diff options
Diffstat (limited to 'third_party/heimdal/lib/hcrypto/x25519/x25519_ref10.c')
| -rw-r--r-- | third_party/heimdal/lib/hcrypto/x25519/x25519_ref10.c | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/third_party/heimdal/lib/hcrypto/x25519/x25519_ref10.c b/third_party/heimdal/lib/hcrypto/x25519/x25519_ref10.c new file mode 100644 index 0000000..d6fced7 --- /dev/null +++ b/third_party/heimdal/lib/hcrypto/x25519/x25519_ref10.c @@ -0,0 +1,209 @@ +/* + * ISC License + * + * Copyright (c) 2013-2019 + * Frank Denis <j at pureftpd dot org> + * + * 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. + */ + +#include <stddef.h> +#include <stdint.h> + +#include "ed25519_ref10.h" +#include "x25519_ref10.h" +#include "align.h" + +/* + * Reject small order points early to mitigate the implications of + * unexpected optimizations that would affect the ref10 code. + * See https://eprint.iacr.org/2017/806.pdf for reference. + */ +static int +has_small_order(const unsigned char s[32]) +{ + CRYPTO_ALIGN(16) + static const unsigned char blacklist[][32] = { + /* 0 (order 4) */ + { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, + /* 1 (order 1) */ + { 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, + /* 325606250916557431795983626356110631294008115727848805560023387167927233504 + (order 8) */ + { 0xe0, 0xeb, 0x7a, 0x7c, 0x3b, 0x41, 0xb8, 0xae, 0x16, 0x56, 0xe3, + 0xfa, 0xf1, 0x9f, 0xc4, 0x6a, 0xda, 0x09, 0x8d, 0xeb, 0x9c, 0x32, + 0xb1, 0xfd, 0x86, 0x62, 0x05, 0x16, 0x5f, 0x49, 0xb8, 0x00 }, + /* 39382357235489614581723060781553021112529911719440698176882885853963445705823 + (order 8) */ + { 0x5f, 0x9c, 0x95, 0xbc, 0xa3, 0x50, 0x8c, 0x24, 0xb1, 0xd0, 0xb1, + 0x55, 0x9c, 0x83, 0xef, 0x5b, 0x04, 0x44, 0x5c, 0xc4, 0x58, 0x1c, + 0x8e, 0x86, 0xd8, 0x22, 0x4e, 0xdd, 0xd0, 0x9f, 0x11, 0x57 }, + /* p-1 (order 2) */ + { 0xec, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f }, + /* p (=0, order 4) */ + { 0xed, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f }, + /* p+1 (=1, order 1) */ + { 0xee, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f } + }; + unsigned char c[7] = { 0 }; + unsigned int k; + size_t i, j; + +#define COMPILER_ASSERT(X) (void) sizeof(char[(X) ? 1 : -1]) + + COMPILER_ASSERT(7 == sizeof blacklist / sizeof blacklist[0]); + for (j = 0; j < 31; j++) { + for (i = 0; i < sizeof blacklist / sizeof blacklist[0]; i++) { + c[i] |= s[j] ^ blacklist[i][j]; + } + } + for (i = 0; i < sizeof blacklist / sizeof blacklist[0]; i++) { + c[i] |= (s[j] & 0x7f) ^ blacklist[i][j]; + } + k = 0; + for (i = 0; i < sizeof blacklist / sizeof blacklist[0]; i++) { + k |= (c[i] - 1); + } + return (int) ((k >> 8) & 1); +} + +static int +crypto_scalarmult_curve25519_ref10(unsigned char *q, + const unsigned char *n, + const unsigned char *p) +{ + unsigned char *t = q; + unsigned int i; + fe25519 x1; + fe25519 x2; + fe25519 z2; + fe25519 x3; + fe25519 z3; + fe25519 tmp0; + fe25519 tmp1; + int pos; + unsigned int swap; + unsigned int b; + + if (has_small_order(p)) { + return -1; + } + for (i = 0; i < 32; i++) { + t[i] = n[i]; + } + t[0] &= 248; + t[31] &= 127; + t[31] |= 64; + fe25519_frombytes(x1, p); + fe25519_1(x2); + fe25519_0(z2); + fe25519_copy(x3, x1); + fe25519_1(z3); + + swap = 0; + for (pos = 254; pos >= 0; --pos) { + b = t[pos / 8] >> (pos & 7); + b &= 1; + swap ^= b; + fe25519_cswap(x2, x3, swap); + fe25519_cswap(z2, z3, swap); + swap = b; + fe25519_sub(tmp0, x3, z3); + fe25519_sub(tmp1, x2, z2); + fe25519_add(x2, x2, z2); + fe25519_add(z2, x3, z3); + fe25519_mul(z3, tmp0, x2); + fe25519_mul(z2, z2, tmp1); + fe25519_sq(tmp0, tmp1); + fe25519_sq(tmp1, x2); + fe25519_add(x3, z3, z2); + fe25519_sub(z2, z3, z2); + fe25519_mul(x2, tmp1, tmp0); + fe25519_sub(tmp1, tmp1, tmp0); + fe25519_sq(z2, z2); + fe25519_scalar_product(z3, tmp1, 121666); + fe25519_sq(x3, x3); + fe25519_add(tmp0, tmp0, z3); + fe25519_mul(z3, x1, z2); + fe25519_mul(z2, tmp1, tmp0); + } + fe25519_cswap(x2, x3, swap); + fe25519_cswap(z2, z3, swap); + + fe25519_invert(z2, z2); + fe25519_mul(x2, x2, z2); + fe25519_tobytes(q, x2); + + return 0; +} + +static void +edwards_to_montgomery(fe25519 montgomeryX, const fe25519 edwardsY, const fe25519 edwardsZ) +{ + fe25519 tempX; + fe25519 tempZ; + + fe25519_add(tempX, edwardsZ, edwardsY); + fe25519_sub(tempZ, edwardsZ, edwardsY); + fe25519_invert(tempZ, tempZ); + fe25519_mul(montgomeryX, tempX, tempZ); +} + +int +crypto_scalarmult_curve25519_base(unsigned char *q, + const unsigned char *n) +{ + unsigned char *t = q; + ge25519_p3 A; + fe25519 pk; + unsigned int i; + + for (i = 0; i < 32; i++) { + t[i] = n[i]; + } + t[0] &= 248; + t[31] &= 127; + t[31] |= 64; + ge25519_scalarmult_base(&A, t); + edwards_to_montgomery(pk, A.Y, A.Z); + fe25519_tobytes(q, pk); + + return 0; +} + +int +crypto_scalarmult_curve25519(unsigned char *q, const unsigned char *n, + const unsigned char *p) +{ + size_t i; + volatile unsigned char d = 0; + + if (crypto_scalarmult_curve25519_ref10(q, n, p) != 0) { + return -1; /* LCOV_EXCL_LINE */ + } + for (i = 0; i < crypto_scalarmult_curve25519_BYTES; i++) { + d |= q[i]; + } + return -(1 & ((d - 1) >> 8)); +} + |