From 20728adc8f5f45c8c15e181e417f5ae7ebab9ee0 Mon Sep 17 00:00:00 2001 From: Andy Polyakov Date: Wed, 21 Jan 2015 17:28:45 +0100 Subject: [PATCH] ec/ecp_nistz256.c: further harmonization with latest rules. Reviewed-by: Tim Hudson --- crypto/ec/ecp_nistz256.c | 122 ++++++++++++++++++++++++--------------- 1 file changed, 74 insertions(+), 48 deletions(-) diff --git a/crypto/ec/ecp_nistz256.c b/crypto/ec/ecp_nistz256.c index 4be34e32af..54a36c7c10 100644 --- a/crypto/ec/ecp_nistz256.c +++ b/crypto/ec/ecp_nistz256.c @@ -71,9 +71,11 @@ typedef P256_POINT_AFFINE PRECOMP256_ROW[64]; typedef struct ec_pre_comp_st { const EC_GROUP *group; /* Parent EC_GROUP object */ size_t w; /* Window size */ - /* Constant time access to the X and Y coordinates of the pre-computed, + /* + * Constant time access to the X and Y coordinates of the pre-computed, * generator multiplies, in the Montgomery domain. Pre-calculated - * multiplies are stored in affine form. */ + * multiplies are stored in affine form. + */ PRECOMP256_ROW *precomp; void *precomp_storage; int references; @@ -89,15 +91,15 @@ void ecp_nistz256_div_by_2(BN_ULONG res[P256_LIMBS], /* Modular mul by 3: res = 3*a mod P */ void ecp_nistz256_mul_by_3(BN_ULONG res[P256_LIMBS], const BN_ULONG a[P256_LIMBS]); -/* Modular add: res = a+b mod P */ +/* Modular add: res = a+b mod P */ void ecp_nistz256_add(BN_ULONG res[P256_LIMBS], const BN_ULONG a[P256_LIMBS], const BN_ULONG b[P256_LIMBS]); -/* Modular sub: res = a-b mod P */ +/* Modular sub: res = a-b mod P */ void ecp_nistz256_sub(BN_ULONG res[P256_LIMBS], const BN_ULONG a[P256_LIMBS], const BN_ULONG b[P256_LIMBS]); -/* Modular neg: res = -a mod P */ +/* Modular neg: res = -a mod P */ void ecp_nistz256_neg(BN_ULONG res[P256_LIMBS], const BN_ULONG a[P256_LIMBS]); /* Montgomery mul: res = a*b*2^-256 mod P */ void ecp_nistz256_mul_mont(BN_ULONG res[P256_LIMBS], @@ -114,11 +116,11 @@ void ecp_nistz256_to_mont(BN_ULONG res[P256_LIMBS], const BN_ULONG in[P256_LIMBS]); /* Functions that perform constant time access to the precomputed tables */ void ecp_nistz256_scatter_w5(P256_POINT *val, - const P256_POINT *in_t, int index); -void ecp_nistz256_gather_w5(P256_POINT * val, + const P256_POINT *in_t, int index); +void ecp_nistz256_gather_w5(P256_POINT *val, const P256_POINT *in_t, int index); void ecp_nistz256_scatter_w7(P256_POINT_AFFINE *val, - const P256_POINT_AFFINE *in_t, int index); + const P256_POINT_AFFINE *in_t, int index); void ecp_nistz256_gather_w7(P256_POINT_AFFINE *val, const P256_POINT_AFFINE *in_t, int index); @@ -279,8 +281,8 @@ static void ecp_nistz256_point_double(P256_POINT *r, const P256_POINT *a) } /* Point addition: r = a+b */ -static void ecp_nistz256_point_add(P256_POINT * r, - const P256_POINT * a, const P256_POINT * b) +static void ecp_nistz256_point_add(P256_POINT *r, + const P256_POINT *a, const P256_POINT *b) { BN_ULONG U2[P256_LIMBS], S2[P256_LIMBS]; BN_ULONG U1[P256_LIMBS], S1[P256_LIMBS]; @@ -336,8 +338,9 @@ static void ecp_nistz256_point_add(P256_POINT * r, ecp_nistz256_mul_mont(U2, in2_x, Z1sqr); /* U2 = X2*Z1^2 */ ecp_nistz256_sub(H, U2, U1); /* H = U2 - U1 */ - /* This should not happen during sign/ecdh, - * so no constant time violation */ + /* + * This should not happen during sign/ecdh, so no constant time violation + */ if (is_equal(U1, U2) && !in1infty && !in2infty) { if (is_equal(S1, S2)) { ecp_nistz256_point_double(r, a); @@ -404,8 +407,10 @@ static void ecp_nistz256_point_add_affine(P256_POINT *r, const BN_ULONG *in2_x = b->X; const BN_ULONG *in2_y = b->Y; - /* In affine representation we encode infty as (0,0), - * which is not on the curve, so it is OK */ + /* + * In affine representation we encode infty as (0,0), which is not on the + * curve, so it is OK + */ in1infty = (in1_x[0] | in1_x[1] | in1_x[2] | in1_x[3] | in1_y[0] | in1_y[1] | in1_y[2] | in1_y[3]); if (P256_LIMBS == 8) @@ -467,8 +472,10 @@ static void ecp_nistz256_point_add_affine(P256_POINT *r, static void ecp_nistz256_mod_inverse(BN_ULONG r[P256_LIMBS], const BN_ULONG in[P256_LIMBS]) { - /* The poly is ffffffff 00000001 00000000 00000000 00000000 ffffffff ffffffff ffffffff - We use FLT and used poly-2 as exponent */ + /* + * The poly is ffffffff 00000001 00000000 00000000 00000000 ffffffff + * ffffffff ffffffff We use FLT and used poly-2 as exponent + */ BN_ULONG p2[P256_LIMBS]; BN_ULONG p4[P256_LIMBS]; BN_ULONG p8[P256_LIMBS]; @@ -538,10 +545,12 @@ static void ecp_nistz256_mod_inverse(BN_ULONG r[P256_LIMBS], memcpy(r, res, sizeof(res)); } -/* ecp_nistz256_bignum_to_field_elem copies the contents of |in| to |out| and - * returns one if it fits. Otherwise it returns zero. */ +/* + * ecp_nistz256_bignum_to_field_elem copies the contents of |in| to |out| and + * returns one if it fits. Otherwise it returns zero. + */ static int ecp_nistz256_bignum_to_field_elem(BN_ULONG out[P256_LIMBS], - const BIGNUM * in) + const BIGNUM *in) { return bn_copy_words(out, in, P256_LIMBS); } @@ -559,9 +568,9 @@ static void ecp_nistz256_windowed_mul(const EC_GROUP *group, const unsigned int window_size = 5; const unsigned int mask = (1 << (window_size + 1)) - 1; unsigned int wvalue; - P256_POINT *temp; /* place for 5 temporary points */ + P256_POINT *temp; /* place for 5 temporary points */ const BIGNUM **scalars = NULL; - P256_POINT(*table)[16] = NULL; + P256_POINT (*table)[16] = NULL; void *table_storage = NULL; if ((table_storage = @@ -574,7 +583,7 @@ static void ecp_nistz256_windowed_mul(const EC_GROUP *group, } table = (void *)ALIGNPTR(table_storage, 64); - temp = (P256_POINT *)(table + num); + temp = (P256_POINT *)(table + num); for (i = 0; i < num; i++) { P256_POINT *row = table[i]; @@ -618,9 +627,10 @@ static void ecp_nistz256_windowed_mul(const EC_GROUP *group, goto err; } - /* row[0] is implicitly (0,0,0) (the point at infinity), - * therefore it is not stored. All other values are actually - * stored with an offset of -1 in table. + /* + * row[0] is implicitly (0,0,0) (the point at infinity), therefore it + * is not stored. All other values are actually stored with an offset + * of -1 in table. */ ecp_nistz256_scatter_w5 (row, &temp[0], 1); @@ -729,8 +739,10 @@ const static BN_ULONG def_yG[P256_LIMBS] = { TOBN(0xd2e88688, 0xdd21f325), TOBN(0x8571ff18, 0x25885d85) }; -/* ecp_nistz256_is_affine_G returns one if |generator| is the standard, - * P-256 generator. */ +/* + * ecp_nistz256_is_affine_G returns one if |generator| is the standard, P-256 + * generator. + */ static int ecp_nistz256_is_affine_G(const EC_POINT *generator) { return (bn_get_top(generator->X) == P256_LIMBS) && @@ -743,10 +755,12 @@ static int ecp_nistz256_is_affine_G(const EC_POINT *generator) static int ecp_nistz256_mult_precompute(EC_GROUP *group, BN_CTX *ctx) { - /* We precompute a table for a Booth encoded exponent (wNAF) based + /* + * We precompute a table for a Booth encoded exponent (wNAF) based * computation. Each table holds 64 values for safe access, with an - * implicit value of infinity at index zero. We use window of size 7, - * and therefore require ceil(256/7) = 37 tables. */ + * implicit value of infinity at index zero. We use window of size 7, and + * therefore require ceil(256/7) = 37 tables. + */ BIGNUM *order; EC_POINT *P = NULL, *T = NULL; const EC_POINT *generator; @@ -769,8 +783,10 @@ static int ecp_nistz256_mult_precompute(EC_GROUP *group, BN_CTX *ctx) } if (ecp_nistz256_is_affine_G(generator)) { - /* No need to calculate tables for the standard generator - * because we have them statically. */ + /* + * No need to calculate tables for the standard generator because we + * have them statically. + */ return 1; } @@ -810,17 +826,20 @@ static int ecp_nistz256_mult_precompute(EC_GROUP *group, BN_CTX *ctx) P = EC_POINT_new(group); T = EC_POINT_new(group); - /* The zero entry is implicitly infinity, and we skip it, - * storing other values with -1 offset. */ + /* + * The zero entry is implicitly infinity, and we skip it, storing other + * values with -1 offset. + */ EC_POINT_copy(T, generator); for (k = 0; k < 64; k++) { EC_POINT_copy(P, T); for (j = 0; j < 37; j++) { P256_POINT_AFFINE temp; - /* It would be faster to use - * ec_GFp_simple_points_make_affine and make multiple - * points affine at the same time. */ + /* + * It would be faster to use ec_GFp_simple_points_make_affine and + * make multiple points affine at the same time. + */ ec_GFp_simple_make_affine(group, P, ctx); ecp_nistz256_bignum_to_field_elem(temp.X, P->X); ecp_nistz256_bignum_to_field_elem(temp.Y, P->Y); @@ -907,9 +926,11 @@ static void booth_recode_w7(unsigned char *sign, *digit = d; } -/* ecp_nistz256_avx2_mul_g performs multiplication by G, using only the +/* + * ecp_nistz256_avx2_mul_g performs multiplication by G, using only the * precomputed table. It does 4 affine point additions in parallel, - * significantly speeding up point multiplication for a fixed value. */ + * significantly speeding up point multiplication for a fixed value. + */ static void ecp_nistz256_avx2_mul_g(P256_POINT *r, unsigned char p_str[33], const P256_POINT_AFFINE(*preComputedTable)[64]) @@ -1159,9 +1180,10 @@ static int ecp_nistz256_points_mul(const EC_GROUP *group, ecp_nistz256_pre_comp_clear_free); if (pre_comp) { - /* If there is a precomputed table for the generator, - * check that it was generated with the same - * generator. */ + /* + * If there is a precomputed table for the generator, check that + * it was generated with the same generator. + */ EC_POINT *pre_comp_generator = EC_POINT_new(group); if (pre_comp_generator == NULL) goto err; @@ -1178,10 +1200,12 @@ static int ecp_nistz256_points_mul(const EC_GROUP *group, } if (preComputedTable == NULL && ecp_nistz256_is_affine_G(generator)) { - /* If there is no precomputed data, but the generator - * is the default, a hardcoded table of precomputed - * data is used. This is because applications, such as - * Apache, do not use EC_KEY_precompute_mult. */ + /* + * If there is no precomputed data, but the generator is the + * default, a hardcoded table of precomputed data is used. This + * is because applications, such as Apache, do not use + * EC_KEY_precompute_mult. + */ preComputedTable = ecp_nistz256_precomputed; } @@ -1262,8 +1286,10 @@ static int ecp_nistz256_points_mul(const EC_GROUP *group, p_is_infinity = 1; if (no_precomp_for_generator) { - /* Without a precomputed table for the generator, it has to be - * handled like a normal point. */ + /* + * Without a precomputed table for the generator, it has to be + * handled like a normal point. + */ const BIGNUM **new_scalars; const EC_POINT **new_points; -- 2.25.1