, 1);
if (mpz_perfect_square_p (a))
{
mpz_sqrt (a, a);
mpz_tdiv_q_2exp (b, d, 1); /* d/2 */
mpz_divexact (b, b, a); /* d/(2a) */
return 1;
}
}
}
}
return 0; /* not a square */
}
static void
check_one (mpz_ptr z)
{
int inex;
int sh, neg;
mpfr_t f;
mpz_t got;
mpfr_init2 (f, MAX( mpz_sizeinbase (z, 2), MPFR_PREC_MIN) );
mpz_init (got);
for (sh = -2*GMP_NUMB_BITS ; sh < 2*GMP_NUMB_BITS ; sh++)
{
for (neg = 0; neg <= 1; neg++)
{
mpz_neg (z, z);
mpfr_set_z (f, z, MPFR_RNDN);
if (sh < 0)
{
mpz_tdiv_q_2exp (z, z, -sh);
mpfr_div_2exp (f, f, -sh, MPFR_RNDN);
}
else
{
mpz_mul_2exp (z, z, sh);
mpfr_mul_2exp (f, f, sh, MPFR_RNDN);
}
inex = mpfr_get_z (got, f, MPFR_RNDZ);
if (mpz_cmp (got, z) != 0)
{
printf ("Wrong result for shift=%d\n", sh);
printf (" f "); mpfr_dump (f);
printf (" got "); mpz_dump (got);
printf (" want "); mpz_dump (z);
exit (1);
}
if (! SAME_SIGN (inex, - mpfr_cmp_z (f, z)))
{
printf ("Wrong inexact value for shift=%d\n", sh);
printf (" f "); mpfr_dump (f);
printf (" got %+d\n", inex);
printf (" want %+d\n", -mpfr_cmp_z (f, z));
exit (1);
}
}
}
mpfr_clear (f);
mpz_clear (got);
}
int test__ZmodF_mul_fft_split()
{
int success = 1;
mpz_t x, y, z;
mpz_init(x);
mpz_init(y);
mpz_init(z);
mp_limb_t buf[300];
for (unsigned long n = 1; n < 200 && success; n++)
{
for (unsigned long depth = 0;
((n*FLINT_BITS) % (1 << depth) == 0) && success; depth++)
{
unsigned long bits = (n*FLINT_BITS) >> depth;
unsigned long m = (bits-1)/FLINT_BITS + 1;
ZmodF_poly_t poly;
ZmodF_poly_init(poly, depth, m, 1);
#if DEBUG
printf("n = %d, depth = %d, m = %d\n", n, depth, m);
#endif
for (unsigned long trial = 0; trial < 120; trial++)
{
random_limbs(buf, n);
buf[n] = 0;
mpn_to_mpz(x, buf, n);
_ZmodF_mul_fft_split(poly, buf, n);
for (unsigned long i = 0; i < (1 << depth); i++)
{
mpz_tdiv_r_2exp(y, x, bits);
mpz_tdiv_q_2exp(x, x, bits);
mpn_to_mpz(z, poly->coeffs[i], m+1);
if (mpz_cmp(z, y))
success = 0;
}
}
ZmodF_poly_clear(poly);
}
}
mpz_clear(x);
mpz_clear(y);
mpz_clear(z);
return success;
}
void Element::multiply(Element& A, Element& B) {
// Emulate hardware implementation.
// Set result to 0
mpz_t result;
mpz_init(result);
// Modulus: x^163 + x^7 + x^6 + x^3 + 1 (wordlength 163)
mpz_t mod;
mpz_init(mod);
mpz_set_str(mod, "0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000011001001", 2);
//gmp_printf("Mod = %Zx\n", mod);
// Length of modulus in base 2
int mod_len = 163;
//printf("Len = %d\n", mod_len);
int m = 0;
for (long i = (long) mod_len; i > 0; i--) {
if (mpz_tstbit(A.getMP(), i - 1) == 1) {
mpz_xor(result, result, B.getMP());
}
if (m == 1) {
mpz_xor(result, result, mod);
}
// Set m & T for next round
m = mpz_tstbit(result, mod_len - 1);
// Shift T by 1 bit to the left and clear MSB bit
mpz_clrbit(result, mod_len - 1);
mpz_mul_2exp(result, result, 1);
/*printf("[Mult] i = %d - T = ", mod_len - i + 2);
gmp_printf("0x%Zx\n", result);*/
}
// Shift result back 1 place & place m back in front
mpz_tdiv_q_2exp(result, result, 1);
if (m == 1) {
mpz_setbit(result, 162);
}
/*printf("[Mult] i = 0 - T = ");
gmp_printf("0x%Zx\n", result);*/
// Set result
mpz_set(this->a, result);
}
/* Select the 2, 4, or 6 numbers we will try to factor. */
static void choose_m(mpz_t* mlist, long D, mpz_t u, mpz_t v, mpz_t N,
mpz_t t, mpz_t Nplus1)
{
int i, j;
mpz_add_ui(Nplus1, N, 1);
mpz_sub(mlist[0], Nplus1, u); /* N+1-u */
mpz_add(mlist[1], Nplus1, u); /* N+1+u */
for (i = 2; i < 6; i++)
mpz_set_ui(mlist[i], 0);
if (D == -3) {
/* If reading Cohen, be sure to see the errata for page 474. */
mpz_mul_si(t, v, 3);
mpz_add(t, t, u);
mpz_tdiv_q_2exp(t, t, 1);
mpz_sub(mlist[2], Nplus1, t); /* N+1-(u+3v)/2 */
mpz_add(mlist[3], Nplus1, t); /* N+1+(u+3v)/2 */
mpz_mul_si(t, v, -3);
mpz_add(t, t, u);
mpz_tdiv_q_2exp(t, t, 1);
mpz_sub(mlist[4], Nplus1, t); /* N+1-(u-3v)/2 */
mpz_add(mlist[5], Nplus1, t); /* N+1+(u-3v)/2 */
} else if (D == -4) {
mpz_mul_ui(t, v, 2);
mpz_sub(mlist[2], Nplus1, t); /* N+1-2v */
mpz_add(mlist[3], Nplus1, t); /* N+1+2v */
}
/* m must not be prime */
for (i = 0; i < 6; i++)
if (mpz_sgn(mlist[i]) && _GMP_is_prob_prime(mlist[i]))
mpz_set_ui(mlist[i], 0);
/* Sort the m values so we test the smallest first */
for (i = 0; i < 5; i++)
if (mpz_sgn(mlist[i]))
for (j = i+1; j < 6; j++)
if (mpz_sgn(mlist[j]) && mpz_cmp(mlist[i],mlist[j]) > 0)
mpz_swap( mlist[i], mlist[j] );
}
double mpzln(mpz_t a)
{
int l; double r;
l = mpz_sizeinbase(a,2);
if (l<=1000) r=log(fabs(mpz_get_d(a)));
else {
mpz_t b;
mpz_init(b); mpz_tdiv_q_2exp(b,a,l-900);
r=mpz_get_d(b);
r=(double)l-900.0+log(fabs(r));
mpz_clear(b);
}
return r;
}
int
gmpmee_millerrabin_init(gmpmee_millerrabin_state state, mpz_t n)
{
mpz_init_set(state->n, n);
mpz_init(state->n_minus_1);
mpz_init(state->q);
mpz_init(state->y);
mpz_sub_ui(state->n_minus_1, n, 1L);
/* Define q and k such that n = q*2^k+1. */
state->k = mpz_scan1(state->n_minus_1, 0L);
mpz_tdiv_q_2exp(state->q, state->n_minus_1, state->k);
}
double mpzln(mpz_t a) //calculate ln for arbitrary length integers
{ //I have no idea how this works - probably should try to understand
int l; double r;
l = mpz_sizeinbase(a,2);
if (l<=1000) r=log(fabs(mpz_get_d(a)));
else {
mpz_t b;
mpz_init(b); mpz_tdiv_q_2exp(b,a,l-900);
r=mpz_get_d(b);
r=(double)l-900.0+log(fabs(r));
mpz_clear(b);
}
return r;
}
