s/k/shares_required/

[shamirs] / shamirssecret.c

diff --git a/shamirssecret.c b/shamirssecret.c
index cc3e71334a1277367c2beae82bd05f9496945287..80f835c46318bb2ab825a40135af853d51b96821 100644 (file)
--- a/shamirssecret.c
+++ b/shamirssecret.c
@@ -102,6 +102,11 @@ static uint8_t field_pow_ret(uint8_t calc, uint8_t a, uint8_t e) {
        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)
+       assert(a != 0);
+#endif
        return field_pow_ret(exp[(log[a] * e) % 255], a, e);
 }
 
@@ -185,7 +190,7 @@ int main(int argc, char* argv[]) {
        assert(mlockall(MCL_CURRENT | MCL_FUTURE) == 0);
 
        char split = 0;
-       uint8_t n = 0, k = 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;
 
@@ -209,7 +214,7 @@ int main(int argc, char* argv[]) {
                        if (t <= 0 || t >= P)
                                ERROREXIT("n must be > 0 and < %u\n", P)
                        else
-                               n = t;
+                               total_shares = t;
                        break;
                }
                case 'k': {
@@ -217,7 +222,7 @@ int main(int argc, char* argv[]) {
                        if (t <= 0 || t >= P)
                                ERROREXIT("n must be > 0 and < %u\n", P)
                        else
-                               k = t;
+                               shares_required = t;
                        break;
                }
                case 'i':
@@ -248,10 +253,10 @@ int main(int argc, char* argv[]) {
                ERROREXIT("Invalid argument\n")
 
        if (split) {
-               if (!n || !k)
+               if (!total_shares || !shares_required)
                        ERROREXIT("n and k must be set.\n")
 
-               if (k > n)
+               if (shares_required > total_shares)
                        ERROREXIT("k must be <= n\n")
 
                if (files_count != 0 || !in_file || !out_file_param)
@@ -273,15 +278,15 @@ int main(int argc, char* argv[]) {
                fclose(secret_file);
                printf("Using secret of length %lu\n", secret_length);
 
-               uint8_t a[k], D[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 < k; j++)
+                       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 < n; j++)
-                               D[j][i] = calculateQ(a, k, j+1);
+                       for (uint8_t j = 0; j < total_shares; j++)
+                               D[j][i] = calculateQ(a, shares_required, j+1);
 
                        if (i % 32 == 0 && i != 0)
                                printf("Finished processing %u bytes.\n", i);
@@ -289,7 +294,7 @@ int main(int argc, char* argv[]) {
 
                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++) {
+               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]);
@@ -316,21 +321,21 @@ int main(int argc, char* argv[]) {
 
                // 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)*k);
+               memset(a, 0, sizeof(uint8_t)*shares_required);
                memset(in_file, 0, strlen(in_file));
 
                fclose(random);
        } else {
-               if (!k)
+               if (!shares_required)
                        ERROREXIT("k must be set.\n")
 
-               if (files_count != k || in_file || !out_file_param)
+               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[k], q[k];
-               FILE* files_fps[k];
+               uint8_t x[shares_required], q[shares_required];
+               FILE* files_fps[shares_required];
 
-               for (uint8_t i = 0; i < k; i++) {
+               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])
@@ -342,11 +347,11 @@ int main(int argc, char* argv[]) {
 
                uint32_t i = 0;
                while (fread(&q[0], sizeof(uint8_t), 1, files_fps[0]) == 1) {
-                       for (uint8_t j = 1; j < k; j++) {
+                       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, k);
+                       secret[i++] = calculateSecret(x, q, shares_required);
                }
                printf("Got secret of length %u\n", i);
 
@@ -354,16 +359,16 @@ int main(int argc, char* argv[]) {
                fwrite(secret, sizeof(uint8_t), i, out_file);
                fclose(out_file);
 
-               for (uint8_t i = 0; i < k; i++)
+               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)*k);
+               memset(q, 0, sizeof(uint8_t)*shares_required);
                memset(out_file_param, 0, strlen(out_file_param));
-               for (uint8_t i = 0; i < k; i++)
+               for (uint8_t i = 0; i < shares_required; i++)
                        memset(files[i], 0, strlen(files[i]));
-               memset(x, 0, sizeof(uint8_t)*k);
+               memset(x, 0, sizeof(uint8_t)*shares_required);
        }
 
        return 0;