X-Git-Url: http://git.bitcoin.ninja/index.cgi?p=shamirs;a=blobdiff_plain;f=shamirssecret.c;h=be6eed3f9d0c4247dc09a6a7d27fa0f775a32396;hp=b69004884bb889f5f0dc9530d39edd42b76092a8;hb=421e5acbd6f375ca9f2f16d260fe9c5505fb42f4;hpb=b6006436d939a7cba7c141f00b4efc638a694d14

diff --git a/shamirssecret.c b/shamirssecret.c
index b690048..be6eed3 100644
--- 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);
 }
 
@@ -125,7 +130,7 @@ static uint8_t field_mul_calc(uint8_t a, uint8_t b) {
 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() {
@@ -134,7 +139,7 @@ int main() {
 		assert(field_mul_calc(i, field_invert(i)) == 1);
 
 	// Test multiplication with the logarithm tables
-	for (uint16_t i = 0; i < 2; i++) {
+	for (uint16_t i = 0; i < P; i++) {
 		for (uint16_t j = 0; j < P; j++)
 			assert(field_mul(i, j) == field_mul_calc(i, j));
 	}
@@ -241,7 +246,7 @@ int main(int argc, char* argv[]) {
 			ERROREXIT("getopt failed?\n")
 		}
 	if (!(split & 0x2))
-		ERROREXIT("Must specify either -c or -s\n")
+		ERROREXIT("Must specify one of -c, -s or -?\n")
 	split &= 0x1;
 
 	if (argc != optind)
@@ -264,7 +269,6 @@ int main(int argc, char* argv[]) {
 			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)
@@ -274,15 +278,18 @@ int main(int argc, char* argv[]) {
 		fclose(secret_file);
 		printf("Using secret of length %lu\n", secret_length);
 
-		uint8_t a[secret_length][k], D[n][secret_length];
+		uint8_t a[k], D[n][secret_length];
 
-		for (uint8_t i = 0; i < secret_length; i++) {
-			a[i][0] = secret[i];
+		for (uint32_t i = 0; i < secret_length; i++) {
+			a[0] = secret[i];
 
 			for (uint8_t j = 1; j < k; j++)
-				assert(fread(&a[i][j], sizeof(uint8_t), 1, random) == 1);
+				assert(fread(&a[j], sizeof(uint8_t), 1, random) == 1);
 			for (uint8_t j = 0; j < n; j++)
-				D[j][i] = calculateQ(a[i], k, j+1);
+				D[j][i] = calculateQ(a, k, j+1);
+
+			if (i % 32 == 0 && i != 0)
+				printf("Finished processing %u bytes.\n", i);
 		}
 
 		char out_file_name_buf[strlen(out_file_param) + 4];
@@ -312,6 +319,11 @@ int main(int argc, char* argv[]) {
 			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)*k);
+		memset(in_file, 0, strlen(in_file));
+
 		fclose(random);
 	} else {
 		if (!k)
@@ -333,7 +345,7 @@ int main(int argc, char* argv[]) {
 
 		uint8_t secret[MAX_LENGTH];
 
-		uint8_t i = 0;
+		uint32_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)
@@ -349,6 +361,14 @@ int main(int argc, char* argv[]) {
 
 		for (uint8_t i = 0; i < k; 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(out_file_param, 0, strlen(out_file_param));
+		for (uint8_t i = 0; i < k; i++)
+			memset(files[i], 0, strlen(files[i]));
+		memset(x, 0, sizeof(uint8_t)*k);
 	}
 
 	return 0;