Mercurial > dropbear
annotate libtommath/bn_mp_export.c @ 1505:55120acb9994
Add Spectre v2 mitigations for GCC (#54)
| author | Loganaden Velvindron <logan@hackers.mu> |
|---|---|
| date | Fri, 16 Feb 2018 19:35:32 +0400 |
| parents | 8bba51a55704 |
| children | f52919ffd3b1 |
| rev | line source |
|---|---|
| 1436 | 1 #include <tommath_private.h> |
| 2 #ifdef BN_MP_EXPORT_C | |
| 3 /* LibTomMath, multiple-precision integer library -- Tom St Denis | |
| 4 * | |
| 5 * LibTomMath is a library that provides multiple-precision | |
| 6 * integer arithmetic as well as number theoretic functionality. | |
| 7 * | |
| 8 * The library was designed directly after the MPI library by | |
| 9 * Michael Fromberger but has been written from scratch with | |
| 10 * additional optimizations in place. | |
| 11 * | |
| 12 * The library is free for all purposes without any express | |
| 13 * guarantee it works. | |
| 14 * | |
| 15 * Tom St Denis, [email protected], http://libtom.org | |
| 16 */ | |
| 17 | |
| 18 /* based on gmp's mpz_export. | |
| 19 * see http://gmplib.org/manual/Integer-Import-and-Export.html | |
| 20 */ | |
| 21 int mp_export(void* rop, size_t* countp, int order, size_t size, | |
| 22 int endian, size_t nails, mp_int* op) { | |
| 23 int result; | |
| 24 size_t odd_nails, nail_bytes, i, j, bits, count; | |
| 25 unsigned char odd_nail_mask; | |
| 26 | |
| 27 mp_int t; | |
| 28 | |
| 29 if ((result = mp_init_copy(&t, op)) != MP_OKAY) { | |
| 30 return result; | |
| 31 } | |
| 32 | |
| 33 if (endian == 0) { | |
| 34 union { | |
| 35 unsigned int i; | |
| 36 char c[4]; | |
| 37 } lint; | |
| 38 lint.i = 0x01020304; | |
| 39 | |
| 40 endian = (lint.c[0] == 4) ? -1 : 1; | |
| 41 } | |
| 42 | |
| 43 odd_nails = (nails % 8); | |
| 44 odd_nail_mask = 0xff; | |
| 45 for (i = 0; i < odd_nails; ++i) { | |
| 46 odd_nail_mask ^= (1 << (7 - i)); | |
| 47 } | |
| 48 nail_bytes = nails / 8; | |
| 49 | |
| 50 bits = mp_count_bits(&t); | |
| 51 count = (bits / ((size * 8) - nails)) + (((bits % ((size * 8) - nails)) != 0) ? 1 : 0); | |
| 52 | |
| 53 for (i = 0; i < count; ++i) { | |
| 54 for (j = 0; j < size; ++j) { | |
| 55 unsigned char* byte = ( | |
| 56 (unsigned char*)rop + | |
| 57 (((order == -1) ? i : ((count - 1) - i)) * size) + | |
| 58 ((endian == -1) ? j : ((size - 1) - j)) | |
| 59 ); | |
| 60 | |
| 61 if (j >= (size - nail_bytes)) { | |
| 62 *byte = 0; | |
| 63 continue; | |
| 64 } | |
| 65 | |
| 66 *byte = (unsigned char)((j == ((size - nail_bytes) - 1)) ? (t.dp[0] & odd_nail_mask) : (t.dp[0] & 0xFF)); | |
| 67 | |
| 68 if ((result = mp_div_2d(&t, ((j == ((size - nail_bytes) - 1)) ? (8 - odd_nails) : 8), &t, NULL)) != MP_OKAY) { | |
| 69 mp_clear(&t); | |
| 70 return result; | |
| 71 } | |
| 72 } | |
| 73 } | |
| 74 | |
| 75 mp_clear(&t); | |
| 76 | |
| 77 if (countp != NULL) { | |
| 78 *countp = count; | |
| 79 } | |
| 80 | |
| 81 return MP_OKAY; | |
| 82 } | |
| 83 | |
| 84 #endif | |
| 85 | |
|
1470
8bba51a55704
Update to libtommath v1.0.1
Matt Johnston <matt@ucc.asn.au>
parents:
1436
diff
changeset
|
86 /* ref: $Format:%D$ */ |
|
8bba51a55704
Update to libtommath v1.0.1
Matt Johnston <matt@ucc.asn.au>
parents:
1436
diff
changeset
|
87 /* git commit: $Format:%H$ */ |
|
8bba51a55704
Update to libtommath v1.0.1
Matt Johnston <matt@ucc.asn.au>
parents:
1436
diff
changeset
|
88 /* commit time: $Format:%ai$ */ |