diff options
author | Matt Caswell <matt@openssl.org> | 2017-11-28 14:56:43 +0000 |
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committer | Matt Caswell <matt@openssl.org> | 2018-02-20 12:59:30 +0000 |
commit | bb6e60adc5d02d903cbbf92cf7b1d7152fb4a905 (patch) | |
tree | 89a7c746ef765fabd553582fa9f0967d1d642785 /crypto/ec/curve448/curve448.c | |
parent | c4148792cf643677839096742ee090fe6f4ac910 (diff) |
Rename the decaf files to curve448 files
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/5105)
Diffstat (limited to 'crypto/ec/curve448/curve448.c')
-rw-r--r-- | crypto/ec/curve448/curve448.c | 726 |
1 files changed, 726 insertions, 0 deletions
diff --git a/crypto/ec/curve448/curve448.c b/crypto/ec/curve448/curve448.c new file mode 100644 index 0000000000..d5b684b3bd --- /dev/null +++ b/crypto/ec/curve448/curve448.c @@ -0,0 +1,726 @@ +/** + * @file ed448goldilocks/decaf.c + * @author Mike Hamburg + * + * @copyright + * Copyright (c) 2015-2016 Cryptography Research, Inc. \n + * Released under the MIT License. See LICENSE.txt for license information. + * + * @brief Decaf high-level functions. + * + * @warning This file was automatically generated in Python. + * Please do not edit it. + */ +#include <openssl/crypto.h> +#include "word.h" +#include "field.h" + +#include "point_448.h" +#include "ed448.h" +#include "curve448_lcl.h" + +#define COFACTOR 4 + +/* Comb config: number of combs, n, t, s. */ +#define COMBS_N 5 +#define COMBS_T 5 +#define COMBS_S 18 +#define DECAF_WINDOW_BITS 5 +#define DECAF_WNAF_FIXED_TABLE_BITS 5 +#define DECAF_WNAF_VAR_TABLE_BITS 3 + +static const int EDWARDS_D = -39081; +static const curve448_scalar_t precomputed_scalarmul_adjustment = {{{ + SC_LIMB(0xc873d6d54a7bb0cf), SC_LIMB(0xe933d8d723a70aad), SC_LIMB(0xbb124b65129c96fd), SC_LIMB(0x00000008335dc163) +}}}; + +const uint8_t decaf_x448_base_point[DECAF_X448_PUBLIC_BYTES] = { 0x05 }; + +#define RISTRETTO_FACTOR DECAF_448_RISTRETTO_FACTOR +const gf RISTRETTO_FACTOR = {{{ + 0x42ef0f45572736, 0x7bf6aa20ce5296, 0xf4fd6eded26033, 0x968c14ba839a66, 0xb8d54b64a2d780, 0x6aa0a1f1a7b8a5, 0x683bf68d722fa2, 0x22d962fbeb24f7 +}}}; + + +#define TWISTED_D ((EDWARDS_D)-1) + +#define EFF_D (-(TWISTED_D)) +#define NEG_D 1 + +/* End of template stuff */ + +#define WBITS DECAF_WORD_BITS /* NB this may be different from ARCH_WORD_BITS */ + +/* Projective Niels coordinates */ +typedef struct { gf a, b, c; } niels_s, niels_t[1]; +typedef struct { niels_t n; gf z; } VECTOR_ALIGNED pniels_s, pniels_t[1]; + +/* Precomputed base */ +struct curve448_precomputed_s { niels_t table [COMBS_N<<(COMBS_T-1)]; }; + +extern const gf curve448_precomputed_base_as_fe[]; +const curve448_precomputed_s *curve448_precomputed_base = + (const curve448_precomputed_s *) &curve448_precomputed_base_as_fe; + +/** Inverse. */ +static void +gf_invert(gf y, const gf x, int assert_nonzero) { + gf t1, t2; + gf_sqr(t1, x); // o^2 + mask_t ret = gf_isr(t2, t1); // +-1/sqrt(o^2) = +-1/o + (void)ret; + if (assert_nonzero) assert(ret); + gf_sqr(t1, t2); + gf_mul(t2, t1, x); // not direct to y in case of alias. + gf_copy(y, t2); +} + +/** identity = (0,1) */ +const curve448_point_t curve448_point_identity = {{{{{0}}},{{{1}}},{{{1}}},{{{0}}}}}; + +static void +point_double_internal ( + curve448_point_t p, + const curve448_point_t q, + int before_double +) { + gf a, b, c, d; + gf_sqr ( c, q->x ); + gf_sqr ( a, q->y ); + gf_add_nr ( d, c, a ); /* 2+e */ + gf_add_nr ( p->t, q->y, q->x ); /* 2+e */ + gf_sqr ( b, p->t ); + gf_subx_nr ( b, b, d, 3 ); /* 4+e */ + gf_sub_nr ( p->t, a, c ); /* 3+e */ + gf_sqr ( p->x, q->z ); + gf_add_nr ( p->z, p->x, p->x ); /* 2+e */ + gf_subx_nr ( a, p->z, p->t, 4 ); /* 6+e */ + if (GF_HEADROOM == 5) gf_weak_reduce(a); /* or 1+e */ + gf_mul ( p->x, a, b ); + gf_mul ( p->z, p->t, a ); + gf_mul ( p->y, p->t, d ); + if (!before_double) gf_mul ( p->t, b, d ); +} + +void curve448_point_double(curve448_point_t p, const curve448_point_t q) { + point_double_internal(p,q,0); +} + +/* Operations on [p]niels */ +static ossl_inline void +cond_neg_niels ( + niels_t n, + mask_t neg +) { + gf_cond_swap(n->a, n->b, neg); + gf_cond_neg(n->c, neg); +} + +static void pt_to_pniels ( + pniels_t b, + const curve448_point_t a +) { + gf_sub ( b->n->a, a->y, a->x ); + gf_add ( b->n->b, a->x, a->y ); + gf_mulw ( b->n->c, a->t, 2*TWISTED_D ); + gf_add ( b->z, a->z, a->z ); +} + +static void pniels_to_pt ( + curve448_point_t e, + const pniels_t d +) { + gf eu; + gf_add ( eu, d->n->b, d->n->a ); + gf_sub ( e->y, d->n->b, d->n->a ); + gf_mul ( e->t, e->y, eu); + gf_mul ( e->x, d->z, e->y ); + gf_mul ( e->y, d->z, eu ); + gf_sqr ( e->z, d->z ); +} + +static void +niels_to_pt ( + curve448_point_t e, + const niels_t n +) { + gf_add ( e->y, n->b, n->a ); + gf_sub ( e->x, n->b, n->a ); + gf_mul ( e->t, e->y, e->x ); + gf_copy ( e->z, ONE ); +} + +static void +add_niels_to_pt ( + curve448_point_t d, + const niels_t e, + int before_double +) { + gf a, b, c; + gf_sub_nr ( b, d->y, d->x ); /* 3+e */ + gf_mul ( a, e->a, b ); + gf_add_nr ( b, d->x, d->y ); /* 2+e */ + gf_mul ( d->y, e->b, b ); + gf_mul ( d->x, e->c, d->t ); + gf_add_nr ( c, a, d->y ); /* 2+e */ + gf_sub_nr ( b, d->y, a ); /* 3+e */ + gf_sub_nr ( d->y, d->z, d->x ); /* 3+e */ + gf_add_nr ( a, d->x, d->z ); /* 2+e */ + gf_mul ( d->z, a, d->y ); + gf_mul ( d->x, d->y, b ); + gf_mul ( d->y, a, c ); + if (!before_double) gf_mul ( d->t, b, c ); +} + +static void +sub_niels_from_pt ( + curve448_point_t d, + const niels_t e, + int before_double +) { + gf a, b, c; + gf_sub_nr ( b, d->y, d->x ); /* 3+e */ + gf_mul ( a, e->b, b ); + gf_add_nr ( b, d->x, d->y ); /* 2+e */ + gf_mul ( d->y, e->a, b ); + gf_mul ( d->x, e->c, d->t ); + gf_add_nr ( c, a, d->y ); /* 2+e */ + gf_sub_nr ( b, d->y, a ); /* 3+e */ + gf_add_nr ( d->y, d->z, d->x ); /* 2+e */ + gf_sub_nr ( a, d->z, d->x ); /* 3+e */ + gf_mul ( d->z, a, d->y ); + gf_mul ( d->x, d->y, b ); + gf_mul ( d->y, a, c ); + if (!before_double) gf_mul ( d->t, b, c ); +} + +static void +add_pniels_to_pt ( + curve448_point_t p, + const pniels_t pn, + int before_double +) { + gf L0; + gf_mul ( L0, p->z, pn->z ); + gf_copy ( p->z, L0 ); + add_niels_to_pt( p, pn->n, before_double ); +} + +static void +sub_pniels_from_pt ( + curve448_point_t p, + const pniels_t pn, + int before_double +) { + gf L0; + gf_mul ( L0, p->z, pn->z ); + gf_copy ( p->z, L0 ); + sub_niels_from_pt( p, pn->n, before_double ); +} + +decaf_bool_t curve448_point_eq ( const curve448_point_t p, const curve448_point_t q ) { + /* equality mod 2-torsion compares x/y */ + gf a, b; + gf_mul ( a, p->y, q->x ); + gf_mul ( b, q->y, p->x ); + mask_t succ = gf_eq(a,b); + + return mask_to_bool(succ); +} + +decaf_bool_t curve448_point_valid ( + const curve448_point_t p +) { + gf a,b,c; + gf_mul(a,p->x,p->y); + gf_mul(b,p->z,p->t); + mask_t out = gf_eq(a,b); + gf_sqr(a,p->x); + gf_sqr(b,p->y); + gf_sub(a,b,a); + gf_sqr(b,p->t); + gf_mulw(c,b,TWISTED_D); + gf_sqr(b,p->z); + gf_add(b,b,c); + out &= gf_eq(a,b); + out &= ~gf_eq(p->z,ZERO); + return mask_to_bool(out); +} + +static ossl_inline void +constant_time_lookup_niels ( + niels_s *__restrict__ ni, + const niels_t *table, + int nelts, + int idx +) { + constant_time_lookup(ni, table, sizeof(niels_s), nelts, idx); +} + +void curve448_precomputed_scalarmul ( + curve448_point_t out, + const curve448_precomputed_s *table, + const curve448_scalar_t scalar +) { + int i; + unsigned j,k; + const unsigned int n = COMBS_N, t = COMBS_T, s = COMBS_S; + + curve448_scalar_t scalar1x; + curve448_scalar_add(scalar1x, scalar, precomputed_scalarmul_adjustment); + curve448_scalar_halve(scalar1x,scalar1x); + + niels_t ni; + + for (i=s-1; i>=0; i--) { + if (i != (int)s-1) point_double_internal(out,out,0); + + for (j=0; j<n; j++) { + int tab = 0; + + for (k=0; k<t; k++) { + unsigned int bit = i + s*(k + j*t); + if (bit < DECAF_448_SCALAR_BITS) { + tab |= (scalar1x->limb[bit/WBITS] >> (bit%WBITS) & 1) << k; + } + } + + mask_t invert = (tab>>(t-1))-1; + tab ^= invert; + tab &= (1<<(t-1)) - 1; + + constant_time_lookup_niels(ni, &table->table[j<<(t-1)], 1<<(t-1), tab); + + cond_neg_niels(ni, invert); + if ((i!=(int)s-1)||j) { + add_niels_to_pt(out, ni, j==n-1 && i); + } else { + niels_to_pt(out, ni); + } + } + } + + OPENSSL_cleanse(ni,sizeof(ni)); + OPENSSL_cleanse(scalar1x,sizeof(scalar1x)); +} + +void curve448_point_mul_by_ratio_and_encode_like_eddsa ( + uint8_t enc[DECAF_EDDSA_448_PUBLIC_BYTES], + const curve448_point_t p +) { + + /* The point is now on the twisted curve. Move it to untwisted. */ + gf x, y, z, t; + curve448_point_t q; + curve448_point_copy(q,p); + + { + /* 4-isogeny: 2xy/(y^+x^2), (y^2-x^2)/(2z^2-y^2+x^2) */ + gf u; + gf_sqr ( x, q->x ); + gf_sqr ( t, q->y ); + gf_add( u, x, t ); + gf_add( z, q->y, q->x ); + gf_sqr ( y, z); + gf_sub ( y, y, u ); + gf_sub ( z, t, x ); + gf_sqr ( x, q->z ); + gf_add ( t, x, x); + gf_sub ( t, t, z); + gf_mul ( x, t, y ); + gf_mul ( y, z, u ); + gf_mul ( z, u, t ); + OPENSSL_cleanse(u,sizeof(u)); + } + + /* Affinize */ + gf_invert(z,z,1); + gf_mul(t,x,z); + gf_mul(x,y,z); + + /* Encode */ + enc[DECAF_EDDSA_448_PRIVATE_BYTES-1] = 0; + gf_serialize(enc, x, 1); + enc[DECAF_EDDSA_448_PRIVATE_BYTES-1] |= 0x80 & gf_lobit(t); + + OPENSSL_cleanse(x,sizeof(x)); + OPENSSL_cleanse(y,sizeof(y)); + OPENSSL_cleanse(z,sizeof(z)); + OPENSSL_cleanse(t,sizeof(t)); + curve448_point_destroy(q); +} + + +decaf_error_t curve448_point_decode_like_eddsa_and_mul_by_ratio ( + curve448_point_t p, + const uint8_t enc[DECAF_EDDSA_448_PUBLIC_BYTES] +) { + uint8_t enc2[DECAF_EDDSA_448_PUBLIC_BYTES]; + memcpy(enc2,enc,sizeof(enc2)); + + mask_t low = ~word_is_zero(enc2[DECAF_EDDSA_448_PRIVATE_BYTES-1] & 0x80); + enc2[DECAF_EDDSA_448_PRIVATE_BYTES-1] &= ~0x80; + + mask_t succ = gf_deserialize(p->y, enc2, 1, 0); +#if 0 == 0 + succ &= word_is_zero(enc2[DECAF_EDDSA_448_PRIVATE_BYTES-1]); +#endif + + gf_sqr(p->x,p->y); + gf_sub(p->z,ONE,p->x); /* num = 1-y^2 */ + gf_mulw(p->t,p->x,EDWARDS_D); /* dy^2 */ + gf_sub(p->t,ONE,p->t); /* denom = 1-dy^2 or 1-d + dy^2 */ + + gf_mul(p->x,p->z,p->t); + succ &= gf_isr(p->t,p->x); /* 1/sqrt(num * denom) */ + + gf_mul(p->x,p->t,p->z); /* sqrt(num / denom) */ + gf_cond_neg(p->x,gf_lobit(p->x)^low); + gf_copy(p->z,ONE); + + { + /* 4-isogeny 2xy/(y^2-ax^2), (y^2+ax^2)/(2-y^2-ax^2) */ + gf a, b, c, d; + gf_sqr ( c, p->x ); + gf_sqr ( a, p->y ); + gf_add ( d, c, a ); + gf_add ( p->t, p->y, p->x ); + gf_sqr ( b, p->t ); + gf_sub ( b, b, d ); + gf_sub ( p->t, a, c ); + gf_sqr ( p->x, p->z ); + gf_add ( p->z, p->x, p->x ); + gf_sub ( a, p->z, d ); + gf_mul ( p->x, a, b ); + gf_mul ( p->z, p->t, a ); + gf_mul ( p->y, p->t, d ); + gf_mul ( p->t, b, d ); + OPENSSL_cleanse(a,sizeof(a)); + OPENSSL_cleanse(b,sizeof(b)); + OPENSSL_cleanse(c,sizeof(c)); + OPENSSL_cleanse(d,sizeof(d)); + } + + OPENSSL_cleanse(enc2,sizeof(enc2)); + assert(curve448_point_valid(p) || ~succ); + + return decaf_succeed_if(mask_to_bool(succ)); +} + +decaf_error_t decaf_x448 ( + uint8_t out[X_PUBLIC_BYTES], + const uint8_t base[X_PUBLIC_BYTES], + const uint8_t scalar[X_PRIVATE_BYTES] +) { + gf x1, x2, z2, x3, z3, t1, t2; + ignore_result(gf_deserialize(x1,base,1,0)); + gf_copy(x2,ONE); + gf_copy(z2,ZERO); + gf_copy(x3,x1); + gf_copy(z3,ONE); + + int t; + mask_t swap = 0; + + for (t = X_PRIVATE_BITS-1; t>=0; t--) { + uint8_t sb = scalar[t/8]; + + /* Scalar conditioning */ + if (t/8==0) sb &= -(uint8_t)COFACTOR; + else if (t == X_PRIVATE_BITS-1) sb = -1; + + mask_t k_t = (sb>>(t%8)) & 1; + k_t = -k_t; /* set to all 0s or all 1s */ + + swap ^= k_t; + gf_cond_swap(x2,x3,swap); + gf_cond_swap(z2,z3,swap); + swap = k_t; + + gf_add_nr(t1,x2,z2); /* A = x2 + z2 */ /* 2+e */ + gf_sub_nr(t2,x2,z2); /* B = x2 - z2 */ /* 3+e */ + gf_sub_nr(z2,x3,z3); /* D = x3 - z3 */ /* 3+e */ + gf_mul(x2,t1,z2); /* DA */ + gf_add_nr(z2,z3,x3); /* C = x3 + z3 */ /* 2+e */ + gf_mul(x3,t2,z2); /* CB */ + gf_sub_nr(z3,x2,x3); /* DA-CB */ /* 3+e */ + gf_sqr(z2,z3); /* (DA-CB)^2 */ + gf_mul(z3,x1,z2); /* z3 = x1(DA-CB)^2 */ + gf_add_nr(z2,x2,x3); /* (DA+CB) */ /* 2+e */ + gf_sqr(x3,z2); /* x3 = (DA+CB)^2 */ + + gf_sqr(z2,t1); /* AA = A^2 */ + gf_sqr(t1,t2); /* BB = B^2 */ + gf_mul(x2,z2,t1); /* x2 = AA*BB */ + gf_sub_nr(t2,z2,t1); /* E = AA-BB */ /* 3+e */ + + gf_mulw(t1,t2,-EDWARDS_D); /* E*-d = a24*E */ + gf_add_nr(t1,t1,z2); /* AA + a24*E */ /* 2+e */ + gf_mul(z2,t2,t1); /* z2 = E(AA+a24*E) */ + } + + /* Finish */ + gf_cond_swap(x2,x3,swap); + gf_cond_swap(z2,z3,swap); + gf_invert(z2,z2,0); + gf_mul(x1,x2,z2); + gf_serialize(out,x1,1); + mask_t nz = ~gf_eq(x1,ZERO); + + OPENSSL_cleanse(x1,sizeof(x1)); + OPENSSL_cleanse(x2,sizeof(x2)); + OPENSSL_cleanse(z2,sizeof(z2)); + OPENSSL_cleanse(x3,sizeof(x3)); + OPENSSL_cleanse(z3,sizeof(z3)); + OPENSSL_cleanse(t1,sizeof(t1)); + OPENSSL_cleanse(t2,sizeof(t2)); + + return decaf_succeed_if(mask_to_bool(nz)); +} + +/* Thanks Johan Pascal */ +void decaf_ed448_convert_public_key_to_x448 ( + uint8_t x[DECAF_X448_PUBLIC_BYTES], + const uint8_t ed[DECAF_EDDSA_448_PUBLIC_BYTES] +) { + gf y; + const uint8_t mask = (uint8_t)(0xFE<<(7)); + ignore_result(gf_deserialize(y, ed, 1, mask)); + + { + gf n,d; + + /* u = y^2 * (1-dy^2) / (1-y^2) */ + gf_sqr(n,y); /* y^2*/ + gf_sub(d,ONE,n); /* 1-y^2*/ + gf_invert(d,d,0); /* 1/(1-y^2)*/ + gf_mul(y,n,d); /* y^2 / (1-y^2) */ + gf_mulw(d,n,EDWARDS_D); /* dy^2*/ + gf_sub(d, ONE, d); /* 1-dy^2*/ + gf_mul(n, y, d); /* y^2 * (1-dy^2) / (1-y^2) */ + gf_serialize(x,n,1); + + OPENSSL_cleanse(y,sizeof(y)); + OPENSSL_cleanse(n,sizeof(n)); + OPENSSL_cleanse(d,sizeof(d)); + } +} + +void curve448_point_mul_by_ratio_and_encode_like_x448 ( + uint8_t out[X_PUBLIC_BYTES], + const curve448_point_t p +) { + curve448_point_t q; + curve448_point_copy(q,p); + gf_invert(q->t,q->x,0); /* 1/x */ + gf_mul(q->z,q->t,q->y); /* y/x */ + gf_sqr(q->y,q->z); /* (y/x)^2 */ + gf_serialize(out,q->y,1); + curve448_point_destroy(q); +} + +void decaf_x448_derive_public_key ( + uint8_t out[X_PUBLIC_BYTES], + const uint8_t scalar[X_PRIVATE_BYTES] +) { + /* Scalar conditioning */ + uint8_t scalar2[X_PRIVATE_BYTES]; + memcpy(scalar2,scalar,sizeof(scalar2)); + scalar2[0] &= -(uint8_t)COFACTOR; + + scalar2[X_PRIVATE_BYTES-1] &= ~(-1u<<((X_PRIVATE_BITS+7)%8)); + scalar2[X_PRIVATE_BYTES-1] |= 1<<((X_PRIVATE_BITS+7)%8); + + curve448_scalar_t the_scalar; + curve448_scalar_decode_long(the_scalar,scalar2,sizeof(scalar2)); + + /* Compensate for the encoding ratio */ + for (unsigned i=1; i<DECAF_X448_ENCODE_RATIO; i<<=1) { + curve448_scalar_halve(the_scalar,the_scalar); + } + curve448_point_t p; + curve448_precomputed_scalarmul(p,curve448_precomputed_base,the_scalar); + curve448_point_mul_by_ratio_and_encode_like_x448(out,p); + curve448_point_destroy(p); +} + +/** + * @cond internal + * Control for variable-time scalar multiply algorithms. + */ +struct smvt_control { + int power, addend; +}; + +static int recode_wnaf ( + struct smvt_control *control, /* [nbits/(table_bits+1) + 3] */ + const curve448_scalar_t scalar, + unsigned int table_bits +) { + unsigned int table_size = DECAF_448_SCALAR_BITS/(table_bits+1) + 3; + int position = table_size - 1; /* at the end */ + + /* place the end marker */ + control[position].power = -1; + control[position].addend = 0; + position--; + + /* PERF: Could negate scalar if it's large. But then would need more cases + * in the actual code that uses it, all for an expected reduction of like 1/5 op. + * Probably not worth it. + */ + + uint64_t current = scalar->limb[0] & 0xFFFF; + uint32_t mask = (1<<(table_bits+1))-1; + + unsigned int w; + const unsigned int B_OVER_16 = sizeof(scalar->limb[0]) / 2; + for (w = 1; w<(DECAF_448_SCALAR_BITS-1)/16+3; w++) { + if (w < (DECAF_448_SCALAR_BITS-1)/16+1) { + /* Refill the 16 high bits of current */ + current += (uint32_t)((scalar->limb[w/B_OVER_16]>>(16*(w%B_OVER_16)))<<16); + } + + while (current & 0xFFFF) { + assert(position >= 0); + uint32_t pos = __builtin_ctz((uint32_t)current), odd = (uint32_t)current >> pos; + int32_t delta = odd & mask; + if (odd & 1<<(table_bits+1)) delta -= (1<<(table_bits+1)); + current -= delta << pos; + control[position].power = pos + 16*(w-1); + control[position].addend = delta; + position--; + } + current >>= 16; + } + assert(current==0); + + position++; + unsigned int n = table_size - position; + unsigned int i; + for (i=0; i<n; i++) { + control[i] = control[i+position]; + } + return n-1; +} + +static void +prepare_wnaf_table( + pniels_t *output, + const curve448_point_t working, + unsigned int tbits +) { + curve448_point_t tmp; + int i; + pt_to_pniels(output[0], working); + + if (tbits == 0) return; + + curve448_point_double(tmp,working); + pniels_t twop; + pt_to_pniels(twop, tmp); + + add_pniels_to_pt(tmp, output[0],0); + pt_to_pniels(output[1], tmp); + + for (i=2; i < 1<<tbits; i++) { + add_pniels_to_pt(tmp, twop,0); + pt_to_pniels(output[i], tmp); + } + + curve448_point_destroy(tmp); + OPENSSL_cleanse(twop,sizeof(twop)); +} + +extern const gf curve448_precomputed_wnaf_as_fe[]; +static const niels_t *curve448_wnaf_base = (const niels_t *)curve448_precomputed_wnaf_as_fe; + +void curve448_base_double_scalarmul_non_secret ( + curve448_point_t combo, + const curve448_scalar_t scalar1, + const curve448_point_t base2, + const curve448_scalar_t scalar2 +) { + const int table_bits_var = DECAF_WNAF_VAR_TABLE_BITS, + table_bits_pre = DECAF_WNAF_FIXED_TABLE_BITS; + struct smvt_control control_var[DECAF_448_SCALAR_BITS/(table_bits_var+1)+3]; + struct smvt_control control_pre[DECAF_448_SCALAR_BITS/(table_bits_pre+1)+3]; + + int ncb_pre = recode_wnaf(control_pre, scalar1, table_bits_pre); + int ncb_var = recode_wnaf(control_var, scalar2, table_bits_var); + + pniels_t precmp_var[1<<table_bits_var]; + prepare_wnaf_table(precmp_var, base2, table_bits_var); + + int contp=0, contv=0, i = control_var[0].power; + + if (i < 0) { + curve448_point_copy(combo, curve448_point_identity); + return; + } else if (i > control_pre[0].power) { + pniels_to_pt(combo, precmp_var[control_var[0].addend >> 1]); + contv++; + } else if (i == control_pre[0].power && i >=0 ) { + pniels_to_pt(combo, precmp_var[control_var[0].addend >> 1]); + add_niels_to_pt(combo, curve448_wnaf_base[control_pre[0].addend >> 1], i); + contv++; contp++; + } else { + i = control_pre[0].power; + niels_to_pt(combo, curve448_wnaf_base[control_pre[0].addend >> 1]); + contp++; + } + + for (i--; i >= 0; i--) { + int cv = (i==control_var[contv].power), cp = (i==control_pre[contp].power); + point_double_internal(combo,combo,i && !(cv||cp)); + + if (cv) { + assert(control_var[contv].addend); + + if (control_var[contv].addend > 0) { + add_pniels_to_pt(combo, precmp_var[control_var[contv].addend >> 1], i&&!cp); + } else { + sub_pniels_from_pt(combo, precmp_var[(-control_var[contv].addend) >> 1], i&&!cp); + } + contv++; + } + + if (cp) { + assert(control_pre[contp].addend); + + if (control_pre[contp].addend > 0) { + add_niels_to_pt(combo, curve448_wnaf_base[control_pre[contp].addend >> 1], i); + } else { + sub_niels_from_pt(combo, curve448_wnaf_base[(-control_pre[contp].addend) >> 1], i); + } + contp++; + } + } + + /* This function is non-secret, but whatever this is cheap. */ + OPENSSL_cleanse(control_var,sizeof(control_var)); + OPENSSL_cleanse(control_pre,sizeof(control_pre)); + OPENSSL_cleanse(precmp_var,sizeof(precmp_var)); + + assert(contv == ncb_var); (void)ncb_var; + assert(contp == ncb_pre); (void)ncb_pre; +} + +void curve448_point_destroy ( + curve448_point_t point +) { + OPENSSL_cleanse(point, sizeof(curve448_point_t)); +} + +int X448(uint8_t out_shared_key[56], const uint8_t private_key[56], + const uint8_t peer_public_value[56]) +{ + return decaf_x448(out_shared_key, peer_public_value, private_key) + == DECAF_SUCCESS; +} + +void X448_public_from_private(uint8_t out_public_value[56], + const uint8_t private_key[56]) +{ + decaf_x448_derive_public_key(out_public_value, private_key); +} |