void eb_hlv(eb_t r, const eb_t p) {
fb_t l, t;
fb_null(l);
fb_null(t);
TRY {
fb_new(l);
fb_new(t);
/* Solve l^2 + l = u + a. */
switch (eb_curve_opt_a()) {
case RLC_ZERO:
fb_copy(t, p->x);
break;
case RLC_ONE:
fb_add_dig(t, p->x, (dig_t)1);
break;
case RLC_TINY:
fb_add_dig(t, p->x, eb_curve_get_a()[0]);
break;
default:
fb_add(t, p->x, eb_curve_get_a());
break;
}
fb_slv(l, t);
if (p->norm == 1) {
/* Compute t = v + u * lambda. */
fb_mul(t, l, p->x);
fb_add(t, t, p->y);
} else {
/* Compute t = u * (u + lambda_P + lambda). */
fb_add(t, l, p->y);
fb_add(t, t, p->x);
fb_mul(t, t, p->x);
}
/* If Tr(t) = 0 then lambda_P = lambda, u = sqrt(t + u). */
if (fb_trc(t) == 0) {
fb_copy(r->y, l);
fb_add(t, t, p->x);
fb_srt(r->x, t);
} else {
/* Else lambda_P = lambda + 1, u = sqrt(t). */
fb_add_dig(r->y, l, 1);
fb_srt(r->x, t);
}
fb_set_dig(r->z, 1);
r->norm = 2;
}
CATCH_ANY {
THROW(ERR_CAUGHT);
}
FINALLY {
fb_free(l);
fb_free(t);
}
}
void eb_rhs(fb_t rhs, const eb_t p) {
fb_t t0, t1;
fb_null(t0);
fb_null(t1);
TRY {
fb_new(t0);
fb_new(t1);
/* t0 = x1^2. */
fb_sqr(t0, p->x);
/* t1 = x1^3. */
fb_mul(t1, t0, p->x);
/* t1 = x1^3 + a * x1^2 + b. */
switch (eb_curve_opt_a()) {
case OPT_ZERO:
break;
case OPT_ONE:
fb_add(t1, t1, t0);
break;
case OPT_DIGIT:
fb_mul_dig(t0, t0, eb_curve_get_a()[0]);
fb_add(t1, t1, t0);
break;
default:
fb_mul(t0, t0, eb_curve_get_a());
fb_add(t1, t1, t0);
break;
}
switch (eb_curve_opt_b()) {
case OPT_ZERO:
break;
case OPT_ONE:
fb_add_dig(t1, t1, 1);
break;
case OPT_DIGIT:
fb_add_dig(t1, t1, eb_curve_get_b()[0]);
break;
default:
fb_add(t1, t1, eb_curve_get_b());
break;
}
fb_copy(rhs, t1);
}
CATCH_ANY {
THROW(ERR_CAUGHT);
}
FINALLY {
fb_free(t0);
fb_free(t1);
}
}
/**
* Adds a point represented in affine coordinates to a point represented in
* projective coordinates.
*
* @param r - the result.
* @param p - the affine point.
* @param q - the projective point.
*/
static void eb_add_projc_ordin_mix(eb_t r, eb_t p, eb_t q) {
fb_t t0, t1, t2, t3, t4, t5;
fb_null(t0);
fb_null(t1);
fb_null(t2);
fb_null(t3);
fb_null(t4);
fb_null(t5);
TRY {
fb_new(t0);
fb_new(t1);
fb_new(t2);
fb_new(t3);
fb_new(t4);
fb_new(t5);
if (!p->norm) {
/* A = y1 + y2 * z1^2. */
fb_sqr(t0, p->z);
fb_mul(t0, t0, q->y);
fb_add(t0, t0, p->y);
/* B = x1 + x2 * z1. */
fb_mul(t1, p->z, q->x);
fb_add(t1, t1, p->x);
} else {
/* t0 = A = y1 + y2. */
fb_add(t0, p->y, q->y);
/* t1 = B = x1 + x2. */
fb_add(t1, p->x, q->x);
}
if (fb_is_zero(t1)) {
if (fb_is_zero(t0)) {
/* If t0 = 0 and t1 = 0, p = q, should have doubled! */
eb_dbl_projc(r, p);
} else {
/* If t0 = 0, r is infinity. */
eb_set_infty(r);
}
} else {
if (!p->norm) {
/* t2 = C = B * z1. */
fb_mul(t2, p->z, t1);
/* z3 = C^2. */
fb_sqr(r->z, t2);
/* t1 = B^2. */
fb_sqr(t1, t1);
/* t1 = A + B^2. */
fb_add(t1, t0, t1);
} else {
/* If z1 = 0, t2 = C = B. */
fb_copy(t2, t1);
/* z3 = B^2. */
fb_sqr(r->z, t1);
/* t1 = A + z3. */
fb_add(t1, t0, r->z);
}
/* t3 = D = x2 * z3. */
fb_mul(t3, r->z, q->x);
/* t4 = (y2 + x2). */
fb_add(t4, q->x, q->y);
/* z3 = A^2. */
fb_sqr(r->x, t0);
/* t1 = A + B^2 + a2 * C. */
switch (eb_curve_opt_a()) {
case OPT_ZERO:
break;
case OPT_ONE:
fb_add(t1, t1, t2);
break;
case OPT_DIGIT:
/* t5 = a2 * C. */
fb_mul_dig(t5, t2, eb_curve_get_a()[0]);
fb_add(t1, t1, t5);
break;
default:
/* t5 = a2 * C. */
fb_mul(t5, eb_curve_get_a(), t2);
fb_add(t1, t1, t5);
break;
}
/* t1 = C * (A + B^2 + a2 * C). */
fb_mul(t1, t1, t2);
/* x3 = A^2 + C * (A + B^2 + a2 * C). */
fb_add(r->x, r->x, t1);
/* t3 = D + x3. */
fb_add(t3, t3, r->x);
/* t2 = A * B. */
fb_mul(t2, t0, t2);
/* y3 = (D + x3) * (A * B + z3). */
fb_add(r->y, t2, r->z);
fb_mul(r->y, r->y, t3);
/* t0 = z3^2. */
fb_sqr(t0, r->z);
/* t0 = (y2 + x2) * z3^2. */
fb_mul(t0, t0, t4);
/* y3 = (D + x3) * (A * B + z3) + (y2 + x2) * z3^2. */
fb_add(r->y, r->y, t0);
}
r->norm = 0;
}
CATCH_ANY {
THROW(ERR_CAUGHT);
}
FINALLY {
fb_free(t0);
fb_free(t1);
fb_free(t2);
fb_free(t3);
fb_free(t4);
fb_free(t5);
}
}
/**
* Doubles a point represented in affine coordinates on an ordinary binary
* elliptic curve.
*
* @param[out] r - the result.
* @param[in] p - the point to double.
*/
static void eb_dbl_basic_imp(eb_t r, const eb_t p) {
fb_t t0, t1, t2;
fb_null(t0);
fb_null(t1);
fb_null(t2);
TRY {
fb_new(t0);
fb_new(t1);
fb_new(t2);
/* t0 = 1/x1. */
fb_inv(t0, p->x);
/* t0 = y1/x1. */
fb_mul(t0, t0, p->y);
/* t0 = lambda = x1 + y1/x1. */
fb_add(t0, t0, p->x);
/* t1 = lambda^2. */
fb_sqr(t1, t0);
/* t2 = lambda^2 + lambda. */
fb_add(t2, t1, t0);
/* t2 = lambda^2 + lambda + a2. */
switch (eb_curve_opt_a()) {
case OPT_ZERO:
break;
case OPT_ONE:
fb_add_dig(t2, t2, (dig_t)1);
break;
case OPT_DIGIT:
fb_add_dig(t2, t2, eb_curve_get_a()[0]);
break;
default:
fb_add(t2, t2, eb_curve_get_a());
break;
}
/* t1 = x1 + x3. */
fb_add(t1, t2, p->x);
/* t1 = lambda * (x1 + x3). */
fb_mul(t1, t0, t1);
fb_copy(r->x, t2);
/* y3 = lambda * (x1 + x3) + x3 + y1. */
fb_add(t1, t1, r->x);
fb_add(r->y, t1, p->y);
fb_copy(r->z, p->z);
r->norm = 1;
}
CATCH_ANY {
THROW(ERR_CAUGHT);
}
FINALLY {
fb_free(t0);
fb_free(t1);
fb_free(t2);
}
}
/**
* Doubles a point represented in projective coordinates on an ordinary binary
* elliptic curve.
*
* @param[out] r - the result.
* @param[in] p - the point to double.
*/
static void eb_dbl_projc_imp(eb_t r, const eb_t p) {
fb_t t0, t1;
fb_null(t0);
fb_null(t1);
TRY {
fb_new(t0);
fb_new(t1);
/* t0 = B = x1^2. */
fb_sqr(t0, p->x);
/* C = B + y1. */
fb_add(r->y, t0, p->y);
if (!p->norm) {
/* A = x1 * z1. */
fb_mul(t1, p->x, p->z);
/* z3 = A^2. */
fb_sqr(r->z, t1);
} else {
/* if z1 = 1, A = x1. */
fb_copy(t1, p->x);
/* if z1 = 1, z3 = x1^2. */
fb_copy(r->z, t0);
}
/* t1 = D = A * C. */
fb_mul(t1, t1, r->y);
/* C^2 + D. */
fb_sqr(r->y, r->y);
fb_add(r->x, t1, r->y);
/* C^2 + D + a2 * z3. */
switch (eb_curve_opt_a()) {
case OPT_ZERO:
break;
case OPT_ONE:
fb_add(r->x, r->z, r->x);
break;
case OPT_DIGIT:
fb_mul_dig(r->y, r->z, eb_curve_get_a()[0]);
fb_add(r->x, r->y, r->x);
break;
default:
fb_mul(r->y, r->z, eb_curve_get_a());
fb_add(r->x, r->y, r->x);
break;
}
/* t1 = (D + z3). */
fb_add(t1, t1, r->z);
/* t0 = B^2. */
fb_sqr(t0, t0);
/* t0 = B^2 * z3. */
fb_mul(t0, t0, r->z);
/* y3 = (D + z3) * r3 + B^2 * z3. */
fb_mul(r->y, t1, r->x);
fb_add(r->y, r->y, t0);
r->norm = 0;
}
CATCH_ANY {
THROW(ERR_CAUGHT);
}
FINALLY {
fb_free(t0);
fb_free(t1);
}
}
/**
* Adds two points represented in affine coordinates on an ordinary binary
* elliptic curve.
*
* @param[out] r - the result.
* @param[in] p - the first point to add.
* @param[in] q - the second point to add.
*/
static void eb_add_basic_imp(eb_t r, const eb_t p, const eb_t q) {
fb_t t0, t1, t2;
fb_null(t0);
fb_null(t1);
fb_null(t2);
TRY {
fb_new(t0);
fb_new(t1);
fb_new(t2);
/* t0 = (y1 + y2). */
fb_add(t0, p->y, q->y);
/* t1 = (x1 + x2). */
fb_add(t1, p->x, q->x);
if (fb_is_zero(t1)) {
if (fb_is_zero(t0)) {
/* If t1 is zero and t0 is zero, p = q, should have doubled. */
eb_dbl_basic(r, p);
} else {
/* If t0 is not zero and t1 is zero, q = -p and r = infinity. */
eb_set_infty(r);
}
} else {
/* t2 = 1/(x1 + x2). */
fb_inv(t2, t1);
/* t0 = lambda = (y1 + y2)/(x1 + x2). */
fb_mul(t0, t0, t2);
/* t2 = lambda^2. */
fb_sqr(t2, t0);
/* t2 = lambda^2 + lambda + x1 + x2 + a. */
fb_add(t2, t2, t0);
fb_add(t2, t2, t1);
switch (eb_curve_opt_a()) {
case OPT_ZERO:
break;
case OPT_ONE:
fb_add_dig(t2, t2, (dig_t)1);
break;
case OPT_DIGIT:
fb_add_dig(t2, t2, eb_curve_get_a()[0]);
break;
default:
fb_add(t2, t2, eb_curve_get_a());
break;
}
/* y3 = lambda*(x3 + x1) + x3 + y1. */
fb_add(t1, t2, p->x);
fb_mul(t1, t1, t0);
fb_add(t1, t1, t2);
fb_add(r->y, p->y, t1);
/* x3 = lambda^2 + lambda + x1 + x2 + a. */
fb_copy(r->x, t2);
fb_copy(r->z, p->z);
r->norm = 1;
}
}
CATCH_ANY {
THROW(ERR_CAUGHT);
}
FINALLY {
fb_free(t0);
fb_free(t1);
fb_free(t2);
}
}
/**
* Adds a point represented in affine coordinates to a point represented in
* projective coordinates.
*
* @param[out] r - the result.
* @param[in] p - the affine point.
* @param[in] q - the projective point.
*/
static void eb_add_projc_mix(eb_t r, const eb_t p, const eb_t q) {
fb_t t0, t1, t2, t3, t4, t5;
fb_null(t0);
fb_null(t1);
fb_null(t2);
fb_null(t3);
fb_null(t4);
fb_null(t5);
TRY {
fb_new(t0);
fb_new(t1);
fb_new(t2);
fb_new(t3);
fb_new(t4);
fb_new(t5);
/* madd-2005-dl formulas: 7M + 4S + 9add + 1*4 + 3*2. */
/* http://www.hyperelliptic.org/EFD/g12o/auto-shortw-lopezdahab-1.html#addition-madd-2005-dl */
if (!p->norm) {
/* A = y1 + y2 * z1^2. */
fb_sqr(t0, p->z);
fb_mul(t0, t0, q->y);
fb_add(t0, t0, p->y);
/* B = x1 + x2 * z1. */
fb_mul(t1, p->z, q->x);
fb_add(t1, t1, p->x);
} else {
/* t0 = A = y1 + y2. */
fb_add(t0, p->y, q->y);
/* t1 = B = x1 + x2. */
fb_add(t1, p->x, q->x);
}
if (fb_is_zero(t1)) {
if (fb_is_zero(t0)) {
/* If t0 = 0 and t1 = 0, p = q, should have doubled! */
eb_dbl_projc(r, p);
} else {
/* If t0 = 0, r is infinity. */
eb_set_infty(r);
}
} else {
if (!p->norm) {
/* t2 = C = B * z1. */
fb_mul(t2, p->z, t1);
/* z3 = C^2. */
fb_sqr(r->z, t2);
/* t1 = B^2. */
fb_sqr(t1, t1);
/* t1 = A + B^2. */
fb_add(t1, t0, t1);
} else {
/* If z1 = 0, t2 = C = B. */
fb_copy(t2, t1);
/* z3 = B^2. */
fb_sqr(r->z, t1);
/* t1 = A + z3. */
fb_add(t1, t0, r->z);
}
/* t3 = D = x2 * z3. */
fb_mul(t3, r->z, q->x);
/* t4 = (y2 + x2). */
fb_add(t4, q->x, q->y);
/* z3 = A^2. */
fb_sqr(r->x, t0);
/* t1 = A + B^2 + a2 * C. */
switch (eb_curve_opt_a()) {
case OPT_ZERO:
break;
case OPT_ONE:
fb_add(t1, t1, t2);
break;
case OPT_DIGIT:
/* t5 = a2 * C. */
fb_mul_dig(t5, t2, eb_curve_get_a()[0]);
fb_add(t1, t1, t5);
break;
default:
/* t5 = a2 * C. */
fb_mul(t5, eb_curve_get_a(), t2);
fb_add(t1, t1, t5);
break;
}
/* t1 = C * (A + B^2 + a2 * C). */
fb_mul(t1, t1, t2);
/* x3 = A^2 + C * (A + B^2 + a2 * C). */
fb_add(r->x, r->x, t1);
/* t3 = D + x3. */
fb_add(t3, t3, r->x);
/* t2 = A * B. */
fb_mul(t2, t0, t2);
/* y3 = (D + x3) * (A * B + z3). */
fb_add(r->y, t2, r->z);
fb_mul(r->y, r->y, t3);
/* t0 = z3^2. */
fb_sqr(t0, r->z);
/* t0 = (y2 + x2) * z3^2. */
fb_mul(t0, t0, t4);
/* y3 = (D + x3) * (A * B + z3) + (y2 + x2) * z3^2. */
fb_add(r->y, r->y, t0);
}
r->norm = 0;
}
CATCH_ANY {
THROW(ERR_CAUGHT);
}
FINALLY {
fb_free(t0);
fb_free(t1);
fb_free(t2);
fb_free(t3);
fb_free(t4);
fb_free(t5);
}
}
