| #include <openssl/curve25519.h> |
| |
| #include <string.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]; |
| 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 */ |