77a173efed
This assembly is in gas syntax so is not built on Windows nor when OPENSSL_SMALL is defined. Change-Id: I1050cf1b16350fd4b758e4c463261b30a1b65390 Reviewed-on: https://boringssl-review.googlesource.com/6782 Reviewed-by: Adam Langley <agl@google.com>
226 lines
6.7 KiB
C
226 lines
6.7 KiB
C
#include <openssl/curve25519.h>
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#include <string.h>
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#include "internal.h"
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#if defined(BORINGSSL_X25519_X86_64)
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typedef struct { uint64_t v[5]; } fe25519;
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/* These functions are defined in asm/x25519-x86_64.S */
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void x25519_x86_64_work_cswap(fe25519 *, uint64_t);
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void x25519_x86_64_mul(fe25519 *out, const fe25519 *a, const fe25519 *b);
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void x25519_x86_64_square(fe25519 *out, const fe25519 *a);
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void x25519_x86_64_freeze(fe25519 *);
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void x25519_x86_64_ladderstep(fe25519 *work);
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static void fe25519_setint(fe25519 *r, unsigned v) {
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r->v[0] = v;
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r->v[1] = 0;
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r->v[2] = 0;
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r->v[3] = 0;
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r->v[4] = 0;
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}
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/* Assumes input x being reduced below 2^255 */
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static void fe25519_pack(unsigned char r[32], const fe25519 *x) {
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fe25519 t;
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t = *x;
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x25519_x86_64_freeze(&t);
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r[0] = (uint8_t)(t.v[0] & 0xff);
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r[1] = (uint8_t)((t.v[0] >> 8) & 0xff);
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r[2] = (uint8_t)((t.v[0] >> 16) & 0xff);
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r[3] = (uint8_t)((t.v[0] >> 24) & 0xff);
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r[4] = (uint8_t)((t.v[0] >> 32) & 0xff);
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r[5] = (uint8_t)((t.v[0] >> 40) & 0xff);
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r[6] = (uint8_t)((t.v[0] >> 48));
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r[6] ^= (uint8_t)((t.v[1] << 3) & 0xf8);
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r[7] = (uint8_t)((t.v[1] >> 5) & 0xff);
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r[8] = (uint8_t)((t.v[1] >> 13) & 0xff);
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r[9] = (uint8_t)((t.v[1] >> 21) & 0xff);
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r[10] = (uint8_t)((t.v[1] >> 29) & 0xff);
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r[11] = (uint8_t)((t.v[1] >> 37) & 0xff);
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r[12] = (uint8_t)((t.v[1] >> 45));
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r[12] ^= (uint8_t)((t.v[2] << 6) & 0xc0);
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r[13] = (uint8_t)((t.v[2] >> 2) & 0xff);
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r[14] = (uint8_t)((t.v[2] >> 10) & 0xff);
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r[15] = (uint8_t)((t.v[2] >> 18) & 0xff);
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r[16] = (uint8_t)((t.v[2] >> 26) & 0xff);
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r[17] = (uint8_t)((t.v[2] >> 34) & 0xff);
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r[18] = (uint8_t)((t.v[2] >> 42) & 0xff);
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r[19] = (uint8_t)((t.v[2] >> 50));
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r[19] ^= (uint8_t)((t.v[3] << 1) & 0xfe);
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r[20] = (uint8_t)((t.v[3] >> 7) & 0xff);
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r[21] = (uint8_t)((t.v[3] >> 15) & 0xff);
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r[22] = (uint8_t)((t.v[3] >> 23) & 0xff);
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r[23] = (uint8_t)((t.v[3] >> 31) & 0xff);
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r[24] = (uint8_t)((t.v[3] >> 39) & 0xff);
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r[25] = (uint8_t)((t.v[3] >> 47));
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r[25] ^= (uint8_t)((t.v[4] << 4) & 0xf0);
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r[26] = (uint8_t)((t.v[4] >> 4) & 0xff);
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r[27] = (uint8_t)((t.v[4] >> 12) & 0xff);
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r[28] = (uint8_t)((t.v[4] >> 20) & 0xff);
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r[29] = (uint8_t)((t.v[4] >> 28) & 0xff);
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r[30] = (uint8_t)((t.v[4] >> 36) & 0xff);
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r[31] = (uint8_t)((t.v[4] >> 44));
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}
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static void fe25519_unpack(fe25519 *r, const uint8_t x[32]) {
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r->v[0] = x[0];
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r->v[0] += (uint64_t)x[1] << 8;
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r->v[0] += (uint64_t)x[2] << 16;
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r->v[0] += (uint64_t)x[3] << 24;
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r->v[0] += (uint64_t)x[4] << 32;
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r->v[0] += (uint64_t)x[5] << 40;
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r->v[0] += ((uint64_t)x[6] & 7) << 48;
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r->v[1] = x[6] >> 3;
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r->v[1] += (uint64_t)x[7] << 5;
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r->v[1] += (uint64_t)x[8] << 13;
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r->v[1] += (uint64_t)x[9] << 21;
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r->v[1] += (uint64_t)x[10] << 29;
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r->v[1] += (uint64_t)x[11] << 37;
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r->v[1] += ((uint64_t)x[12] & 63) << 45;
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r->v[2] = x[12] >> 6;
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r->v[2] += (uint64_t)x[13] << 2;
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r->v[2] += (uint64_t)x[14] << 10;
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r->v[2] += (uint64_t)x[15] << 18;
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r->v[2] += (uint64_t)x[16] << 26;
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r->v[2] += (uint64_t)x[17] << 34;
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r->v[2] += (uint64_t)x[18] << 42;
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r->v[2] += ((uint64_t)x[19] & 1) << 50;
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r->v[3] = x[19] >> 1;
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r->v[3] += (uint64_t)x[20] << 7;
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r->v[3] += (uint64_t)x[21] << 15;
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r->v[3] += (uint64_t)x[22] << 23;
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r->v[3] += (uint64_t)x[23] << 31;
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r->v[3] += (uint64_t)x[24] << 39;
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r->v[3] += ((uint64_t)x[25] & 15) << 47;
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r->v[4] = x[25] >> 4;
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r->v[4] += (uint64_t)x[26] << 4;
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r->v[4] += (uint64_t)x[27] << 12;
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r->v[4] += (uint64_t)x[28] << 20;
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r->v[4] += (uint64_t)x[29] << 28;
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r->v[4] += (uint64_t)x[30] << 36;
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r->v[4] += ((uint64_t)x[31] & 127) << 44;
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}
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static void fe25519_invert(fe25519 *r, const fe25519 *x) {
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fe25519 z2;
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fe25519 z9;
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fe25519 z11;
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fe25519 z2_5_0;
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fe25519 z2_10_0;
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fe25519 z2_20_0;
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fe25519 z2_50_0;
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fe25519 z2_100_0;
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fe25519 t;
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int i;
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/* 2 */ x25519_x86_64_square(&z2, x);
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/* 4 */ x25519_x86_64_square(&t, &z2);
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/* 8 */ x25519_x86_64_square(&t, &t);
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/* 9 */ x25519_x86_64_mul(&z9, &t, x);
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/* 11 */ x25519_x86_64_mul(&z11, &z9, &z2);
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/* 22 */ x25519_x86_64_square(&t, &z11);
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/* 2^5 - 2^0 = 31 */ x25519_x86_64_mul(&z2_5_0, &t, &z9);
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/* 2^6 - 2^1 */ x25519_x86_64_square(&t, &z2_5_0);
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/* 2^20 - 2^10 */ for (i = 1; i < 5; i++) { x25519_x86_64_square(&t, &t); }
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/* 2^10 - 2^0 */ x25519_x86_64_mul(&z2_10_0, &t, &z2_5_0);
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/* 2^11 - 2^1 */ x25519_x86_64_square(&t, &z2_10_0);
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/* 2^20 - 2^10 */ for (i = 1; i < 10; i++) { x25519_x86_64_square(&t, &t); }
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/* 2^20 - 2^0 */ x25519_x86_64_mul(&z2_20_0, &t, &z2_10_0);
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/* 2^21 - 2^1 */ x25519_x86_64_square(&t, &z2_20_0);
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/* 2^40 - 2^20 */ for (i = 1; i < 20; i++) { x25519_x86_64_square(&t, &t); }
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/* 2^40 - 2^0 */ x25519_x86_64_mul(&t, &t, &z2_20_0);
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/* 2^41 - 2^1 */ x25519_x86_64_square(&t, &t);
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/* 2^50 - 2^10 */ for (i = 1; i < 10; i++) { x25519_x86_64_square(&t, &t); }
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/* 2^50 - 2^0 */ x25519_x86_64_mul(&z2_50_0, &t, &z2_10_0);
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/* 2^51 - 2^1 */ x25519_x86_64_square(&t, &z2_50_0);
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/* 2^100 - 2^50 */ for (i = 1; i < 50; i++) { x25519_x86_64_square(&t, &t); }
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/* 2^100 - 2^0 */ x25519_x86_64_mul(&z2_100_0, &t, &z2_50_0);
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/* 2^101 - 2^1 */ x25519_x86_64_square(&t, &z2_100_0);
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/* 2^200 - 2^100 */ for (i = 1; i < 100; i++) {
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x25519_x86_64_square(&t, &t);
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}
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/* 2^200 - 2^0 */ x25519_x86_64_mul(&t, &t, &z2_100_0);
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/* 2^201 - 2^1 */ x25519_x86_64_square(&t, &t);
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/* 2^250 - 2^50 */ for (i = 1; i < 50; i++) { x25519_x86_64_square(&t, &t); }
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/* 2^250 - 2^0 */ x25519_x86_64_mul(&t, &t, &z2_50_0);
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/* 2^251 - 2^1 */ x25519_x86_64_square(&t, &t);
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/* 2^252 - 2^2 */ x25519_x86_64_square(&t, &t);
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/* 2^253 - 2^3 */ x25519_x86_64_square(&t, &t);
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/* 2^254 - 2^4 */ x25519_x86_64_square(&t, &t);
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/* 2^255 - 2^5 */ x25519_x86_64_square(&t, &t);
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/* 2^255 - 21 */ x25519_x86_64_mul(r, &t, &z11);
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}
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static void mladder(fe25519 *xr, fe25519 *zr, const uint8_t s[32]) {
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fe25519 work[5];
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work[0] = *xr;
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fe25519_setint(work + 1, 1);
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fe25519_setint(work + 2, 0);
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work[3] = *xr;
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fe25519_setint(work + 4, 1);
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int i, j;
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uint8_t prevbit = 0;
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j = 6;
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for (i = 31; i >= 0; i--) {
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while (j >= 0) {
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const uint8_t bit = 1 & (s[i] >> j);
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const uint64_t swap = bit ^ prevbit;
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prevbit = bit;
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x25519_x86_64_work_cswap(work + 1, swap);
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x25519_x86_64_ladderstep(work);
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j -= 1;
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}
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j = 7;
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}
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*xr = work[1];
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*zr = work[2];
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}
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void x25519_x86_64(uint8_t out[32], const uint8_t scalar[32],
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const uint8_t point[32]) {
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uint8_t e[32];
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memcpy(e, scalar, sizeof(e));
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e[0] &= 248;
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e[31] &= 127;
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e[31] |= 64;
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fe25519 t;
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fe25519 z;
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fe25519_unpack(&t, point);
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mladder(&t, &z, e);
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fe25519_invert(&z, &z);
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x25519_x86_64_mul(&t, &t, &z);
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fe25519_pack(out, &t);
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}
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#endif /* BORINGSSL_X25519_X86_64 */
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