From 9db81cb91674d45bbb4936a098f4e4fb1a5b45bd Mon Sep 17 00:00:00 2001
From: Benedict <benedict@0xb8000.de>
Date: Fri, 4 Mar 2016 12:42:08 +0100
Subject: reimplemented task2

---
 Makefile |  3 +++
 lib.c    | 20 +++++++++++++++-----
 lib.h    |  2 +-
 task2.c  | 27 +++++++++++++++++++++++++++
 test.sh  |  9 +++++++++
 5 files changed, 55 insertions(+), 6 deletions(-)
 create mode 100644 task2.c

diff --git a/Makefile b/Makefile
index 2178244..69b8615 100644
--- a/Makefile
+++ b/Makefile
@@ -6,6 +6,9 @@ all: task1 task4 task5 task6
 task1:
 	$(CC) task1.c $(LIB) -o task1
 
+task2:
+	$(CC) task2.c $(LIB) -o task2
+
 task4:
 	$(CC) task4.c $(LIB) -o task4
 
diff --git a/lib.c b/lib.c
index 4d0d769..252deb2 100644
--- a/lib.c
+++ b/lib.c
@@ -90,7 +90,7 @@ static void three_bytes_to_base64(char * encode, int bytes_to_print, char *resul
  * Transform four base64 encoded characters back to three bytes
  */
 
-void decode_base64(char *string1, char *result)
+void decode_four_base64_byte(char *string1, char *result)
 {
 	char one, two, three, tmp;
 	// first byte is first six bits of base64 one and 2 bit of base64 second
@@ -113,6 +113,16 @@ void decode_base64(char *string1, char *result)
 	printf("%c%c%c", one, two, three);
 }
 
+void decode_base64(char *string1, char *result)
+{
+	int i;
+
+	for(i=0;i<strlen(string1)-3;i++) {
+		decode_four_base64_byte(&string1[i*4], &result[i*3]);
+	}
+	// TODO handle = in base64 at the end
+}
+
 static char string_to_hex_map[] = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06,
 				   0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D,
 				   0x0E, 0x0F};
@@ -203,12 +213,12 @@ static void two_char_hex(char *start, char *result)
  * @param key 
  * @param result buffer where the result is stored
  */
-void xor_string(char *str1, char *key, char *result)
+void xor_string(char *str1, char *key, char *result, int length_key, int length_str1)
 {
 	int i, j;
-	int length_key = strlen(key);
+	//int length_key = strlen(key);
 
-	for(i=0, j=0;i<strlen(str1);i++,j++) {
+	for(i=0, j=0;i<length_str1;i++,j++) {
 		if (j >= length_key)
 			j = 0;
 
@@ -364,7 +374,7 @@ int brute_force_single_byte_xor(char *string, int length, char* keys)
 
 	for(i=1;i<255;i++) {
 		single_byte_key = (char) i;
-		xor_string(string, &single_byte_key, xor_tmp);
+		xor_string(string, &single_byte_key, xor_tmp, 1, length);
 		if (string_looks_like_it_is_human_language(xor_tmp, length)) {
 			keys[number_found_keys++] = single_byte_key;
 			printf("%s\n", xor_tmp);
diff --git a/lib.h b/lib.h
index b8d50d0..a0986e7 100644
--- a/lib.h
+++ b/lib.h
@@ -8,7 +8,7 @@
 #include <ctype.h>
 
 
-void xor_string(char *str1, char *key, char *result);
+void xor_string(char *str1, char *key, char *result, int length_key, int length_str1);
 void hex_binary_to_string(char *str1, char *result, int length);
 int decode_hex_string(char *encode, char* result);
 int encode_to_base64(char *encode, char *result);
diff --git a/task2.c b/task2.c
new file mode 100644
index 0000000..b675244
--- /dev/null
+++ b/task2.c
@@ -0,0 +1,27 @@
+#include "lib.h"
+
+
+int main(int argc, char**argv)
+{
+	if (argc != 3)
+		return 1;
+	
+
+	char *xor_string_tmp = malloc(strlen(argv[1]));
+	char *result = malloc(strlen(argv[1]));
+	char *str1 = malloc(strlen(argv[1]));
+	char *str2 = malloc(strlen(argv[2]));
+
+	decode_hex_string(argv[1], str1);
+	decode_hex_string(argv[2], str2);
+	xor_string(str1, str2, xor_string_tmp, strlen(argv[2]), strlen(argv[1]));
+	hex_binary_to_string(xor_string_tmp, result, strlen(argv[1]));
+	printf("%s\n", result);
+
+	free(xor_string_tmp);
+	free(result);
+	free(str1);
+	free(str2);
+
+	return 0;
+}
diff --git a/test.sh b/test.sh
index a728fa0..780a12b 100644
--- a/test.sh
+++ b/test.sh
@@ -28,5 +28,14 @@ EXCEPTED="SSdtIGtpbGxpbmcgeW91ciBicmFpbiBsaWtlIGEgcG9pc29ub3VzIG11c2hyb29t"
 test_compare_string "$OUTPUT" "$EXCEPTED"
 }
 
+test_set1_challenge2() {
+	echo "test: set1, challenge 2:"
+	OUTPUT=$(./task2 1c0111001f010100061a024b53535009181c 686974207468652062756c6c277320657965)
+	EXCEPTED="746865206b696420646f6e277420706c6179"
+	
+	test_compare_string "$OUTPUT" "$EXCEPTED"
+}
+
 test_set1_challenge1
+test_set1_challenge2
 test_set1_challenge5
-- 
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