diff --git a/src/field.h b/src/field.h index bb99f948e..c1775912f 100644 --- a/src/field.h +++ b/src/field.h @@ -352,4 +352,7 @@ static int secp256k1_fe_is_square_var(const secp256k1_fe *a); /** Check invariants on a field element (no-op unless VERIFY is enabled). */ static void secp256k1_fe_verify(const secp256k1_fe *a); +/** Check that magnitude of a is at most m (no-op unless VERIFY is enabled). */ +static void secp256k1_fe_verify_magnitude(const secp256k1_fe *a, int m); + #endif /* SECP256K1_FIELD_H */ diff --git a/src/field_impl.h b/src/field_impl.h index 7f18ebdc9..29b54c74b 100644 --- a/src/field_impl.h +++ b/src/field_impl.h @@ -23,8 +23,8 @@ SECP256K1_INLINE static int secp256k1_fe_equal(const secp256k1_fe *a, const secp #ifdef VERIFY secp256k1_fe_verify(a); secp256k1_fe_verify(b); - VERIFY_CHECK(a->magnitude <= 1); - VERIFY_CHECK(b->magnitude <= 31); + secp256k1_fe_verify_magnitude(a, 1); + secp256k1_fe_verify_magnitude(b, 31); #endif secp256k1_fe_negate(&na, a, 1); secp256k1_fe_add(&na, b); @@ -36,8 +36,8 @@ SECP256K1_INLINE static int secp256k1_fe_equal_var(const secp256k1_fe *a, const #ifdef VERIFY secp256k1_fe_verify(a); secp256k1_fe_verify(b); - VERIFY_CHECK(a->magnitude <= 1); - VERIFY_CHECK(b->magnitude <= 31); + secp256k1_fe_verify_magnitude(a, 1); + secp256k1_fe_verify_magnitude(b, 31); #endif secp256k1_fe_negate(&na, a, 1); secp256k1_fe_add(&na, b); @@ -60,7 +60,7 @@ static int secp256k1_fe_sqrt(secp256k1_fe * SECP256K1_RESTRICT r, const secp256k #ifdef VERIFY VERIFY_CHECK(r != a); secp256k1_fe_verify(a); - VERIFY_CHECK(a->magnitude <= 8); + secp256k1_fe_verify_magnitude(a, 8); #endif /** The binary representation of (p + 1)/4 has 3 blocks of 1s, with lengths in @@ -159,19 +159,26 @@ static int secp256k1_fe_sqrt(secp256k1_fe * SECP256K1_RESTRICT r, const secp256k #ifndef VERIFY static void secp256k1_fe_verify(const secp256k1_fe *a) { (void)a; } +static void secp256k1_fe_verify_magnitude(const secp256k1_fe *a, int m) { (void)a; (void)m; } #else static void secp256k1_fe_impl_verify(const secp256k1_fe *a); static void secp256k1_fe_verify(const secp256k1_fe *a) { /* Magnitude between 0 and 32. */ - VERIFY_CHECK((a->magnitude >= 0) && (a->magnitude <= 32)); + secp256k1_fe_verify_magnitude(a, 32); /* Normalized is 0 or 1. */ VERIFY_CHECK((a->normalized == 0) || (a->normalized == 1)); /* If normalized, magnitude must be 0 or 1. */ - if (a->normalized) VERIFY_CHECK(a->magnitude <= 1); + if (a->normalized) secp256k1_fe_verify_magnitude(a, 1); /* Invoke implementation-specific checks. */ secp256k1_fe_impl_verify(a); } +static void secp256k1_fe_verify_magnitude(const secp256k1_fe *a, int m) { + VERIFY_CHECK(m >= 0); + VERIFY_CHECK(m <= 32); + VERIFY_CHECK(a->magnitude <= m); +} + static void secp256k1_fe_impl_normalize(secp256k1_fe *r); SECP256K1_INLINE static void secp256k1_fe_normalize(secp256k1_fe *r) { secp256k1_fe_verify(r); @@ -293,7 +300,7 @@ static void secp256k1_fe_impl_negate_unchecked(secp256k1_fe *r, const secp256k1_ SECP256K1_INLINE static void secp256k1_fe_negate_unchecked(secp256k1_fe *r, const secp256k1_fe *a, int m) { secp256k1_fe_verify(a); VERIFY_CHECK(m >= 0 && m <= 31); - VERIFY_CHECK(a->magnitude <= m); + secp256k1_fe_verify_magnitude(a, m); secp256k1_fe_impl_negate_unchecked(r, a, m); r->magnitude = m + 1; r->normalized = 0; @@ -326,8 +333,8 @@ static void secp256k1_fe_impl_mul(secp256k1_fe *r, const secp256k1_fe *a, const SECP256K1_INLINE static void secp256k1_fe_mul(secp256k1_fe *r, const secp256k1_fe *a, const secp256k1_fe * SECP256K1_RESTRICT b) { secp256k1_fe_verify(a); secp256k1_fe_verify(b); - VERIFY_CHECK(a->magnitude <= 8); - VERIFY_CHECK(b->magnitude <= 8); + secp256k1_fe_verify_magnitude(a, 8); + secp256k1_fe_verify_magnitude(b, 8); VERIFY_CHECK(r != b); VERIFY_CHECK(a != b); secp256k1_fe_impl_mul(r, a, b); @@ -339,7 +346,7 @@ SECP256K1_INLINE static void secp256k1_fe_mul(secp256k1_fe *r, const secp256k1_f static void secp256k1_fe_impl_sqr(secp256k1_fe *r, const secp256k1_fe *a); SECP256K1_INLINE static void secp256k1_fe_sqr(secp256k1_fe *r, const secp256k1_fe *a) { secp256k1_fe_verify(a); - VERIFY_CHECK(a->magnitude <= 8); + secp256k1_fe_verify_magnitude(a, 8); secp256k1_fe_impl_sqr(r, a); r->magnitude = 1; r->normalized = 0; @@ -418,7 +425,7 @@ SECP256K1_INLINE static void secp256k1_fe_get_bounds(secp256k1_fe* r, int m) { static void secp256k1_fe_impl_half(secp256k1_fe *r); SECP256K1_INLINE static void secp256k1_fe_half(secp256k1_fe *r) { secp256k1_fe_verify(r); - VERIFY_CHECK(r->magnitude < 32); + secp256k1_fe_verify_magnitude(r, 31); secp256k1_fe_impl_half(r); r->magnitude = (r->magnitude >> 1) + 1; r->normalized = 0; diff --git a/src/group.h b/src/group.h index 1cc613716..86eb9e1f8 100644 --- a/src/group.h +++ b/src/group.h @@ -44,6 +44,14 @@ typedef struct { #define SECP256K1_GE_STORAGE_CONST_GET(t) SECP256K1_FE_STORAGE_CONST_GET(t.x), SECP256K1_FE_STORAGE_CONST_GET(t.y) +/** Maximum allowed magnitudes for group element coordinates + * in affine (x, y) and jacobian (x, y, z) representation. */ +#define SECP256K1_GE_X_MAGNITUDE_MAX 4 +#define SECP256K1_GE_Y_MAGNITUDE_MAX 3 +#define SECP256K1_GEJ_X_MAGNITUDE_MAX 4 +#define SECP256K1_GEJ_Y_MAGNITUDE_MAX 4 +#define SECP256K1_GEJ_Z_MAGNITUDE_MAX 1 + /** Set a group element equal to the point with given X and Y coordinates */ static void secp256k1_ge_set_xy(secp256k1_ge *r, const secp256k1_fe *x, const secp256k1_fe *y); diff --git a/src/group_impl.h b/src/group_impl.h index ffdfeaa10..dd8a5d0ca 100644 --- a/src/group_impl.h +++ b/src/group_impl.h @@ -77,6 +77,8 @@ static void secp256k1_ge_verify(const secp256k1_ge *a) { #ifdef VERIFY secp256k1_fe_verify(&a->x); secp256k1_fe_verify(&a->y); + secp256k1_fe_verify_magnitude(&a->x, SECP256K1_GE_X_MAGNITUDE_MAX); + secp256k1_fe_verify_magnitude(&a->y, SECP256K1_GE_Y_MAGNITUDE_MAX); VERIFY_CHECK(a->infinity == 0 || a->infinity == 1); #endif (void)a; @@ -87,6 +89,9 @@ static void secp256k1_gej_verify(const secp256k1_gej *a) { secp256k1_fe_verify(&a->x); secp256k1_fe_verify(&a->y); secp256k1_fe_verify(&a->z); + secp256k1_fe_verify_magnitude(&a->x, SECP256K1_GEJ_X_MAGNITUDE_MAX); + secp256k1_fe_verify_magnitude(&a->y, SECP256K1_GEJ_Y_MAGNITUDE_MAX); + secp256k1_fe_verify_magnitude(&a->z, SECP256K1_GEJ_Z_MAGNITUDE_MAX); VERIFY_CHECK(a->infinity == 0 || a->infinity == 1); #endif (void)a; @@ -99,11 +104,13 @@ static void secp256k1_ge_set_gej_zinv(secp256k1_ge *r, const secp256k1_gej *a, c secp256k1_gej_verify(a); secp256k1_fe_verify(zi); VERIFY_CHECK(!a->infinity); + secp256k1_fe_sqr(&zi2, zi); secp256k1_fe_mul(&zi3, &zi2, zi); secp256k1_fe_mul(&r->x, &a->x, &zi2); secp256k1_fe_mul(&r->y, &a->y, &zi3); r->infinity = a->infinity; + secp256k1_ge_verify(r); } @@ -114,39 +121,47 @@ static void secp256k1_ge_set_ge_zinv(secp256k1_ge *r, const secp256k1_ge *a, con secp256k1_ge_verify(a); secp256k1_fe_verify(zi); VERIFY_CHECK(!a->infinity); + secp256k1_fe_sqr(&zi2, zi); secp256k1_fe_mul(&zi3, &zi2, zi); secp256k1_fe_mul(&r->x, &a->x, &zi2); secp256k1_fe_mul(&r->y, &a->y, &zi3); r->infinity = a->infinity; + secp256k1_ge_verify(r); } static void secp256k1_ge_set_xy(secp256k1_ge *r, const secp256k1_fe *x, const secp256k1_fe *y) { secp256k1_fe_verify(x); secp256k1_fe_verify(y); + r->infinity = 0; r->x = *x; r->y = *y; + secp256k1_ge_verify(r); } static int secp256k1_ge_is_infinity(const secp256k1_ge *a) { secp256k1_ge_verify(a); + return a->infinity; } static void secp256k1_ge_neg(secp256k1_ge *r, const secp256k1_ge *a) { secp256k1_ge_verify(a); + *r = *a; secp256k1_fe_normalize_weak(&r->y); secp256k1_fe_negate(&r->y, &r->y, 1); + secp256k1_ge_verify(r); } static void secp256k1_ge_set_gej(secp256k1_ge *r, secp256k1_gej *a) { secp256k1_fe z2, z3; secp256k1_gej_verify(a); + r->infinity = a->infinity; secp256k1_fe_inv(&a->z, &a->z); secp256k1_fe_sqr(&z2, &a->z); @@ -156,12 +171,15 @@ static void secp256k1_ge_set_gej(secp256k1_ge *r, secp256k1_gej *a) { secp256k1_fe_set_int(&a->z, 1); r->x = a->x; r->y = a->y; + + secp256k1_gej_verify(a); secp256k1_ge_verify(r); } static void secp256k1_ge_set_gej_var(secp256k1_ge *r, secp256k1_gej *a) { secp256k1_fe z2, z3; secp256k1_gej_verify(a); + if (secp256k1_gej_is_infinity(a)) { secp256k1_ge_set_infinity(r); return; @@ -174,6 +192,8 @@ static void secp256k1_ge_set_gej_var(secp256k1_ge *r, secp256k1_gej *a) { secp256k1_fe_mul(&a->y, &a->y, &z3); secp256k1_fe_set_int(&a->z, 1); secp256k1_ge_set_xy(r, &a->x, &a->y); + + secp256k1_gej_verify(a); secp256k1_ge_verify(r); } @@ -181,9 +201,13 @@ static void secp256k1_ge_set_all_gej_var(secp256k1_ge *r, const secp256k1_gej *a secp256k1_fe u; size_t i; size_t last_i = SIZE_MAX; - +#ifdef VERIFY for (i = 0; i < len; i++) { secp256k1_gej_verify(&a[i]); + } +#endif + + for (i = 0; i < len; i++) { if (a[i].infinity) { secp256k1_ge_set_infinity(&r[i]); } else { @@ -217,36 +241,46 @@ static void secp256k1_ge_set_all_gej_var(secp256k1_ge *r, const secp256k1_gej *a if (!a[i].infinity) { secp256k1_ge_set_gej_zinv(&r[i], &a[i], &r[i].x); } + } + +#ifdef VERIFY + for (i = 0; i < len; i++) { secp256k1_ge_verify(&r[i]); } +#endif } static void secp256k1_ge_table_set_globalz(size_t len, secp256k1_ge *a, const secp256k1_fe *zr) { - size_t i = len - 1; + size_t i; secp256k1_fe zs; - - if (len > 0) { - /* Verify inputs a[len-1] and zr[len-1]. */ +#ifdef VERIFY + for (i = 0; i < len; i++) { secp256k1_ge_verify(&a[i]); secp256k1_fe_verify(&zr[i]); + } +#endif + + if (len > 0) { + i = len - 1; /* Ensure all y values are in weak normal form for fast negation of points */ secp256k1_fe_normalize_weak(&a[i].y); zs = zr[i]; /* Work our way backwards, using the z-ratios to scale the x/y values. */ while (i > 0) { - /* Verify all inputs a[i] and zr[i]. */ - secp256k1_fe_verify(&zr[i]); - secp256k1_ge_verify(&a[i]); if (i != len - 1) { secp256k1_fe_mul(&zs, &zs, &zr[i]); } i--; secp256k1_ge_set_ge_zinv(&a[i], &a[i], &zs); - /* Verify the output a[i]. */ - secp256k1_ge_verify(&a[i]); } } + +#ifdef VERIFY + for (i = 0; i < len; i++) { + secp256k1_ge_verify(&a[i]); + } +#endif } static void secp256k1_gej_set_infinity(secp256k1_gej *r) { @@ -254,6 +288,7 @@ static void secp256k1_gej_set_infinity(secp256k1_gej *r) { secp256k1_fe_clear(&r->x); secp256k1_fe_clear(&r->y); secp256k1_fe_clear(&r->z); + secp256k1_gej_verify(r); } @@ -261,6 +296,7 @@ static void secp256k1_ge_set_infinity(secp256k1_ge *r) { r->infinity = 1; secp256k1_fe_clear(&r->x); secp256k1_fe_clear(&r->y); + secp256k1_ge_verify(r); } @@ -269,18 +305,23 @@ static void secp256k1_gej_clear(secp256k1_gej *r) { secp256k1_fe_clear(&r->x); secp256k1_fe_clear(&r->y); secp256k1_fe_clear(&r->z); + + secp256k1_gej_verify(r); } static void secp256k1_ge_clear(secp256k1_ge *r) { r->infinity = 0; secp256k1_fe_clear(&r->x); secp256k1_fe_clear(&r->y); + + secp256k1_ge_verify(r); } static int secp256k1_ge_set_xo_var(secp256k1_ge *r, const secp256k1_fe *x, int odd) { secp256k1_fe x2, x3; int ret; secp256k1_fe_verify(x); + r->x = *x; secp256k1_fe_sqr(&x2, x); secp256k1_fe_mul(&x3, x, &x2); @@ -291,16 +332,19 @@ static int secp256k1_ge_set_xo_var(secp256k1_ge *r, const secp256k1_fe *x, int o if (secp256k1_fe_is_odd(&r->y) != odd) { secp256k1_fe_negate(&r->y, &r->y, 1); } + secp256k1_ge_verify(r); return ret; } static void secp256k1_gej_set_ge(secp256k1_gej *r, const secp256k1_ge *a) { secp256k1_ge_verify(a); + r->infinity = a->infinity; r->x = a->x; r->y = a->y; secp256k1_fe_set_int(&r->z, 1); + secp256k1_gej_verify(r); } @@ -308,6 +352,7 @@ static int secp256k1_gej_eq_var(const secp256k1_gej *a, const secp256k1_gej *b) secp256k1_gej tmp; secp256k1_gej_verify(b); secp256k1_gej_verify(a); + secp256k1_gej_neg(&tmp, a); secp256k1_gej_add_var(&tmp, &tmp, b, NULL); return secp256k1_gej_is_infinity(&tmp); @@ -315,11 +360,9 @@ static int secp256k1_gej_eq_var(const secp256k1_gej *a, const secp256k1_gej *b) static int secp256k1_gej_eq_x_var(const secp256k1_fe *x, const secp256k1_gej *a) { secp256k1_fe r; - -#ifdef VERIFY secp256k1_fe_verify(x); - VERIFY_CHECK(a->x.magnitude <= 31); secp256k1_gej_verify(a); +#ifdef VERIFY VERIFY_CHECK(!a->infinity); #endif @@ -329,23 +372,27 @@ static int secp256k1_gej_eq_x_var(const secp256k1_fe *x, const secp256k1_gej *a) static void secp256k1_gej_neg(secp256k1_gej *r, const secp256k1_gej *a) { secp256k1_gej_verify(a); + r->infinity = a->infinity; r->x = a->x; r->y = a->y; r->z = a->z; secp256k1_fe_normalize_weak(&r->y); secp256k1_fe_negate(&r->y, &r->y, 1); + secp256k1_gej_verify(r); } static int secp256k1_gej_is_infinity(const secp256k1_gej *a) { secp256k1_gej_verify(a); + return a->infinity; } static int secp256k1_ge_is_valid_var(const secp256k1_ge *a) { secp256k1_fe y2, x3; secp256k1_ge_verify(a); + if (a->infinity) { return 0; } @@ -359,8 +406,8 @@ static int secp256k1_ge_is_valid_var(const secp256k1_ge *a) { static SECP256K1_INLINE void secp256k1_gej_double(secp256k1_gej *r, const secp256k1_gej *a) { /* Operations: 3 mul, 4 sqr, 8 add/half/mul_int/negate */ secp256k1_fe l, s, t; - secp256k1_gej_verify(a); + r->infinity = a->infinity; /* Formula used: @@ -387,10 +434,13 @@ static SECP256K1_INLINE void secp256k1_gej_double(secp256k1_gej *r, const secp25 secp256k1_fe_mul(&r->y, &t, &l); /* Y3 = L*(X3 + T) (1) */ secp256k1_fe_add(&r->y, &s); /* Y3 = L*(X3 + T) + S^2 (2) */ secp256k1_fe_negate(&r->y, &r->y, 2); /* Y3 = -(L*(X3 + T) + S^2) (3) */ + secp256k1_gej_verify(r); } static void secp256k1_gej_double_var(secp256k1_gej *r, const secp256k1_gej *a, secp256k1_fe *rzr) { + secp256k1_gej_verify(a); + /** For secp256k1, 2Q is infinity if and only if Q is infinity. This is because if 2Q = infinity, * Q must equal -Q, or that Q.y == -(Q.y), or Q.y is 0. For a point on y^2 = x^3 + 7 to have * y=0, x^3 must be -7 mod p. However, -7 has no cube root mod p. @@ -401,7 +451,6 @@ static void secp256k1_gej_double_var(secp256k1_gej *r, const secp256k1_gej *a, s * the infinity flag even though the point doubles to infinity, and the result * point will be gibberish (z = 0 but infinity = 0). */ - secp256k1_gej_verify(a); if (a->infinity) { secp256k1_gej_set_infinity(r); if (rzr != NULL) { @@ -416,15 +465,16 @@ static void secp256k1_gej_double_var(secp256k1_gej *r, const secp256k1_gej *a, s } secp256k1_gej_double(r, a); + secp256k1_gej_verify(r); } static void secp256k1_gej_add_var(secp256k1_gej *r, const secp256k1_gej *a, const secp256k1_gej *b, secp256k1_fe *rzr) { /* 12 mul, 4 sqr, 11 add/negate/normalizes_to_zero (ignoring special cases) */ secp256k1_fe z22, z12, u1, u2, s1, s2, h, i, h2, h3, t; - secp256k1_gej_verify(a); secp256k1_gej_verify(b); + if (a->infinity) { VERIFY_CHECK(rzr == NULL); *r = *b; @@ -479,14 +529,16 @@ static void secp256k1_gej_add_var(secp256k1_gej *r, const secp256k1_gej *a, cons secp256k1_fe_mul(&r->y, &t, &i); secp256k1_fe_mul(&h3, &h3, &s1); secp256k1_fe_add(&r->y, &h3); + secp256k1_gej_verify(r); } static void secp256k1_gej_add_ge_var(secp256k1_gej *r, const secp256k1_gej *a, const secp256k1_ge *b, secp256k1_fe *rzr) { - /* 8 mul, 3 sqr, 13 add/negate/normalize_weak/normalizes_to_zero (ignoring special cases) */ + /* Operations: 8 mul, 3 sqr, 11 add/negate/normalizes_to_zero (ignoring special cases) */ secp256k1_fe z12, u1, u2, s1, s2, h, i, h2, h3, t; secp256k1_gej_verify(a); secp256k1_ge_verify(b); + if (a->infinity) { VERIFY_CHECK(rzr == NULL); secp256k1_gej_set_ge(r, b); @@ -501,11 +553,11 @@ static void secp256k1_gej_add_ge_var(secp256k1_gej *r, const secp256k1_gej *a, c } secp256k1_fe_sqr(&z12, &a->z); - u1 = a->x; secp256k1_fe_normalize_weak(&u1); + u1 = a->x; secp256k1_fe_mul(&u2, &b->x, &z12); - s1 = a->y; secp256k1_fe_normalize_weak(&s1); + s1 = a->y; secp256k1_fe_mul(&s2, &b->y, &z12); secp256k1_fe_mul(&s2, &s2, &a->z); - secp256k1_fe_negate(&h, &u1, 1); secp256k1_fe_add(&h, &u2); + secp256k1_fe_negate(&h, &u1, SECP256K1_GEJ_X_MAGNITUDE_MAX); secp256k1_fe_add(&h, &u2); secp256k1_fe_negate(&i, &s2, 1); secp256k1_fe_add(&i, &s1); if (secp256k1_fe_normalizes_to_zero_var(&h)) { if (secp256k1_fe_normalizes_to_zero_var(&i)) { @@ -539,16 +591,18 @@ static void secp256k1_gej_add_ge_var(secp256k1_gej *r, const secp256k1_gej *a, c secp256k1_fe_mul(&r->y, &t, &i); secp256k1_fe_mul(&h3, &h3, &s1); secp256k1_fe_add(&r->y, &h3); + secp256k1_gej_verify(r); if (rzr != NULL) secp256k1_fe_verify(rzr); } static void secp256k1_gej_add_zinv_var(secp256k1_gej *r, const secp256k1_gej *a, const secp256k1_ge *b, const secp256k1_fe *bzinv) { - /* 9 mul, 3 sqr, 13 add/negate/normalize_weak/normalizes_to_zero (ignoring special cases) */ + /* Operations: 9 mul, 3 sqr, 11 add/negate/normalizes_to_zero (ignoring special cases) */ secp256k1_fe az, z12, u1, u2, s1, s2, h, i, h2, h3, t; - + secp256k1_gej_verify(a); secp256k1_ge_verify(b); secp256k1_fe_verify(bzinv); + if (a->infinity) { secp256k1_fe bzinv2, bzinv3; r->infinity = b->infinity; @@ -557,6 +611,7 @@ static void secp256k1_gej_add_zinv_var(secp256k1_gej *r, const secp256k1_gej *a, secp256k1_fe_mul(&r->x, &b->x, &bzinv2); secp256k1_fe_mul(&r->y, &b->y, &bzinv3); secp256k1_fe_set_int(&r->z, 1); + secp256k1_gej_verify(r); return; } if (b->infinity) { @@ -575,11 +630,11 @@ static void secp256k1_gej_add_zinv_var(secp256k1_gej *r, const secp256k1_gej *a, secp256k1_fe_mul(&az, &a->z, bzinv); secp256k1_fe_sqr(&z12, &az); - u1 = a->x; secp256k1_fe_normalize_weak(&u1); + u1 = a->x; secp256k1_fe_mul(&u2, &b->x, &z12); - s1 = a->y; secp256k1_fe_normalize_weak(&s1); + s1 = a->y; secp256k1_fe_mul(&s2, &b->y, &z12); secp256k1_fe_mul(&s2, &s2, &az); - secp256k1_fe_negate(&h, &u1, 1); secp256k1_fe_add(&h, &u2); + secp256k1_fe_negate(&h, &u1, SECP256K1_GEJ_X_MAGNITUDE_MAX); secp256k1_fe_add(&h, &u2); secp256k1_fe_negate(&i, &s2, 1); secp256k1_fe_add(&i, &s1); if (secp256k1_fe_normalizes_to_zero_var(&h)) { if (secp256k1_fe_normalizes_to_zero_var(&i)) { @@ -607,19 +662,19 @@ static void secp256k1_gej_add_zinv_var(secp256k1_gej *r, const secp256k1_gej *a, secp256k1_fe_mul(&r->y, &t, &i); secp256k1_fe_mul(&h3, &h3, &s1); secp256k1_fe_add(&r->y, &h3); + secp256k1_gej_verify(r); } static void secp256k1_gej_add_ge(secp256k1_gej *r, const secp256k1_gej *a, const secp256k1_ge *b) { - /* Operations: 7 mul, 5 sqr, 24 add/cmov/half/mul_int/negate/normalize_weak/normalizes_to_zero */ + /* Operations: 7 mul, 5 sqr, 21 add/cmov/half/mul_int/negate/normalizes_to_zero */ secp256k1_fe zz, u1, u2, s1, s2, t, tt, m, n, q, rr; secp256k1_fe m_alt, rr_alt; int degenerate; secp256k1_gej_verify(a); secp256k1_ge_verify(b); VERIFY_CHECK(!b->infinity); - VERIFY_CHECK(a->infinity == 0 || a->infinity == 1); /* In: * Eric Brier and Marc Joye, Weierstrass Elliptic Curves and Side-Channel Attacks. @@ -672,17 +727,17 @@ static void secp256k1_gej_add_ge(secp256k1_gej *r, const secp256k1_gej *a, const */ secp256k1_fe_sqr(&zz, &a->z); /* z = Z1^2 */ - u1 = a->x; secp256k1_fe_normalize_weak(&u1); /* u1 = U1 = X1*Z2^2 (1) */ + u1 = a->x; /* u1 = U1 = X1*Z2^2 (GEJ_X_M) */ secp256k1_fe_mul(&u2, &b->x, &zz); /* u2 = U2 = X2*Z1^2 (1) */ - s1 = a->y; secp256k1_fe_normalize_weak(&s1); /* s1 = S1 = Y1*Z2^3 (1) */ + s1 = a->y; /* s1 = S1 = Y1*Z2^3 (GEJ_Y_M) */ secp256k1_fe_mul(&s2, &b->y, &zz); /* s2 = Y2*Z1^2 (1) */ secp256k1_fe_mul(&s2, &s2, &a->z); /* s2 = S2 = Y2*Z1^3 (1) */ - t = u1; secp256k1_fe_add(&t, &u2); /* t = T = U1+U2 (2) */ - m = s1; secp256k1_fe_add(&m, &s2); /* m = M = S1+S2 (2) */ + t = u1; secp256k1_fe_add(&t, &u2); /* t = T = U1+U2 (GEJ_X_M+1) */ + m = s1; secp256k1_fe_add(&m, &s2); /* m = M = S1+S2 (GEJ_Y_M+1) */ secp256k1_fe_sqr(&rr, &t); /* rr = T^2 (1) */ - secp256k1_fe_negate(&m_alt, &u2, 1); /* Malt = -X2*Z1^2 */ - secp256k1_fe_mul(&tt, &u1, &m_alt); /* tt = -U1*U2 (2) */ - secp256k1_fe_add(&rr, &tt); /* rr = R = T^2-U1*U2 (3) */ + secp256k1_fe_negate(&m_alt, &u2, 1); /* Malt = -X2*Z1^2 (2) */ + secp256k1_fe_mul(&tt, &u1, &m_alt); /* tt = -U1*U2 (1) */ + secp256k1_fe_add(&rr, &tt); /* rr = R = T^2-U1*U2 (2) */ /* If lambda = R/M = R/0 we have a problem (except in the "trivial" * case that Z = z1z2 = 0, and this is special-cased later on). */ degenerate = secp256k1_fe_normalizes_to_zero(&m); @@ -692,24 +747,25 @@ static void secp256k1_gej_add_ge(secp256k1_gej *r, const secp256k1_gej *a, const * non-indeterminate expression for lambda is (y1 - y2)/(x1 - x2), * so we set R/M equal to this. */ rr_alt = s1; - secp256k1_fe_mul_int(&rr_alt, 2); /* rr = Y1*Z2^3 - Y2*Z1^3 (2) */ - secp256k1_fe_add(&m_alt, &u1); /* Malt = X1*Z2^2 - X2*Z1^2 */ + secp256k1_fe_mul_int(&rr_alt, 2); /* rr_alt = Y1*Z2^3 - Y2*Z1^3 (GEJ_Y_M*2) */ + secp256k1_fe_add(&m_alt, &u1); /* Malt = X1*Z2^2 - X2*Z1^2 (GEJ_X_M+2) */ - secp256k1_fe_cmov(&rr_alt, &rr, !degenerate); - secp256k1_fe_cmov(&m_alt, &m, !degenerate); + secp256k1_fe_cmov(&rr_alt, &rr, !degenerate); /* rr_alt (GEJ_Y_M*2) */ + secp256k1_fe_cmov(&m_alt, &m, !degenerate); /* m_alt (GEJ_X_M+2) */ /* Now Ralt / Malt = lambda and is guaranteed not to be Ralt / 0. * From here on out Ralt and Malt represent the numerator * and denominator of lambda; R and M represent the explicit * expressions x1^2 + x2^2 + x1x2 and y1 + y2. */ secp256k1_fe_sqr(&n, &m_alt); /* n = Malt^2 (1) */ - secp256k1_fe_negate(&q, &t, 2); /* q = -T (3) */ + secp256k1_fe_negate(&q, &t, + SECP256K1_GEJ_X_MAGNITUDE_MAX + 1); /* q = -T (GEJ_X_M+2) */ secp256k1_fe_mul(&q, &q, &n); /* q = Q = -T*Malt^2 (1) */ /* These two lines use the observation that either M == Malt or M == 0, * so M^3 * Malt is either Malt^4 (which is computed by squaring), or * zero (which is "computed" by cmov). So the cost is one squaring * versus two multiplications. */ - secp256k1_fe_sqr(&n, &n); - secp256k1_fe_cmov(&n, &m, degenerate); /* n = M^3 * Malt (2) */ + secp256k1_fe_sqr(&n, &n); /* n = Malt^4 (1) */ + secp256k1_fe_cmov(&n, &m, degenerate); /* n = M^3 * Malt (GEJ_Y_M+1) */ secp256k1_fe_sqr(&t, &rr_alt); /* t = Ralt^2 (1) */ secp256k1_fe_mul(&r->z, &a->z, &m_alt); /* r->z = Z3 = Malt*Z (1) */ secp256k1_fe_add(&t, &q); /* t = Ralt^2 + Q (2) */ @@ -717,9 +773,10 @@ static void secp256k1_gej_add_ge(secp256k1_gej *r, const secp256k1_gej *a, const secp256k1_fe_mul_int(&t, 2); /* t = 2*X3 (4) */ secp256k1_fe_add(&t, &q); /* t = 2*X3 + Q (5) */ secp256k1_fe_mul(&t, &t, &rr_alt); /* t = Ralt*(2*X3 + Q) (1) */ - secp256k1_fe_add(&t, &n); /* t = Ralt*(2*X3 + Q) + M^3*Malt (3) */ - secp256k1_fe_negate(&r->y, &t, 3); /* r->y = -(Ralt*(2*X3 + Q) + M^3*Malt) (4) */ - secp256k1_fe_half(&r->y); /* r->y = Y3 = -(Ralt*(2*X3 + Q) + M^3*Malt)/2 (3) */ + secp256k1_fe_add(&t, &n); /* t = Ralt*(2*X3 + Q) + M^3*Malt (GEJ_Y_M+2) */ + secp256k1_fe_negate(&r->y, &t, + SECP256K1_GEJ_Y_MAGNITUDE_MAX + 2); /* r->y = -(Ralt*(2*X3 + Q) + M^3*Malt) (GEJ_Y_M+3) */ + secp256k1_fe_half(&r->y); /* r->y = Y3 = -(Ralt*(2*X3 + Q) + M^3*Malt)/2 ((GEJ_Y_M+3)/2 + 1) */ /* In case a->infinity == 1, replace r with (b->x, b->y, 1). */ secp256k1_fe_cmov(&r->x, &b->x, a->infinity); @@ -743,6 +800,7 @@ static void secp256k1_gej_add_ge(secp256k1_gej *r, const secp256k1_gej *a, const * We have degenerate = false, r->z = (y1 + y2) * Z. * Then r->infinity = ((y1 + y2)Z == 0) = (y1 == -y2) = false. */ r->infinity = secp256k1_fe_normalizes_to_zero(&r->z); + secp256k1_gej_verify(r); } @@ -754,11 +812,13 @@ static void secp256k1_gej_rescale(secp256k1_gej *r, const secp256k1_fe *s) { #ifdef VERIFY VERIFY_CHECK(!secp256k1_fe_normalizes_to_zero_var(s)); #endif + secp256k1_fe_sqr(&zz, s); secp256k1_fe_mul(&r->x, &r->x, &zz); /* r->x *= s^2 */ secp256k1_fe_mul(&r->y, &r->y, &zz); secp256k1_fe_mul(&r->y, &r->y, s); /* r->y *= s^3 */ secp256k1_fe_mul(&r->z, &r->z, s); /* r->z *= s */ + secp256k1_gej_verify(r); } @@ -766,6 +826,7 @@ static void secp256k1_ge_to_storage(secp256k1_ge_storage *r, const secp256k1_ge secp256k1_fe x, y; secp256k1_ge_verify(a); VERIFY_CHECK(!a->infinity); + x = a->x; secp256k1_fe_normalize(&x); y = a->y; @@ -778,17 +839,19 @@ static void secp256k1_ge_from_storage(secp256k1_ge *r, const secp256k1_ge_storag secp256k1_fe_from_storage(&r->x, &a->x); secp256k1_fe_from_storage(&r->y, &a->y); r->infinity = 0; + secp256k1_ge_verify(r); } static SECP256K1_INLINE void secp256k1_gej_cmov(secp256k1_gej *r, const secp256k1_gej *a, int flag) { secp256k1_gej_verify(r); secp256k1_gej_verify(a); + secp256k1_fe_cmov(&r->x, &a->x, flag); secp256k1_fe_cmov(&r->y, &a->y, flag); secp256k1_fe_cmov(&r->z, &a->z, flag); - r->infinity ^= (r->infinity ^ a->infinity) & flag; + secp256k1_gej_verify(r); } @@ -798,9 +861,11 @@ static SECP256K1_INLINE void secp256k1_ge_storage_cmov(secp256k1_ge_storage *r, } static void secp256k1_ge_mul_lambda(secp256k1_ge *r, const secp256k1_ge *a) { - *r = *a; secp256k1_ge_verify(a); + + *r = *a; secp256k1_fe_mul(&r->x, &r->x, &secp256k1_const_beta); + secp256k1_ge_verify(r); } @@ -808,8 +873,8 @@ static int secp256k1_ge_is_in_correct_subgroup(const secp256k1_ge* ge) { #ifdef EXHAUSTIVE_TEST_ORDER secp256k1_gej out; int i; - secp256k1_ge_verify(ge); + /* A very simple EC multiplication ladder that avoids a dependency on ecmult. */ secp256k1_gej_set_infinity(&out); for (i = 0; i < 32; ++i) { @@ -820,6 +885,8 @@ static int secp256k1_ge_is_in_correct_subgroup(const secp256k1_ge* ge) { } return secp256k1_gej_is_infinity(&out); #else + secp256k1_ge_verify(ge); + (void)ge; /* The real secp256k1 group has cofactor 1, so the subgroup is the entire curve. */ return 1; diff --git a/src/tests.c b/src/tests.c index f08b61c84..7a76b27ae 100644 --- a/src/tests.c +++ b/src/tests.c @@ -89,9 +89,9 @@ static void uncounting_illegal_callback_fn(const char* str, void* data) { (*p)--; } -static void random_field_element_magnitude(secp256k1_fe *fe) { +static void random_field_element_magnitude(secp256k1_fe *fe, int m) { secp256k1_fe zero; - int n = secp256k1_testrand_int(9); + int n = secp256k1_testrand_int(m + 1); secp256k1_fe_normalize(fe); if (n == 0) { return; @@ -121,6 +121,30 @@ static void random_fe_non_zero_test(secp256k1_fe *fe) { } while(secp256k1_fe_is_zero(fe)); } +static void random_fe_magnitude(secp256k1_fe *fe) { + random_field_element_magnitude(fe, 8); +} + +static void random_ge_x_magnitude(secp256k1_ge *ge) { + random_field_element_magnitude(&ge->x, SECP256K1_GE_X_MAGNITUDE_MAX); +} + +static void random_ge_y_magnitude(secp256k1_ge *ge) { + random_field_element_magnitude(&ge->y, SECP256K1_GE_Y_MAGNITUDE_MAX); +} + +static void random_gej_x_magnitude(secp256k1_gej *gej) { + random_field_element_magnitude(&gej->x, SECP256K1_GEJ_X_MAGNITUDE_MAX); +} + +static void random_gej_y_magnitude(secp256k1_gej *gej) { + random_field_element_magnitude(&gej->y, SECP256K1_GEJ_Y_MAGNITUDE_MAX); +} + +static void random_gej_z_magnitude(secp256k1_gej *gej) { + random_field_element_magnitude(&gej->z, SECP256K1_GEJ_Z_MAGNITUDE_MAX); +} + static void random_group_element_test(secp256k1_ge *ge) { secp256k1_fe fe; do { @@ -3279,13 +3303,13 @@ static void run_fe_mul(void) { for (i = 0; i < 100 * COUNT; ++i) { secp256k1_fe a, b, c, d; random_fe(&a); - random_field_element_magnitude(&a); + random_fe_magnitude(&a); random_fe(&b); - random_field_element_magnitude(&b); + random_fe_magnitude(&b); random_fe_test(&c); - random_field_element_magnitude(&c); + random_fe_magnitude(&c); random_fe_test(&d); - random_field_element_magnitude(&d); + random_fe_magnitude(&d); test_fe_mul(&a, &a, 1); test_fe_mul(&c, &c, 1); test_fe_mul(&a, &b, 0); @@ -3759,17 +3783,17 @@ static void test_ge(void) { secp256k1_gej_set_ge(&gej[3 + 4 * i], &ge[3 + 4 * i]); random_group_element_jacobian_test(&gej[4 + 4 * i], &ge[4 + 4 * i]); for (j = 0; j < 4; j++) { - random_field_element_magnitude(&ge[1 + j + 4 * i].x); - random_field_element_magnitude(&ge[1 + j + 4 * i].y); - random_field_element_magnitude(&gej[1 + j + 4 * i].x); - random_field_element_magnitude(&gej[1 + j + 4 * i].y); - random_field_element_magnitude(&gej[1 + j + 4 * i].z); + random_ge_x_magnitude(&ge[1 + j + 4 * i]); + random_ge_y_magnitude(&ge[1 + j + 4 * i]); + random_gej_x_magnitude(&gej[1 + j + 4 * i]); + random_gej_y_magnitude(&gej[1 + j + 4 * i]); + random_gej_z_magnitude(&gej[1 + j + 4 * i]); } } /* Generate random zf, and zfi2 = 1/zf^2, zfi3 = 1/zf^3 */ random_fe_non_zero_test(&zf); - random_field_element_magnitude(&zf); + random_fe_magnitude(&zf); secp256k1_fe_inv_var(&zfi3, &zf); secp256k1_fe_sqr(&zfi2, &zfi3); secp256k1_fe_mul(&zfi3, &zfi3, &zfi2); @@ -3805,8 +3829,8 @@ static void test_ge(void) { secp256k1_ge ge2_zfi = ge[i2]; /* the second term with x and y rescaled for z = 1/zf */ secp256k1_fe_mul(&ge2_zfi.x, &ge2_zfi.x, &zfi2); secp256k1_fe_mul(&ge2_zfi.y, &ge2_zfi.y, &zfi3); - random_field_element_magnitude(&ge2_zfi.x); - random_field_element_magnitude(&ge2_zfi.y); + random_ge_x_magnitude(&ge2_zfi); + random_ge_y_magnitude(&ge2_zfi); secp256k1_gej_add_zinv_var(&resj, &gej[i1], &ge2_zfi, &zf); ge_equals_gej(&ref, &resj); }