diff options
Diffstat (limited to 'crypto/openssl/crypto/ec/ecp_nistz256.c')
| -rw-r--r-- | crypto/openssl/crypto/ec/ecp_nistz256.c | 125 |
1 files changed, 86 insertions, 39 deletions
diff --git a/crypto/openssl/crypto/ec/ecp_nistz256.c b/crypto/openssl/crypto/ec/ecp_nistz256.c index ca44d0a..99b8d61 100644 --- a/crypto/openssl/crypto/ec/ecp_nistz256.c +++ b/crypto/openssl/crypto/ec/ecp_nistz256.c @@ -82,19 +82,36 @@ typedef struct ec_pre_comp_st { } EC_PRE_COMP; /* Functions implemented in assembly */ +/* + * Most of below mentioned functions *preserve* the property of inputs + * being fully reduced, i.e. being in [0, modulus) range. Simply put if + * inputs are fully reduced, then output is too. Note that reverse is + * not true, in sense that given partially reduced inputs output can be + * either, not unlikely reduced. And "most" in first sentence refers to + * the fact that given the calculations flow one can tolerate that + * addition, 1st function below, produces partially reduced result *if* + * multiplications by 2 and 3, which customarily use addition, fully + * reduce it. This effectively gives two options: a) addition produces + * fully reduced result [as long as inputs are, just like remaining + * functions]; b) addition is allowed to produce partially reduced + * result, but multiplications by 2 and 3 perform additional reduction + * step. Choice between the two can be platform-specific, but it was a) + * in all cases so far... + */ +/* 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 mul by 2: res = 2*a mod P */ void ecp_nistz256_mul_by_2(BN_ULONG res[P256_LIMBS], const BN_ULONG a[P256_LIMBS]); -/* Modular div by 2: res = a/2 mod P */ -void ecp_nistz256_div_by_2(BN_ULONG res[P256_LIMBS], - const BN_ULONG a[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 */ -void ecp_nistz256_add(BN_ULONG res[P256_LIMBS], - const BN_ULONG a[P256_LIMBS], - const BN_ULONG b[P256_LIMBS]); + +/* Modular div by 2: res = a/2 mod P */ +void ecp_nistz256_div_by_2(BN_ULONG res[P256_LIMBS], + const BN_ULONG a[P256_LIMBS]); /* Modular sub: res = a-b mod P */ void ecp_nistz256_sub(BN_ULONG res[P256_LIMBS], const BN_ULONG a[P256_LIMBS], @@ -205,21 +222,29 @@ static BN_ULONG is_equal(const BN_ULONG a[P256_LIMBS], return is_zero(res); } -static BN_ULONG is_one(const BN_ULONG a[P256_LIMBS]) +static BN_ULONG is_one(const BIGNUM *z) { - BN_ULONG res; - - res = a[0] ^ ONE[0]; - res |= a[1] ^ ONE[1]; - res |= a[2] ^ ONE[2]; - res |= a[3] ^ ONE[3]; - if (P256_LIMBS == 8) { - res |= a[4] ^ ONE[4]; - res |= a[5] ^ ONE[5]; - res |= a[6] ^ ONE[6]; + BN_ULONG res = 0; + BN_ULONG *a = z->d; + + if (z->top == (P256_LIMBS - P256_LIMBS / 8)) { + res = a[0] ^ ONE[0]; + res |= a[1] ^ ONE[1]; + res |= a[2] ^ ONE[2]; + res |= a[3] ^ ONE[3]; + if (P256_LIMBS == 8) { + res |= a[4] ^ ONE[4]; + res |= a[5] ^ ONE[5]; + res |= a[6] ^ ONE[6]; + /* + * no check for a[7] (being zero) on 32-bit platforms, + * because value of "one" takes only 7 limbs. + */ + } + res = is_zero(res); } - return is_zero(res); + return res; } static int ecp_nistz256_set_words(BIGNUM *a, BN_ULONG words[P256_LIMBS]) @@ -315,19 +340,16 @@ static void ecp_nistz256_point_add(P256_POINT *r, const BN_ULONG *in2_y = b->Y; const BN_ULONG *in2_z = b->Z; - /* We encode infinity 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]); + /* + * Infinity in encoded as (,,0) + */ + in1infty = (in1_z[0] | in1_z[1] | in1_z[2] | in1_z[3]); if (P256_LIMBS == 8) - in1infty |= (in1_x[4] | in1_x[5] | in1_x[6] | in1_x[7] | - in1_y[4] | in1_y[5] | in1_y[6] | in1_y[7]); + in1infty |= (in1_z[4] | in1_z[5] | in1_z[6] | in1_z[7]); - in2infty = (in2_x[0] | in2_x[1] | in2_x[2] | in2_x[3] | - in2_y[0] | in2_y[1] | in2_y[2] | in2_y[3]); + in2infty = (in2_z[0] | in2_z[1] | in2_z[2] | in2_z[3]); if (P256_LIMBS == 8) - in2infty |= (in2_x[4] | in2_x[5] | in2_x[6] | in2_x[7] | - in2_y[4] | in2_y[5] | in2_y[6] | in2_y[7]); + in2infty |= (in2_z[4] | in2_z[5] | in2_z[6] | in2_z[7]); in1infty = is_zero(in1infty); in2infty = is_zero(in2infty); @@ -416,15 +438,16 @@ static void ecp_nistz256_point_add_affine(P256_POINT *r, 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 + * Infinity in encoded as (,,0) */ - 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]); + in1infty = (in1_z[0] | in1_z[1] | in1_z[2] | in1_z[3]); if (P256_LIMBS == 8) - in1infty |= (in1_x[4] | in1_x[5] | in1_x[6] | in1_x[7] | - in1_y[4] | in1_y[5] | in1_y[6] | in1_y[7]); + in1infty |= (in1_z[4] | in1_z[5] | in1_z[6] | in1_z[7]); + /* + * In affine representation we encode infinity as (0,0), which is + * not on the curve, so it is OK + */ in2infty = (in2_x[0] | in2_x[1] | in2_x[2] | in2_x[3] | in2_y[0] | in2_y[1] | in2_y[2] | in2_y[3]); if (P256_LIMBS == 8) @@ -741,9 +764,8 @@ static int ecp_nistz256_is_affine_G(const EC_POINT *generator) { return (generator->X.top == P256_LIMBS) && (generator->Y.top == P256_LIMBS) && - (generator->Z.top == (P256_LIMBS - P256_LIMBS / 8)) && is_equal(generator->X.d, def_xG) && - is_equal(generator->Y.d, def_yG) && is_one(generator->Z.d); + is_equal(generator->Y.d, def_yG) && is_one(&generator->Z); } static int ecp_nistz256_mult_precompute(EC_GROUP *group, BN_CTX *ctx) @@ -1249,6 +1271,8 @@ static int ecp_nistz256_points_mul(const EC_GROUP *group, } else #endif { + BN_ULONG infty; + /* First window */ wvalue = (p_str[0] << 1) & mask; index += window_size; @@ -1260,7 +1284,30 @@ static int ecp_nistz256_points_mul(const EC_GROUP *group, ecp_nistz256_neg(p.p.Z, p.p.Y); copy_conditional(p.p.Y, p.p.Z, wvalue & 1); - memcpy(p.p.Z, ONE, sizeof(ONE)); + /* + * Since affine infinity is encoded as (0,0) and + * Jacobian ias (,,0), we need to harmonize them + * by assigning "one" or zero to Z. + */ + infty = (p.p.X[0] | p.p.X[1] | p.p.X[2] | p.p.X[3] | + p.p.Y[0] | p.p.Y[1] | p.p.Y[2] | p.p.Y[3]); + if (P256_LIMBS == 8) + infty |= (p.p.X[4] | p.p.X[5] | p.p.X[6] | p.p.X[7] | + p.p.Y[4] | p.p.Y[5] | p.p.Y[6] | p.p.Y[7]); + + infty = 0 - is_zero(infty); + infty = ~infty; + + p.p.Z[0] = ONE[0] & infty; + p.p.Z[1] = ONE[1] & infty; + p.p.Z[2] = ONE[2] & infty; + p.p.Z[3] = ONE[3] & infty; + if (P256_LIMBS == 8) { + p.p.Z[4] = ONE[4] & infty; + p.p.Z[5] = ONE[5] & infty; + p.p.Z[6] = ONE[6] & infty; + p.p.Z[7] = ONE[7] & infty; + } for (i = 1; i < 37; i++) { unsigned int off = (index - 1) / 8; @@ -1331,7 +1378,7 @@ static int ecp_nistz256_points_mul(const EC_GROUP *group, !ecp_nistz256_set_words(&r->Z, p.p.Z)) { goto err; } - r->Z_is_one = is_one(p.p.Z) & 1; + r->Z_is_one = is_one(&r->Z) & 1; ret = 1; |
