X-Git-Url: http://git.bitcoin.ninja/index.cgi?p=shamirs;a=blobdiff_plain;f=main.c;fp=main.c;h=8301c0b9616ab56bce515bee85fdaa483ddb6420;hp=0000000000000000000000000000000000000000;hb=5958ded10d4f4496f34ae8f5aad0b34153ed3dd6;hpb=39318502b0e2fedca71d901ba007fea2a0d26208 diff --git a/main.c b/main.c new file mode 100644 index 0000000..8301c0b --- /dev/null +++ b/main.c @@ -0,0 +1,272 @@ +#define _GNU_SOURCE + +#include +#include +#include +#include +#include +#include +#include + +#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 -k -i -o \n"); + printf("Combine usage: -c -k <-f >*k -o \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 and -o 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 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)