int ec_GFp_simple_set_compressed_coordinates(const EC_GROUP *group,
EC_POINT *point, const BIGNUM *x_,
int y_bit, BN_CTX *ctx) {
BN_CTX *new_ctx = NULL;
BIGNUM *tmp1, *tmp2, *x, *y;
int ret = 0;
ERR_clear_error();
if (ctx == NULL) {
ctx = new_ctx = BN_CTX_new();
if (ctx == NULL) {
return 0;
}
}
y_bit = (y_bit != 0);
BN_CTX_start(ctx);
tmp1 = BN_CTX_get(ctx);
tmp2 = BN_CTX_get(ctx);
x = BN_CTX_get(ctx);
y = BN_CTX_get(ctx);
if (y == NULL) {
goto err;
}
/* Recover y. We have a Weierstrass equation
* y^2 = x^3 + a*x + b,
* so y is one of the square roots of x^3 + a*x + b. */
/* tmp1 := x^3 */
if (!BN_nnmod(x, x_, &group->field, ctx)) {
goto err;
}
if (group->meth->field_decode == 0) {
/* field_{sqr,mul} work on standard representation */
if (!group->meth->field_sqr(group, tmp2, x_, ctx) ||
!group->meth->field_mul(group, tmp1, tmp2, x_, ctx)) {
goto err;
}
} else {
if (!BN_mod_sqr(tmp2, x_, &group->field, ctx) ||
!BN_mod_mul(tmp1, tmp2, x_, &group->field, ctx)) {
goto err;
}
}
/* tmp1 := tmp1 + a*x */
if (group->a_is_minus3) {
if (!BN_mod_lshift1_quick(tmp2, x, &group->field) ||
!BN_mod_add_quick(tmp2, tmp2, x, &group->field) ||
!BN_mod_sub_quick(tmp1, tmp1, tmp2, &group->field)) {
goto err;
}
} else {
if (group->meth->field_decode) {
if (!group->meth->field_decode(group, tmp2, &group->a, ctx) ||
!BN_mod_mul(tmp2, tmp2, x, &group->field, ctx)) {
goto err;
}
} else {
/* field_mul works on standard representation */
if (!group->meth->field_mul(group, tmp2, &group->a, x, ctx)) {
goto err;
}
}
if (!BN_mod_add_quick(tmp1, tmp1, tmp2, &group->field)) {
goto err;
}
}
/* tmp1 := tmp1 + b */
if (group->meth->field_decode) {
if (!group->meth->field_decode(group, tmp2, &group->b, ctx) ||
!BN_mod_add_quick(tmp1, tmp1, tmp2, &group->field)) {
goto err;
}
} else {
if (!BN_mod_add_quick(tmp1, tmp1, &group->b, &group->field)) {
goto err;
}
}
if (!BN_mod_sqrt(y, tmp1, &group->field, ctx)) {
unsigned long err = ERR_peek_last_error();
if (ERR_GET_LIB(err) == ERR_LIB_BN &&
ERR_GET_REASON(err) == BN_R_NOT_A_SQUARE) {
ERR_clear_error();
OPENSSL_PUT_ERROR(EC, ec_GFp_simple_set_compressed_coordinates, EC_R_INVALID_COMPRESSED_POINT);
} else {
OPENSSL_PUT_ERROR(EC, ec_GFp_simple_set_compressed_coordinates, ERR_R_BN_LIB);
}
goto err;
}
if (y_bit != BN_is_odd(y)) {
if (BN_is_zero(y)) {
int kron;
kron = BN_kronecker(x, &group->field, ctx);
if (kron == -2) {
goto err;
}
if (kron == 1) {
OPENSSL_PUT_ERROR(EC, ec_GFp_simple_set_compressed_coordinates,
EC_R_INVALID_COMPRESSION_BIT);
} else {
/* BN_mod_sqrt() should have cought this error (not a square) */
OPENSSL_PUT_ERROR(EC, ec_GFp_simple_set_compressed_coordinates,
EC_R_INVALID_COMPRESSED_POINT);
}
goto err;
}
if (!BN_usub(y, &group->field, y)) {
goto err;
}
}
if (y_bit != BN_is_odd(y)) {
OPENSSL_PUT_ERROR(EC, ec_GFp_simple_set_compressed_coordinates,
ERR_R_INTERNAL_ERROR);
goto err;
}
if (!EC_POINT_set_affine_coordinates_GFp(group, point, x, y, ctx))
goto err;
ret = 1;
err:
BN_CTX_end(ctx);
if (new_ctx != NULL)
BN_CTX_free(new_ctx);
return ret;
}
int test_kron(BIO *bp, BN_CTX *ctx)
{
BIGNUM *a,*b,*r,*t;
int i;
int legendre, kronecker;
int ret = 0;
a = BN_new();
b = BN_new();
r = BN_new();
t = BN_new();
if (a == NULL || b == NULL || r == NULL || t == NULL) goto err;
/* We test BN_kronecker(a, b, ctx) just for b odd (Jacobi symbol).
* In this case we know that if b is prime, then BN_kronecker(a, b, ctx)
* is congruent to $a^{(b-1)/2}$, modulo $b$ (Legendre symbol).
* So we generate a random prime b and compare these values
* for a number of random a's. (That is, we run the Solovay-Strassen
* primality test to confirm that b is prime, except that we
* don't want to test whether b is prime but whether BN_kronecker
* works.) */
if (!BN_generate_prime(b, 512, 0, NULL, NULL, genprime_cb, NULL)) goto err;
b->neg = rand_neg();
putc('\n', stderr);
for (i = 0; i < num0; i++)
{
if (!BN_bntest_rand(a, 512, 0, 0)) goto err;
a->neg = rand_neg();
/* t := (|b|-1)/2 (note that b is odd) */
if (!BN_copy(t, b)) goto err;
t->neg = 0;
if (!BN_sub_word(t, 1)) goto err;
if (!BN_rshift1(t, t)) goto err;
/* r := a^t mod b */
b->neg=0;
if (!BN_mod_exp_recp(r, a, t, b, ctx)) goto err;
b->neg=1;
if (BN_is_word(r, 1))
legendre = 1;
else if (BN_is_zero(r))
legendre = 0;
else
{
if (!BN_add_word(r, 1)) goto err;
if (0 != BN_ucmp(r, b))
{
fprintf(stderr, "Legendre symbol computation failed\n");
goto err;
}
legendre = -1;
}
kronecker = BN_kronecker(a, b, ctx);
if (kronecker < -1) goto err;
/* we actually need BN_kronecker(a, |b|) */
if (a->neg && b->neg)
kronecker = -kronecker;
if (legendre != kronecker)
{
fprintf(stderr, "legendre != kronecker; a = ");
BN_print_fp(stderr, a);
fprintf(stderr, ", b = ");
BN_print_fp(stderr, b);
fprintf(stderr, "\n");
goto err;
}
putc('.', stderr);
fflush(stderr);
}
putc('\n', stderr);
fflush(stderr);
ret = 1;
err:
if (a != NULL) BN_free(a);
if (b != NULL) BN_free(b);
if (r != NULL) BN_free(r);
if (t != NULL) BN_free(t);
return ret;
}
BIGNUM *BN_mod_sqrt(BIGNUM *in, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
/* Returns 'ret' such that
* ret^2 == a (mod p),
* using the Tonelli/Shanks algorithm (cf. Henri Cohen, "A Course
* in Algebraic Computational Number Theory", algorithm 1.5.1).
* 'p' must be prime!
*/
{
BIGNUM *ret = in;
int err = 1;
int r;
BIGNUM *A, *b, *q, *t, *x, *y;
int e, i, j;
if (!BN_is_odd(p) || BN_abs_is_word(p, 1))
{
if (BN_abs_is_word(p, 2))
{
if (ret == NULL)
ret = BN_new();
if (ret == NULL)
goto end;
if (!BN_set_word(ret, BN_is_bit_set(a, 0)))
{
if (ret != in)
BN_free(ret);
return NULL;
}
bn_check_top(ret);
return ret;
}
BNerr(BN_F_BN_MOD_SQRT, BN_R_P_IS_NOT_PRIME);
return(NULL);
}
if (BN_is_zero(a) || BN_is_one(a))
{
if (ret == NULL)
ret = BN_new();
if (ret == NULL)
goto end;
if (!BN_set_word(ret, BN_is_one(a)))
{
if (ret != in)
BN_free(ret);
return NULL;
}
bn_check_top(ret);
return ret;
}
BN_CTX_start(ctx);
A = BN_CTX_get(ctx);
b = BN_CTX_get(ctx);
q = BN_CTX_get(ctx);
t = BN_CTX_get(ctx);
x = BN_CTX_get(ctx);
y = BN_CTX_get(ctx);
if (y == NULL) goto end;
if (ret == NULL)
ret = BN_new();
if (ret == NULL) goto end;
/* A = a mod p */
if (!BN_nnmod(A, a, p, ctx)) goto end;
/* now write |p| - 1 as 2^e*q where q is odd */
e = 1;
while (!BN_is_bit_set(p, e))
e++;
/* we'll set q later (if needed) */
if (e == 1)
{
/* The easy case: (|p|-1)/2 is odd, so 2 has an inverse
* modulo (|p|-1)/2, and square roots can be computed
* directly by modular exponentiation.
* We have
* 2 * (|p|+1)/4 == 1 (mod (|p|-1)/2),
* so we can use exponent (|p|+1)/4, i.e. (|p|-3)/4 + 1.
*/
if (!BN_rshift(q, p, 2)) goto end;
q->neg = 0;
if (!BN_add_word(q, 1)) goto end;
if (!BN_mod_exp(ret, A, q, p, ctx)) goto end;
err = 0;
goto vrfy;
}
if (e == 2)
{
/* |p| == 5 (mod 8)
*
* In this case 2 is always a non-square since
* Legendre(2,p) = (-1)^((p^2-1)/8) for any odd prime.
* So if a really is a square, then 2*a is a non-square.
* Thus for
* b := (2*a)^((|p|-5)/8),
* i := (2*a)*b^2
* we have
* i^2 = (2*a)^((1 + (|p|-5)/4)*2)
* = (2*a)^((p-1)/2)
* = -1;
* so if we set
* x := a*b*(i-1),
* then
* x^2 = a^2 * b^2 * (i^2 - 2*i + 1)
* = a^2 * b^2 * (-2*i)
* = a*(-i)*(2*a*b^2)
* = a*(-i)*i
* = a.
*
* (This is due to A.O.L. Atkin,
* <URL: http://listserv.nodak.edu/scripts/wa.exe?A2=ind9211&L=nmbrthry&O=T&P=562>,
* November 1992.)
*/
/* t := 2*a */
if (!BN_mod_lshift1_quick(t, A, p)) goto end;
/* b := (2*a)^((|p|-5)/8) */
if (!BN_rshift(q, p, 3)) goto end;
q->neg = 0;
if (!BN_mod_exp(b, t, q, p, ctx)) goto end;
/* y := b^2 */
if (!BN_mod_sqr(y, b, p, ctx)) goto end;
/* t := (2*a)*b^2 - 1*/
if (!BN_mod_mul(t, t, y, p, ctx)) goto end;
if (!BN_sub_word(t, 1)) goto end;
/* x = a*b*t */
if (!BN_mod_mul(x, A, b, p, ctx)) goto end;
if (!BN_mod_mul(x, x, t, p, ctx)) goto end;
if (!BN_copy(ret, x)) goto end;
err = 0;
goto vrfy;
}
/* e > 2, so we really have to use the Tonelli/Shanks algorithm.
* First, find some y that is not a square. */
if (!BN_copy(q, p)) goto end; /* use 'q' as temp */
q->neg = 0;
i = 2;
do
{
/* For efficiency, try small numbers first;
* if this fails, try random numbers.
*/
if (i < 22)
{
if (!BN_set_word(y, i)) goto end;
}
else
{
if (!BN_pseudo_rand(y, BN_num_bits(p), 0, 0)) goto end;
if (BN_ucmp(y, p) >= 0)
{
if (!(p->neg ? BN_add : BN_sub)(y, y, p)) goto end;
}
/* now 0 <= y < |p| */
if (BN_is_zero(y))
if (!BN_set_word(y, i)) goto end;
}
r = BN_kronecker(y, q, ctx); /* here 'q' is |p| */
if (r < -1) goto end;
if (r == 0)
{
/* m divides p */
BNerr(BN_F_BN_MOD_SQRT, BN_R_P_IS_NOT_PRIME);
goto end;
}
}
while (r == 1 && ++i < 82);
if (r != -1)
{
/* Many rounds and still no non-square -- this is more likely
* a bug than just bad luck.
* Even if p is not prime, we should have found some y
* such that r == -1.
*/
BNerr(BN_F_BN_MOD_SQRT, BN_R_TOO_MANY_ITERATIONS);
goto end;
}
/* Here's our actual 'q': */
if (!BN_rshift(q, q, e)) goto end;
/* Now that we have some non-square, we can find an element
* of order 2^e by computing its q'th power. */
if (!BN_mod_exp(y, y, q, p, ctx)) goto end;
if (BN_is_one(y))
{
BNerr(BN_F_BN_MOD_SQRT, BN_R_P_IS_NOT_PRIME);
goto end;
}
/* Now we know that (if p is indeed prime) there is an integer
* k, 0 <= k < 2^e, such that
*
* a^q * y^k == 1 (mod p).
*
* As a^q is a square and y is not, k must be even.
* q+1 is even, too, so there is an element
*
* X := a^((q+1)/2) * y^(k/2),
*
* and it satisfies
*
* X^2 = a^q * a * y^k
* = a,
*
* so it is the square root that we are looking for.
*/
/* t := (q-1)/2 (note that q is odd) */
if (!BN_rshift1(t, q)) goto end;
/* x := a^((q-1)/2) */
if (BN_is_zero(t)) /* special case: p = 2^e + 1 */
{
if (!BN_nnmod(t, A, p, ctx)) goto end;
if (BN_is_zero(t))
{
/* special case: a == 0 (mod p) */
BN_zero(ret);
err = 0;
goto end;
}
else
if (!BN_one(x)) goto end;
}
else
{
if (!BN_mod_exp(x, A, t, p, ctx)) goto end;
if (BN_is_zero(x))
{
/* special case: a == 0 (mod p) */
BN_zero(ret);
err = 0;
goto end;
}
}
/* b := a*x^2 (= a^q) */
if (!BN_mod_sqr(b, x, p, ctx)) goto end;
if (!BN_mod_mul(b, b, A, p, ctx)) goto end;
/* x := a*x (= a^((q+1)/2)) */
if (!BN_mod_mul(x, x, A, p, ctx)) goto end;
while (1)
{
/* Now b is a^q * y^k for some even k (0 <= k < 2^E
* where E refers to the original value of e, which we
* don't keep in a variable), and x is a^((q+1)/2) * y^(k/2).
*
* We have a*b = x^2,
* y^2^(e-1) = -1,
* b^2^(e-1) = 1.
*/
if (BN_is_one(b))
{
if (!BN_copy(ret, x)) goto end;
err = 0;
goto vrfy;
}
/* find smallest i such that b^(2^i) = 1 */
i = 1;
if (!BN_mod_sqr(t, b, p, ctx)) goto end;
while (!BN_is_one(t))
{
i++;
if (i == e)
{
BNerr(BN_F_BN_MOD_SQRT, BN_R_NOT_A_SQUARE);
goto end;
}
if (!BN_mod_mul(t, t, t, p, ctx)) goto end;
}
/* t := y^2^(e - i - 1) */
if (!BN_copy(t, y)) goto end;
for (j = e - i - 1; j > 0; j--)
{
if (!BN_mod_sqr(t, t, p, ctx)) goto end;
}
if (!BN_mod_mul(y, t, t, p, ctx)) goto end;
if (!BN_mod_mul(x, x, t, p, ctx)) goto end;
if (!BN_mod_mul(b, b, y, p, ctx)) goto end;
e = i;
}
vrfy:
if (!err)
{
/* verify the result -- the input might have been not a square
* (test added in 0.9.8) */
if (!BN_mod_sqr(x, ret, p, ctx))
err = 1;
if (!err && 0 != BN_cmp(x, A))
{
BNerr(BN_F_BN_MOD_SQRT, BN_R_NOT_A_SQUARE);
err = 1;
}
}
end:
if (err)
{
if (ret != NULL && ret != in)
{
BN_clear_free(ret);
}
ret = NULL;
}
BN_CTX_end(ctx);
bn_check_top(ret);
return ret;
}
void do_mul_exp(BIGNUM *r, BIGNUM *a, BIGNUM *b, BIGNUM *c, BN_CTX *ctx)
{
int i,k;
double tm;
long num;
num=BASENUM;
for (i=NUM_START; i<NUM_SIZES; i++)
{
#ifdef C_PRIME
# ifdef TEST_SQRT
if (!BN_set_word(a, 64)) goto err;
if (!BN_set_word(b, P_MOD_64)) goto err;
# define ADD a
# define REM b
# else
# define ADD NULL
# define REM NULL
# endif
if (!BN_generate_prime(c,sizes[i],0,ADD,REM,genprime_cb,NULL)) goto err;
putc('\n', stderr);
fflush(stderr);
#endif
for (k=0; k<num; k++)
{
if (k%50 == 0) /* Average over num/50 different choices of random numbers. */
{
if (!BN_pseudo_rand(a,sizes[i],1,0)) goto err;
if (!BN_pseudo_rand(b,sizes[i],1,0)) goto err;
#ifndef C_PRIME
if (!BN_pseudo_rand(c,sizes[i],1,1)) goto err;
#endif
#ifdef TEST_SQRT
if (!BN_mod_sqr(a,a,c,ctx)) goto err;
if (!BN_mod_sqr(b,b,c,ctx)) goto err;
#else
if (!BN_nnmod(a,a,c,ctx)) goto err;
if (!BN_nnmod(b,b,c,ctx)) goto err;
#endif
if (k == 0)
Time_F(START);
}
#if defined(TEST_EXP)
if (!BN_mod_exp(r,a,b,c,ctx)) goto err;
#elif defined(TEST_MUL)
{
int i = 0;
for (i = 0; i < 50; i++)
if (!BN_mod_mul(r,a,b,c,ctx)) goto err;
}
#elif defined(TEST_SQR)
{
int i = 0;
for (i = 0; i < 50; i++)
{
if (!BN_mod_sqr(r,a,c,ctx)) goto err;
if (!BN_mod_sqr(r,b,c,ctx)) goto err;
}
}
#elif defined(TEST_GCD)
if (!BN_gcd(r,a,b,ctx)) goto err;
if (!BN_gcd(r,b,c,ctx)) goto err;
if (!BN_gcd(r,c,a,ctx)) goto err;
#elif defined(TEST_KRON)
if (-2 == BN_kronecker(a,b,ctx)) goto err;
if (-2 == BN_kronecker(b,c,ctx)) goto err;
if (-2 == BN_kronecker(c,a,ctx)) goto err;
#elif defined(TEST_INV)
if (!BN_mod_inverse(r,a,c,ctx)) goto err;
if (!BN_mod_inverse(r,b,c,ctx)) goto err;
#else /* TEST_SQRT */
if (!BN_mod_sqrt(r,a,c,ctx)) goto err;
if (!BN_mod_sqrt(r,b,c,ctx)) goto err;
#endif
}
tm=Time_F(STOP);
printf(
#if defined(TEST_EXP)
"modexp %4d ^ %4d %% %4d"
#elif defined(TEST_MUL)
"50*modmul %4d %4d %4d"
#elif defined(TEST_SQR)
"100*modsqr %4d %4d %4d"
#elif defined(TEST_GCD)
"3*gcd %4d %4d %4d"
#elif defined(TEST_KRON)
"3*kronecker %4d %4d %4d"
#elif defined(TEST_INV)
"2*inv %4d %4d mod %4d"
#else /* TEST_SQRT */
"2*sqrt [prime == %d (mod 64)] %4d %4d mod %4d"
#endif
" -> %8.3fms %5.1f (%ld)\n",
#ifdef TEST_SQRT
P_MOD_64,
#endif
sizes[i],sizes[i],sizes[i],tm*1000.0/num,tm*mul_c[i]/num, num);
num/=7;
if (num <= 0) num=1;
}
return;
err:
ERR_print_errors_fp(stderr);
}
