M set1/Makefile → set1/Makefile

@@ -5,7 +5,7 @@ DEBUG   = -0g -ggdb
 LINK    = 
 SRC_DIR = src
 OUT_DIR = bin
-TARGETS = base64 fixed-xor
+TARGETS = base64 fixed-xor char-freq-analize
 
 
 all: $(TARGETS)

A set1/src/char-freq-analyze.c

@@ -0,0 +1,28 @@ 
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int main()
+{
+	size_t i;
+	int8_t ciphertext[] = "\x1b\x37\x37\x33\x31\x36\x3f\x78\x15\x1b\x7f\x2b"
+	                      "\x78\x34\x31\x33\x3d\x78\x39\x78\x28\x37\x2d\x36"
+	                      "\x3c\x78\x37\x3e\x78\x3a\x39\x3b\x37\x36";
+	uint8_t byte_freq[256];
+	memset(byte_freq, 0, sizeof(byte_freq));
+
+	// get histogram (count byte occurences)
+	for (i = 0; i < sizeof(ciphertext)-1; ++i) {
+		byte_freq[ciphertext[i]] += 1;
+	}
+
+	for (i = 0; i < sizeof(byte_freq); ++i) {
+		if (byte_freq[i] != 0) {
+			printf("%x occurs %d times\n", i, byte_freq[i]);
+		}
+	}
+
+	return EXIT_SUCCESS;
+}
+