--- /dev/null
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <stdbool.h>
+#include <assert.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+#include "shamirssecret.h"
+
+#define MAX_LENGTH 1024
+#define ERROREXIT(str...) {fprintf(stderr, str); exit(1);}
+
+#ifndef TEST
+static void derive_missing_part(uint8_t total_shares, uint8_t shares_required, bool parts_have[], uint8_t* split_version, uint8_t split_index, uint8_t split_size) {
+ uint8_t (*D)[split_size] = (uint8_t (*)[split_size])split_version;
+ uint8_t x[shares_required], q[shares_required];
+
+ // Fill in x/q with the selected shares
+ uint16_t x_pos = 0;
+ for (uint8_t i = 0; i < P-1; i++) {
+ if (parts_have[i]) {
+ x[x_pos] = i+1;
+ q[x_pos++] = D[i][split_index];
+ }
+ }
+ assert(x_pos == shares_required - 1);
+
+ // Now loop through ALL x we didn't already set (despite not having that many
+ // shares, because more shares could be added arbitrarily, any x should not be
+ // able to rule out any possible secrets) and try each possible q, making sure
+ // that each q gives us a new possibility for the secret.
+ bool impossible_secrets[P];
+ memset(impossible_secrets, 0, sizeof(impossible_secrets));
+ for (uint16_t final_x = 1; final_x < P; final_x++) {
+ bool x_already_used = false;
+ for (uint8_t j = 0; j < shares_required; j++) {
+ if (x[j] == final_x)
+ x_already_used = true;
+ }
+ if (x_already_used)
+ continue;
+
+ x[shares_required-1] = final_x;
+ bool possible_secrets[P];
+ memset(possible_secrets, 0, sizeof(possible_secrets));
+ for (uint16_t new_q = 0; new_q < P; new_q++) {
+ q[shares_required-1] = new_q;
+ possible_secrets[calculateSecret(x, q, shares_required)] = 1;
+ }
+
+ for (uint16_t i = 0; i < P; i++)
+ assert(possible_secrets[i]);
+ }
+
+ //TODO: Check that gcc isn't optimizing this one away
+ memset(q, 0, sizeof(q));
+}
+
+static void check_possible_missing_part_derivations_intern(uint8_t total_shares, uint8_t shares_required, bool parts_have[], uint8_t parts_included, uint16_t progress, uint8_t* split_version, uint8_t split_index, uint8_t split_size) {
+ if (parts_included == shares_required-1)
+ return derive_missing_part(total_shares, shares_required, parts_have, split_version, split_index, split_size);
+
+ if (total_shares - progress < shares_required)
+ return;
+
+ check_possible_missing_part_derivations_intern(total_shares, shares_required, parts_have, parts_included, progress+1, split_version, split_index, split_size);
+ parts_have[progress] = 1;
+ check_possible_missing_part_derivations_intern(total_shares, shares_required, parts_have, parts_included+1, progress+1, split_version, split_index, split_size);
+ parts_have[progress] = 0;
+}
+
+static void check_possible_missing_part_derivations(uint8_t total_shares, uint8_t shares_required, uint8_t* split_version, uint8_t split_index, uint8_t split_size) {
+ bool parts_have[P];
+ memset(parts_have, 0, sizeof(parts_have));
+ check_possible_missing_part_derivations_intern(total_shares, shares_required, parts_have, 0, 0, split_version, split_index, split_size);
+}
+
+
+int main(int argc, char* argv[]) {
+ assert(mlockall(MCL_CURRENT | MCL_FUTURE) == 0);
+
+ char split = 0;
+ uint8_t total_shares = 0, shares_required = 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
+ total_shares = t;
+ break;
+ }
+ case 'k': {
+ int t = atoi(optarg);
+ if (t <= 0 || t >= P)
+ ERROREXIT("n must be > 0 and < %u\n", P)
+ else
+ shares_required = 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 one of -c, -s or -?\n")
+ split &= 0x1;
+
+ if (argc != optind)
+ ERROREXIT("Invalid argument\n")
+
+ if (split) {
+ if (!total_shares || !shares_required)
+ ERROREXIT("n and k must be set.\n")
+
+ if (shares_required > total_shares)
+ 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];
+
+ 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[shares_required], D[total_shares][secret_length];
+
+ for (uint32_t i = 0; i < secret_length; i++) {
+ a[0] = secret[i];
+
+ for (uint8_t j = 1; j < shares_required; j++)
+ assert(fread(&a[j], sizeof(uint8_t), 1, random) == 1);
+ for (uint8_t j = 0; j < total_shares; j++)
+ D[j][i] = calculateQ(a, shares_required, j+1);
+
+ // Now, for paranoia's sake, we ensure that no matter which piece we are missing, we can derive no information about the secret
+ check_possible_missing_part_derivations(total_shares, shares_required, &(D[0][0]), i, secret_length);
+
+ if (i % 32 == 0 && i != 0)
+ printf("Finished processing %u bytes.\n", i);
+ }
+
+ char out_file_name_buf[strlen(out_file_param) + 4];
+ strcpy(out_file_name_buf, out_file_param);
+ for (uint8_t i = 0; i < total_shares; 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");*/
+
+ // Clear sensitive data (No, GCC 4.7.2 is currently not optimizing this out)
+ memset(secret, 0, sizeof(uint8_t)*secret_length);
+ memset(a, 0, sizeof(uint8_t)*shares_required);
+ memset(in_file, 0, strlen(in_file));
+
+ fclose(random);
+ } else {
+ if (!shares_required)
+ ERROREXIT("k must be set.\n")
+
+ if (files_count != shares_required || 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[shares_required], q[shares_required];
+ FILE* files_fps[shares_required];
+
+ for (uint8_t i = 0; i < shares_required; 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];
+
+ uint32_t i = 0;
+ while (fread(&q[0], sizeof(uint8_t), 1, files_fps[0]) == 1) {
+ for (uint8_t j = 1; j < shares_required; 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, shares_required);
+ }
+ 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 < shares_required; i++)
+ fclose(files_fps[i]);
+
+ // Clear sensitive data (No, GCC 4.7.2 is currently not optimizing this out)
+ memset(secret, 0, sizeof(uint8_t)*i);
+ memset(q, 0, sizeof(uint8_t)*shares_required);
+ memset(out_file_param, 0, strlen(out_file_param));
+ for (uint8_t i = 0; i < shares_required; i++)
+ memset(files[i], 0, strlen(files[i]));
+ memset(x, 0, sizeof(uint8_t)*shares_required);
+ }
+
+ return 0;
+}
+#endif // !defined(TEST)
projects / shamirs / blobdiff