/* Copyright (c) 2015, Google Inc. * * Permission to use, copy, modify, and/or distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ // This code is mostly taken from the ref10 version of Ed25519 in SUPERCOP // 20141124 (http://bench.cr.yp.to/supercop.html). That code is released as // public domain but this file has the ISC license just to keep licencing // simple. // // The field functions are shared by Ed25519 and X25519 where possible. #include #include #include "../internal.h" #include "internal.h" #if defined(BORINGSSL_X25519_X86_64) typedef struct { uint64_t v[5]; } fe25519; // These functions are defined in asm/x25519-x86_64.S void x25519_x86_64_work_cswap(fe25519 *, uint64_t); void x25519_x86_64_mul(fe25519 *out, const fe25519 *a, const fe25519 *b); void x25519_x86_64_square(fe25519 *out, const fe25519 *a); void x25519_x86_64_freeze(fe25519 *); void x25519_x86_64_ladderstep(fe25519 *work); static void fe25519_setint(fe25519 *r, unsigned v) { r->v[0] = v; r->v[1] = 0; r->v[2] = 0; r->v[3] = 0; r->v[4] = 0; } // Assumes input x being reduced below 2^255 static void fe25519_pack(unsigned char r[32], const fe25519 *x) { fe25519 t; t = *x; x25519_x86_64_freeze(&t); r[0] = (uint8_t)(t.v[0] & 0xff); r[1] = (uint8_t)((t.v[0] >> 8) & 0xff); r[2] = (uint8_t)((t.v[0] >> 16) & 0xff); r[3] = (uint8_t)((t.v[0] >> 24) & 0xff); r[4] = (uint8_t)((t.v[0] >> 32) & 0xff); r[5] = (uint8_t)((t.v[0] >> 40) & 0xff); r[6] = (uint8_t)((t.v[0] >> 48)); r[6] ^= (uint8_t)((t.v[1] << 3) & 0xf8); r[7] = (uint8_t)((t.v[1] >> 5) & 0xff); r[8] = (uint8_t)((t.v[1] >> 13) & 0xff); r[9] = (uint8_t)((t.v[1] >> 21) & 0xff); r[10] = (uint8_t)((t.v[1] >> 29) & 0xff); r[11] = (uint8_t)((t.v[1] >> 37) & 0xff); r[12] = (uint8_t)((t.v[1] >> 45)); r[12] ^= (uint8_t)((t.v[2] << 6) & 0xc0); r[13] = (uint8_t)((t.v[2] >> 2) & 0xff); r[14] = (uint8_t)((t.v[2] >> 10) & 0xff); r[15] = (uint8_t)((t.v[2] >> 18) & 0xff); r[16] = (uint8_t)((t.v[2] >> 26) & 0xff); r[17] = (uint8_t)((t.v[2] >> 34) & 0xff); r[18] = (uint8_t)((t.v[2] >> 42) & 0xff); r[19] = (uint8_t)((t.v[2] >> 50)); r[19] ^= (uint8_t)((t.v[3] << 1) & 0xfe); r[20] = (uint8_t)((t.v[3] >> 7) & 0xff); r[21] = (uint8_t)((t.v[3] >> 15) & 0xff); r[22] = (uint8_t)((t.v[3] >> 23) & 0xff); r[23] = (uint8_t)((t.v[3] >> 31) & 0xff); r[24] = (uint8_t)((t.v[3] >> 39) & 0xff); r[25] = (uint8_t)((t.v[3] >> 47)); r[25] ^= (uint8_t)((t.v[4] << 4) & 0xf0); r[26] = (uint8_t)((t.v[4] >> 4) & 0xff); r[27] = (uint8_t)((t.v[4] >> 12) & 0xff); r[28] = (uint8_t)((t.v[4] >> 20) & 0xff); r[29] = (uint8_t)((t.v[4] >> 28) & 0xff); r[30] = (uint8_t)((t.v[4] >> 36) & 0xff); r[31] = (uint8_t)((t.v[4] >> 44)); } static void fe25519_unpack(fe25519 *r, const uint8_t x[32]) { r->v[0] = x[0]; r->v[0] += (uint64_t)x[1] << 8; r->v[0] += (uint64_t)x[2] << 16; r->v[0] += (uint64_t)x[3] << 24; r->v[0] += (uint64_t)x[4] << 32; r->v[0] += (uint64_t)x[5] << 40; r->v[0] += ((uint64_t)x[6] & 7) << 48; r->v[1] = x[6] >> 3; r->v[1] += (uint64_t)x[7] << 5; r->v[1] += (uint64_t)x[8] << 13; r->v[1] += (uint64_t)x[9] << 21; r->v[1] += (uint64_t)x[10] << 29; r->v[1] += (uint64_t)x[11] << 37; r->v[1] += ((uint64_t)x[12] & 63) << 45; r->v[2] = x[12] >> 6; r->v[2] += (uint64_t)x[13] << 2; r->v[2] += (uint64_t)x[14] << 10; r->v[2] += (uint64_t)x[15] << 18; r->v[2] += (uint64_t)x[16] << 26; r->v[2] += (uint64_t)x[17] << 34; r->v[2] += (uint64_t)x[18] << 42; r->v[2] += ((uint64_t)x[19] & 1) << 50; r->v[3] = x[19] >> 1; r->v[3] += (uint64_t)x[20] << 7; r->v[3] += (uint64_t)x[21] << 15; r->v[3] += (uint64_t)x[22] << 23; r->v[3] += (uint64_t)x[23] << 31; r->v[3] += (uint64_t)x[24] << 39; r->v[3] += ((uint64_t)x[25] & 15) << 47; r->v[4] = x[25] >> 4; r->v[4] += (uint64_t)x[26] << 4; r->v[4] += (uint64_t)x[27] << 12; r->v[4] += (uint64_t)x[28] << 20; r->v[4] += (uint64_t)x[29] << 28; r->v[4] += (uint64_t)x[30] << 36; r->v[4] += ((uint64_t)x[31] & 127) << 44; } static void fe25519_invert(fe25519 *r, const fe25519 *x) { fe25519 z2; fe25519 z9; fe25519 z11; fe25519 z2_5_0; fe25519 z2_10_0; fe25519 z2_20_0; fe25519 z2_50_0; fe25519 z2_100_0; fe25519 t; int i; /* 2 */ x25519_x86_64_square(&z2, x); /* 4 */ x25519_x86_64_square(&t, &z2); /* 8 */ x25519_x86_64_square(&t, &t); /* 9 */ x25519_x86_64_mul(&z9, &t, x); /* 11 */ x25519_x86_64_mul(&z11, &z9, &z2); /* 22 */ x25519_x86_64_square(&t, &z11); /* 2^5 - 2^0 = 31 */ x25519_x86_64_mul(&z2_5_0, &t, &z9); /* 2^6 - 2^1 */ x25519_x86_64_square(&t, &z2_5_0); /* 2^20 - 2^10 */ for (i = 1; i < 5; i++) { x25519_x86_64_square(&t, &t); } /* 2^10 - 2^0 */ x25519_x86_64_mul(&z2_10_0, &t, &z2_5_0); /* 2^11 - 2^1 */ x25519_x86_64_square(&t, &z2_10_0); /* 2^20 - 2^10 */ for (i = 1; i < 10; i++) { x25519_x86_64_square(&t, &t); } /* 2^20 - 2^0 */ x25519_x86_64_mul(&z2_20_0, &t, &z2_10_0); /* 2^21 - 2^1 */ x25519_x86_64_square(&t, &z2_20_0); /* 2^40 - 2^20 */ for (i = 1; i < 20; i++) { x25519_x86_64_square(&t, &t); } /* 2^40 - 2^0 */ x25519_x86_64_mul(&t, &t, &z2_20_0); /* 2^41 - 2^1 */ x25519_x86_64_square(&t, &t); /* 2^50 - 2^10 */ for (i = 1; i < 10; i++) { x25519_x86_64_square(&t, &t); } /* 2^50 - 2^0 */ x25519_x86_64_mul(&z2_50_0, &t, &z2_10_0); /* 2^51 - 2^1 */ x25519_x86_64_square(&t, &z2_50_0); /* 2^100 - 2^50 */ for (i = 1; i < 50; i++) { x25519_x86_64_square(&t, &t); } /* 2^100 - 2^0 */ x25519_x86_64_mul(&z2_100_0, &t, &z2_50_0); /* 2^101 - 2^1 */ x25519_x86_64_square(&t, &z2_100_0); /* 2^200 - 2^100 */ for (i = 1; i < 100; i++) { x25519_x86_64_square(&t, &t); } /* 2^200 - 2^0 */ x25519_x86_64_mul(&t, &t, &z2_100_0); /* 2^201 - 2^1 */ x25519_x86_64_square(&t, &t); /* 2^250 - 2^50 */ for (i = 1; i < 50; i++) { x25519_x86_64_square(&t, &t); } /* 2^250 - 2^0 */ x25519_x86_64_mul(&t, &t, &z2_50_0); /* 2^251 - 2^1 */ x25519_x86_64_square(&t, &t); /* 2^252 - 2^2 */ x25519_x86_64_square(&t, &t); /* 2^253 - 2^3 */ x25519_x86_64_square(&t, &t); /* 2^254 - 2^4 */ x25519_x86_64_square(&t, &t); /* 2^255 - 2^5 */ x25519_x86_64_square(&t, &t); /* 2^255 - 21 */ x25519_x86_64_mul(r, &t, &z11); } static void mladder(fe25519 *xr, fe25519 *zr, const uint8_t s[32]) { fe25519 work[5]; work[0] = *xr; fe25519_setint(work + 1, 1); fe25519_setint(work + 2, 0); work[3] = *xr; fe25519_setint(work + 4, 1); int i, j; uint8_t prevbit = 0; j = 6; for (i = 31; i >= 0; i--) { while (j >= 0) { const uint8_t bit = 1 & (s[i] >> j); const uint64_t swap = bit ^ prevbit; prevbit = bit; x25519_x86_64_work_cswap(work + 1, swap); x25519_x86_64_ladderstep(work); j -= 1; } j = 7; } *xr = work[1]; *zr = work[2]; } void x25519_x86_64(uint8_t out[32], const uint8_t scalar[32], const uint8_t point[32]) { uint8_t e[32]; OPENSSL_memcpy(e, scalar, sizeof(e)); e[0] &= 248; e[31] &= 127; e[31] |= 64; fe25519 t; fe25519 z; fe25519_unpack(&t, point); mladder(&t, &z, e); fe25519_invert(&z, &z); x25519_x86_64_mul(&t, &t, &z); fe25519_pack(out, &t); } #endif // BORINGSSL_X25519_X86_64