set1, challenge 8 completed

1 files changed, 55 insertions, 0 deletions

diff --git a/set1/task8.c b/set1/task8.c
new file mode 100644
index 0000000..98b3380
--- /dev/null
+++ b/set1/task8.c
@@ -0,0 +1,55 @@
+#include "../lib/lib.h"
+
+
+int main(int arc, char **argv)
+{
+	// detect AEC in ECB mode, do NOT break it
+	int number_blocks, i, j, k, read = 0;
+	size_t len = 0;
+	int max_hits = 0, hits = 0, line_number= 0, aes_ecb_line = 0;
+	char *line_hex = NULL;
+	// read file
+	FILE *f = fopen("8.txt", "r");
+
+	if (f == NULL) {
+		perror("failed to open 8.txt");
+		exit(1);
+	}
+
+	while( (read = getline(&line_hex, &len, f)) != -1) {
+		// line is hex encoded 
+		char *line = malloc(read/2+1);
+
+		decode_hex_string(line_hex, line);
+
+		number_blocks = read / 2 / 16;
+		// count 16 byte blocks which are equal
+		for(i=0;i<number_blocks;i++) {
+			for(j=1;j<number_blocks;j++) {
+				for(k=0;k<16;k++) {
+					if(line[i*16+k] != line[j*16+k])
+						break;
+
+					if ( k == 15)
+						hits++;
+				}
+			}
+		}
+		printf("line: %i, hits: %i\n", line_number, hits);
+		if (hits > max_hits) {
+			max_hits = hits;
+			aes_ecb_line = line_number;
+		}
+		line_number++;
+		hits = 0;
+		free(line_hex);
+		free(line);
+		// set line and len to null
+		line = NULL;
+		len = 0;
+	}
+
+	printf("found AES-128-ECB at line: %i\n with %i hits", aes_ecb_line, max_hits);
+
+	return 0;
+}