-#define _GNU_SOURCE
+/*
+ * Shamir's secret sharing implementation
+ *
+ * Copyright (C) 2013 Matt Corallo <git@bluematt.me>
+ *
+ * This file is part of ASSS (Audit-friendly Shamir's Secret Sharing)
+ *
+ * ASSS is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * ASSS is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public
+ * License along with ASSS. If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
-#include <stdint.h>
-#include <stdio.h>
+#ifndef IN_KERNEL
#include <assert.h>
-#include <string.h>
-#include <unistd.h>
-#include <stdlib.h>
-#include <sys/mman.h>
+#define CHECKSTATE(x) assert(x)
+#else
+#include <linux/bug.h>
+#define CHECKSTATE(x) BUG_ON(!(x))
+#endif
+
+#include "shamirssecret.h"
-#define MAX_LENGTH 1024
+#ifndef noinline
+#define noinline __attribute__((noinline))
+#endif
/*
- * Calculations across the finite field GF(p)
- * Lots of side-channel attacks in here
+ * Calculations across the finite field GF(2^8)
*/
-/*
-const uint8_t p = 251; // Largest 8-bit prime
+
+#ifndef TEST
static uint8_t field_add(uint8_t a, uint8_t b) {
- assert(a < p && b < p);
- return (((uint16_t)a) + ((uint16_t)b)) % p;
+ return a ^ b;
}
static uint8_t field_sub(uint8_t a, uint8_t b) {
- assert(a < p && b < p);
- return (((uint16_t)p) + ((uint16_t)a) - ((uint16_t)b)) % p;
+ return a ^ b;
}
-static uint8_t field_mul(uint8_t a, uint8_t b) {
- assert(a < p && b < p);
- return (((uint16_t)a) * ((uint16_t)b)) % p;
+static uint8_t field_neg(uint8_t a) {
+ return field_sub(0, a);
}
-
-static uint8_t field_pow(uint8_t a, uint8_t e) {
- assert(a < p);
- uint8_t ret = 1;
- for (uint8_t i = 0; i < e; i++) {
- ret = field_mul(ret, a);
- }
+#endif
+
+//TODO: Using static tables will very likely create side-channel attacks when measuring cache hits
+// Because these are fairly small tables, we can probably get them loaded mostly/fully into
+// cache before use to break such attacks.
+static const uint8_t exp[P] = {
+ 0x01, 0x03, 0x05, 0x0f, 0x11, 0x33, 0x55, 0xff, 0x1a, 0x2e, 0x72, 0x96, 0xa1, 0xf8, 0x13, 0x35,
+ 0x5f, 0xe1, 0x38, 0x48, 0xd8, 0x73, 0x95, 0xa4, 0xf7, 0x02, 0x06, 0x0a, 0x1e, 0x22, 0x66, 0xaa,
+ 0xe5, 0x34, 0x5c, 0xe4, 0x37, 0x59, 0xeb, 0x26, 0x6a, 0xbe, 0xd9, 0x70, 0x90, 0xab, 0xe6, 0x31,
+ 0x53, 0xf5, 0x04, 0x0c, 0x14, 0x3c, 0x44, 0xcc, 0x4f, 0xd1, 0x68, 0xb8, 0xd3, 0x6e, 0xb2, 0xcd,
+ 0x4c, 0xd4, 0x67, 0xa9, 0xe0, 0x3b, 0x4d, 0xd7, 0x62, 0xa6, 0xf1, 0x08, 0x18, 0x28, 0x78, 0x88,
+ 0x83, 0x9e, 0xb9, 0xd0, 0x6b, 0xbd, 0xdc, 0x7f, 0x81, 0x98, 0xb3, 0xce, 0x49, 0xdb, 0x76, 0x9a,
+ 0xb5, 0xc4, 0x57, 0xf9, 0x10, 0x30, 0x50, 0xf0, 0x0b, 0x1d, 0x27, 0x69, 0xbb, 0xd6, 0x61, 0xa3,
+ 0xfe, 0x19, 0x2b, 0x7d, 0x87, 0x92, 0xad, 0xec, 0x2f, 0x71, 0x93, 0xae, 0xe9, 0x20, 0x60, 0xa0,
+ 0xfb, 0x16, 0x3a, 0x4e, 0xd2, 0x6d, 0xb7, 0xc2, 0x5d, 0xe7, 0x32, 0x56, 0xfa, 0x15, 0x3f, 0x41,
+ 0xc3, 0x5e, 0xe2, 0x3d, 0x47, 0xc9, 0x40, 0xc0, 0x5b, 0xed, 0x2c, 0x74, 0x9c, 0xbf, 0xda, 0x75,
+ 0x9f, 0xba, 0xd5, 0x64, 0xac, 0xef, 0x2a, 0x7e, 0x82, 0x9d, 0xbc, 0xdf, 0x7a, 0x8e, 0x89, 0x80,
+ 0x9b, 0xb6, 0xc1, 0x58, 0xe8, 0x23, 0x65, 0xaf, 0xea, 0x25, 0x6f, 0xb1, 0xc8, 0x43, 0xc5, 0x54,
+ 0xfc, 0x1f, 0x21, 0x63, 0xa5, 0xf4, 0x07, 0x09, 0x1b, 0x2d, 0x77, 0x99, 0xb0, 0xcb, 0x46, 0xca,
+ 0x45, 0xcf, 0x4a, 0xde, 0x79, 0x8b, 0x86, 0x91, 0xa8, 0xe3, 0x3e, 0x42, 0xc6, 0x51, 0xf3, 0x0e,
+ 0x12, 0x36, 0x5a, 0xee, 0x29, 0x7b, 0x8d, 0x8c, 0x8f, 0x8a, 0x85, 0x94, 0xa7, 0xf2, 0x0d, 0x17,
+ 0x39, 0x4b, 0xdd, 0x7c, 0x84, 0x97, 0xa2, 0xfd, 0x1c, 0x24, 0x6c, 0xb4, 0xc7, 0x52, 0xf6, 0x01};
+static const uint8_t log[P] = {
+ 0x00, // log(0) is not defined
+ 0xff, 0x19, 0x01, 0x32, 0x02, 0x1a, 0xc6, 0x4b, 0xc7, 0x1b, 0x68, 0x33, 0xee, 0xdf, 0x03, 0x64,
+ 0x04, 0xe0, 0x0e, 0x34, 0x8d, 0x81, 0xef, 0x4c, 0x71, 0x08, 0xc8, 0xf8, 0x69, 0x1c, 0xc1, 0x7d,
+ 0xc2, 0x1d, 0xb5, 0xf9, 0xb9, 0x27, 0x6a, 0x4d, 0xe4, 0xa6, 0x72, 0x9a, 0xc9, 0x09, 0x78, 0x65,
+ 0x2f, 0x8a, 0x05, 0x21, 0x0f, 0xe1, 0x24, 0x12, 0xf0, 0x82, 0x45, 0x35, 0x93, 0xda, 0x8e, 0x96,
+ 0x8f, 0xdb, 0xbd, 0x36, 0xd0, 0xce, 0x94, 0x13, 0x5c, 0xd2, 0xf1, 0x40, 0x46, 0x83, 0x38, 0x66,
+ 0xdd, 0xfd, 0x30, 0xbf, 0x06, 0x8b, 0x62, 0xb3, 0x25, 0xe2, 0x98, 0x22, 0x88, 0x91, 0x10, 0x7e,
+ 0x6e, 0x48, 0xc3, 0xa3, 0xb6, 0x1e, 0x42, 0x3a, 0x6b, 0x28, 0x54, 0xfa, 0x85, 0x3d, 0xba, 0x2b,
+ 0x79, 0x0a, 0x15, 0x9b, 0x9f, 0x5e, 0xca, 0x4e, 0xd4, 0xac, 0xe5, 0xf3, 0x73, 0xa7, 0x57, 0xaf,
+ 0x58, 0xa8, 0x50, 0xf4, 0xea, 0xd6, 0x74, 0x4f, 0xae, 0xe9, 0xd5, 0xe7, 0xe6, 0xad, 0xe8, 0x2c,
+ 0xd7, 0x75, 0x7a, 0xeb, 0x16, 0x0b, 0xf5, 0x59, 0xcb, 0x5f, 0xb0, 0x9c, 0xa9, 0x51, 0xa0, 0x7f,
+ 0x0c, 0xf6, 0x6f, 0x17, 0xc4, 0x49, 0xec, 0xd8, 0x43, 0x1f, 0x2d, 0xa4, 0x76, 0x7b, 0xb7, 0xcc,
+ 0xbb, 0x3e, 0x5a, 0xfb, 0x60, 0xb1, 0x86, 0x3b, 0x52, 0xa1, 0x6c, 0xaa, 0x55, 0x29, 0x9d, 0x97,
+ 0xb2, 0x87, 0x90, 0x61, 0xbe, 0xdc, 0xfc, 0xbc, 0x95, 0xcf, 0xcd, 0x37, 0x3f, 0x5b, 0xd1, 0x53,
+ 0x39, 0x84, 0x3c, 0x41, 0xa2, 0x6d, 0x47, 0x14, 0x2a, 0x9e, 0x5d, 0x56, 0xf2, 0xd3, 0xab, 0x44,
+ 0x11, 0x92, 0xd9, 0x23, 0x20, 0x2e, 0x89, 0xb4, 0x7c, 0xb8, 0x26, 0x77, 0x99, 0xe3, 0xa5, 0x67,
+ 0x4a, 0xed, 0xde, 0xc5, 0x31, 0xfe, 0x18, 0x0d, 0x63, 0x8c, 0x80, 0xc0, 0xf7, 0x70, 0x07};
+
+// We disable lots of optimizations that result in non-constant runtime (+/- branch delays)
+static uint8_t field_mul_ret(uint8_t calc, uint8_t a, uint8_t b) __attribute__((optimize("-O0"))) noinline;
+static uint8_t field_mul_ret(uint8_t calc, uint8_t a, uint8_t b) {
+ uint8_t ret, ret2;
+ if (a == 0)
+ ret2 = 0;
+ else
+ ret2 = calc;
+ if (b == 0)
+ ret = 0;
+ else
+ ret = ret2;
return ret;
}
-
-static uint8_t field_neg(uint8_t a) {
- assert(a < p);
- if (a == 0)
- return 0;
- return p - a;
+static uint8_t field_mul(uint8_t a, uint8_t b) {
+ return field_mul_ret(exp[(log[a] + log[b]) % 255], a, b);
}
static uint8_t field_invert(uint8_t a) {
- // Brute force, yay!
- assert(a < p);
- for (uint8_t i = 0; i < p; i++) {
- if (field_mul(i, a) == 1)
- return i;
- }
- assert(0);
-}*/
-
-
-
-/*
- * Calculations across the finite field GF(2^8)
- */
-const uint16_t p = 256;
-static uint8_t field_add(uint8_t a, uint8_t b) {
- return a ^ b;
+ CHECKSTATE(a != 0);
+ return exp[0xff - log[a]]; // log[1] == 0xff
}
-static uint8_t field_sub(uint8_t a, uint8_t b) {
- return a ^ b;
+// We disable lots of optimizations that result in non-constant runtime (+/- branch delays)
+static uint8_t field_pow_ret(uint8_t calc, uint8_t a, uint8_t e) __attribute__((optimize("-O0"))) noinline;
+static uint8_t field_pow_ret(uint8_t calc, uint8_t a, uint8_t e) {
+ uint8_t ret, ret2;
+ if (a == 0)
+ ret2 = 0;
+ else
+ ret2 = calc;
+ if (e == 0)
+ ret = 1;
+ else
+ ret = ret2;
+ return ret;
+}
+static uint8_t field_pow(uint8_t a, uint8_t e) {
+#ifndef TEST
+ // Although this function works for a==0, its not trivially obvious why,
+ // and since we never call with a==0, we just assert a != 0 (except when testing)
+ CHECKSTATE(a != 0);
+#endif
+ return field_pow_ret(exp[(log[a] * e) % 255], a, e);
}
-static uint8_t field_mul(uint8_t a, uint8_t b) {
- // TODO side-channel attacks here?
+#ifdef TEST
+static uint8_t field_mul_calc(uint8_t a, uint8_t b) {
+ // side-channel attacks here
uint8_t ret = 0;
uint8_t counter;
uint8_t carry;
carry = (a & 0x80);
a <<= 1;
if (carry)
- a ^= 0x1b; /* what x^8 is modulo x^8 + x^4 + x^3 + x + 1 */
+ a ^= 0x1b; // what x^8 is modulo x^8 + x^4 + x^3 + x + 1
b >>= 1;
}
return ret;
}
-
-// WARNING: Do not use if e is secret (potential side-channel attacks)
-static uint8_t field_pow(uint8_t a, uint8_t e) {
- // TODO: This could be sped up pretty trivially
+static uint8_t field_pow_calc(uint8_t a, uint8_t e) {
uint8_t ret = 1;
for (uint8_t i = 0; i < e; i++)
- ret = field_mul(ret, a);
+ ret = field_mul_calc(ret, a);
return ret;
}
+int main() {
+ // Test inversion with the logarithm tables
+ for (uint16_t i = 1; i < P; i++)
+ CHECKSTATE(field_mul_calc(i, field_invert(i)) == 1);
+
+ // Test multiplication with the logarithm tables
+ for (uint16_t i = 0; i < P; i++) {
+ for (uint16_t j = 0; j < P; j++)
+ CHECKSTATE(field_mul(i, j) == field_mul_calc(i, j));
+ }
-static uint8_t field_neg(uint8_t a) {
- return field_sub(0, a);
-}
-
-static const uint8_t inverse[] = { // Multiplicative inverse of each element in the field
- 0xff, // 0 has no inverse
- 0x01, 0x8d, 0xf6, 0xcb, 0x52, 0x7b, 0xd1, 0xe8, 0x4f, 0x29, 0xc0, 0xb0, 0xe1, 0xe5, 0xc7, 0x74,
- 0xb4, 0xaa, 0x4b, 0x99, 0x2b, 0x60, 0x5f, 0x58, 0x3f, 0xfd, 0xcc, 0xff, 0x40, 0xee, 0xb2, 0x3a,
- 0x6e, 0x5a, 0xf1, 0x55, 0x4d, 0xa8, 0xc9, 0xc1, 0x0a, 0x98, 0x15, 0x30, 0x44, 0xa2, 0xc2, 0x2c,
- 0x45, 0x92, 0x6c, 0xf3, 0x39, 0x66, 0x42, 0xf2, 0x35, 0x20, 0x6f, 0x77, 0xbb, 0x59, 0x19, 0x1d,
- 0xfe, 0x37, 0x67, 0x2d, 0x31, 0xf5, 0x69, 0xa7, 0x64, 0xab, 0x13, 0x54, 0x25, 0xe9, 0x09, 0xed,
- 0x5c, 0x05, 0xca, 0x4c, 0x24, 0x87, 0xbf, 0x18, 0x3e, 0x22, 0xf0, 0x51, 0xec, 0x61, 0x17, 0x16,
- 0x5e, 0xaf, 0xd3, 0x49, 0xa6, 0x36, 0x43, 0xf4, 0x47, 0x91, 0xdf, 0x33, 0x93, 0x21, 0x3b, 0x79,
- 0xb7, 0x97, 0x85, 0x10, 0xb5, 0xba, 0x3c, 0xb6, 0x70, 0xd0, 0x06, 0xa1, 0xfa, 0x81, 0x82, 0x83,
- 0x7e, 0x7f, 0x80, 0x96, 0x73, 0xbe, 0x56, 0x9b, 0x9e, 0x95, 0xd9, 0xf7, 0x02, 0xb9, 0xa4, 0xde,
- 0x6a, 0x32, 0x6d, 0xd8, 0x8a, 0x84, 0x72, 0x2a, 0x14, 0x9f, 0x88, 0xf9, 0xdc, 0x89, 0x9a, 0xfb,
- 0x7c, 0x2e, 0xc3, 0x8f, 0xb8, 0x65, 0x48, 0x26, 0xc8, 0x12, 0x4a, 0xce, 0xe7, 0xd2, 0x62, 0x0c,
- 0xe0, 0x1f, 0xef, 0x11, 0x75, 0x78, 0x71, 0xa5, 0x8e, 0x76, 0x3d, 0xbd, 0xbc, 0x86, 0x57, 0x0b,
- 0x28, 0x2f, 0xa3, 0xda, 0xd4, 0xe4, 0x0f, 0xa9, 0x27, 0x53, 0x04, 0x1b, 0xfc, 0xac, 0xe6, 0x7a,
- 0x07, 0xae, 0x63, 0xc5, 0xdb, 0xe2, 0xea, 0x94, 0x8b, 0xc4, 0xd5, 0x9d, 0xf8, 0x90, 0x6b, 0xb1,
- 0x0d, 0xd6, 0xeb, 0xc6, 0x0e, 0xcf, 0xad, 0x08, 0x4e, 0xd7, 0xe3, 0x5d, 0x50, 0x1e, 0xb3, 0x5b,
- 0x23, 0x38, 0x34, 0x68, 0x46, 0x03, 0x8c, 0xdd, 0x9c, 0x7d, 0xa0, 0xcd, 0x1a, 0x41, 0x1c};
-static uint8_t field_invert(uint8_t a) {
- assert(a != 0);
- return inverse[a];
+ // Test exponentiation with the logarithm tables
+ for (uint16_t i = 0; i < P; i++) {
+ for (uint16_t j = 0; j < P; j++)
+ CHECKSTATE(field_pow(i, j) == field_pow_calc(i, j));
+ }
}
+#endif // defined(TEST)
/*
* Calculations across the polynomial q
*/
-static uint8_t calculateQ(uint8_t a[], uint8_t k, uint8_t x) {
- assert(x != 0); // q(0) == secret, though so does a[0]
- uint8_t ret = a[0];
- for (uint8_t i = 1; i < k; i++) {
- ret = field_add(ret, field_mul(a[i], field_pow(x, i)));
+#ifndef TEST
+/**
+ * Calculates the Y coordinate that the point with the given X
+ * coefficients[0] == secret, the rest are random values
+ */
+uint8_t calculateQ(uint8_t coefficients[], uint8_t shares_required, uint8_t x) {
+ uint8_t ret = coefficients[0], i;
+ CHECKSTATE(x != 0); // q(0) == secret, though so does a[0]
+ for (i = 1; i < shares_required; i++) {
+ ret = field_add(ret, field_mul(coefficients[i], field_pow(x, i)));
}
return ret;
}
-uint8_t calculateSecret(uint8_t x[], uint8_t q[], uint8_t k) {
+/**
+ * Derives the secret given a set of shares_required points (x and q coordinates)
+ */
+uint8_t calculateSecret(uint8_t x[], uint8_t q[], uint8_t shares_required) {
// Calculate the x^0 term using a derivation of the forumula at
// http://en.wikipedia.org/wiki/Lagrange_polynomial#Example_2
- uint8_t ret = 0;
- for (uint8_t i = 0; i < k; i++) {
+ uint8_t ret = 0, i, j;
+ for (i = 0; i < shares_required; i++) {
uint8_t temp = q[i];
- for (uint8_t j = 0; j < k; j++) {
+ for (j = 0; j < shares_required; j++) {
if (i == j)
continue;
temp = field_mul(temp, field_neg(x[j]));
}
return ret;
}
-
-#define ERROREXIT(str...) {fprintf(stderr, str); exit(1);}
-
-int main(int argc, char* argv[]) {
- assert(mlockall(MCL_CURRENT | MCL_FUTURE) == 0);
-
- char split = 0;
- uint8_t n = 0, k = 0;
- char* files[p]; uint8_t files_count = 0;
- char *in_file = (void*)0, *out_file_param = (void*)0;
-
- int i;
- while((i = getopt(argc, argv, "scn:k:f:o:i:h?")) != -1)
- switch(i) {
- case 's':
- if ((split & 0x2) && !(split & 0x1))
- ERROREXIT("-s (split) and -c (combine) are mutually exclusive\n")
- else
- split = (0x2 | 0x1);
- break;
- case 'c':
- if ((split & 0x2) && (split & 0x1))
- ERROREXIT("-s (split) and -c (combine) are mutually exclusive\n")
- else
- split = 0x2;
- break;
- case 'n': {
- int t = atoi(optarg);
- if (t <= 0 || t >= p)
- ERROREXIT("n must be > 0 and < %u\n", p)
- else
- n = t;
- break;
- }
- case 'k': {
- int t = atoi(optarg);
- if (t <= 0 || t >= p)
- ERROREXIT("n must be > 0 and < %u\n", p)
- else
- k = t;
- break;
- }
- case 'i':
- in_file = optarg;
- break;
- case 'o':
- out_file_param = optarg;
- break;
- case 'f':
- if (files_count >= p-1)
- ERROREXIT("May only specify up to %u files\n", p-1)
- files[files_count++] = optarg;
- break;
- case 'h':
- case '?':
- printf("Split usage: -s -n <total shares> -k <shares required> -i <input file> -o <output file path base>\n");
- printf("Combine usage: -c -k <shares provided == shares required> <-f <share>>*k -o <output file>\n");
- exit(0);
- break;
- default:
- ERROREXIT("getopt failed?\n")
- }
- if (!(split & 0x2))
- ERROREXIT("Must specify either -c or -s\n")
- split &= 0x1;
-
- if (argc != optind)
- ERROREXIT("Invalid argument\n")
-
- if (split) {
- if (!n || !k)
- ERROREXIT("n and k must be set.\n")
-
- if (k > n)
- ERROREXIT("k must be <= n\n")
-
- if (files_count != 0 || !in_file || !out_file_param)
- ERROREXIT("Must specify -i <input file> and -o <output file path base> but not -f in split mode.\n")
-
- FILE* random = fopen("/dev/random", "r");
- assert(random);
- FILE* secret_file = fopen(in_file, "r");
- if (!secret_file)
- ERROREXIT("Could not open %s for reading.\n", in_file)
-
- uint8_t secret[MAX_LENGTH];
- memset(secret, 0, MAX_LENGTH*sizeof(uint8_t));
-
- size_t secret_length = fread(secret, 1, MAX_LENGTH*sizeof(uint8_t), secret_file);
- if (secret_length == 0)
- ERROREXIT("Error reading secret\n")
- if (fread(secret, 1, 1, secret_file) > 0)
- ERROREXIT("Secret may not be longer than %u\n", MAX_LENGTH)
- fclose(secret_file);
- printf("Using secret of length %lu\n", secret_length);
-
- uint8_t a[secret_length][k], D[n][secret_length];
-
- for (uint8_t i = 0; i < secret_length; i++) {
- a[i][0] = secret[i];
-
- for (uint8_t j = 1; j < k; j++) {
- do
- assert(fread(&a[i][j], sizeof(uint8_t), 1, random) == 1);
- while (a[i][j] >= p);
- }
- for (uint8_t j = 0; j < n; j++)
- D[j][i] = calculateQ(a[i], k, j+1);
- }
-
- char out_file_name_buf[strlen(out_file_param) + 4];
- strcpy(out_file_name_buf, out_file_param);
- for (uint8_t i = 0; i < n; i++) {
- /*printf("%u-", i);
- for (uint8_t j = 0; j < secret_length; j++)
- printf("%02x", D[i][j]);
- printf("\n");*/
-
- sprintf(((char*)out_file_name_buf) + strlen(out_file_param), "%u", i);
- FILE* out_file = fopen(out_file_name_buf, "w+");
- if (!out_file)
- ERROREXIT("Could not open output file %s\n", out_file_name_buf)
-
- uint8_t x = i+1;
- if (fwrite(&x, sizeof(uint8_t), 1, out_file) != 1)
- ERROREXIT("Could not write 1 byte to %s\n", out_file_name_buf)
-
- if (fwrite(D[i], 1, secret_length, out_file) != secret_length)
- ERROREXIT("Could not write %lu bytes to %s\n", secret_length, out_file_name_buf)
-
- fclose(out_file);
- }
- /*printf("secret = ");
- for (uint8_t i = 0; i < secret_length; i++)
- printf("%02x", secret[i]);
- printf("\n");*/
-
- fclose(random);
- } else {
- if (!k)
- ERROREXIT("k must be set.\n")
-
- if (files_count != k || in_file || !out_file_param)
- ERROREXIT("Must not specify -i and must specify -o and exactly k -f <input file>s in combine mode.\n")
-
- uint8_t x[k], q[k];
- FILE* files_fps[k];
-
- for (uint8_t i = 0; i < k; i++) {
- files_fps[i] = fopen(files[i], "r");
- if (!files_fps[i])
- ERROREXIT("Couldn't open file %s for reading.\n", files[i])
- if (fread(&x[i], sizeof(uint8_t), 1, files_fps[i]) != 1)
- ERROREXIT("Couldn't read the x byte of %s\n", files[i])
- }
-
- uint8_t secret[MAX_LENGTH];
-
- uint8_t i = 0;
- while (fread(&q[0], sizeof(uint8_t), 1, files_fps[0]) == 1) {
- for (uint8_t j = 1; j < k; j++) {
- if (fread(&q[j], sizeof(uint8_t), 1, files_fps[j]) != 1)
- ERROREXIT("Couldn't read next byte from %s\n", files[j])
- }
- secret[i++] = calculateSecret(x, q, k);
- }
- printf("Got secret of length %u\n", i);
-
- FILE* out_file = fopen(out_file_param, "w+");
- fwrite(secret, sizeof(uint8_t), i, out_file);
- fclose(out_file);
-
- for (uint8_t i = 0; i < k; i++)
- fclose(files_fps[i]);
- }
-
- return 0;
-}
+#endif // !defined(TEST)
projects / shamirs / blobdiff