From e836057207c9de21c5af8f21191aea86184662a3 Mon Sep 17 00:00:00 2001
From: Benedict <benedict@0xb8000.de>
Date: Tue, 1 Mar 2016 23:18:35 +0100
Subject: set 1, challenge 4 completed

---
 task1_hex_to_base64.c | 79 ++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 69 insertions(+), 10 deletions(-)

(limited to 'task1_hex_to_base64.c')

diff --git a/task1_hex_to_base64.c b/task1_hex_to_base64.c
index 40c0a94..c4bf7d9 100644
--- a/task1_hex_to_base64.c
+++ b/task1_hex_to_base64.c
@@ -212,23 +212,81 @@ void hex_binary_to_string(char *str1, char *result, int length)
 
 
 
-int score_based_on_frequent_characters(char *string)
+int score_based_on_frequent_characters(char *string, int length)
 {
 	int number = 0;
 	int i;
-	int length = strlen(string);
 	char tmp;
 
-	for(i=0;i<strlen(string);i++) {
+	for(i=0;i<length;i++) {
 		tmp = tolower(string[i]);	
 		if( tmp == 'e' || tmp == 'a' || tmp == 'i' || tmp == 'o'
 			|| tmp == 'u' )
 			number++;
 	}
 
-	return (number*100/length);
+	return ((number*100)/length);
 }
 
+int isprintable(char *string, int length)
+{
+	int i;
+
+	for(i=0;i<length;i++) {
+		if(!(isprint(string[i]) || isspace(string[i]))) {
+			return 0;
+		}
+	}
+
+	return 1;
+}
+
+void string_looks_like_it_is_english(char *string, int length)
+{
+	char *xor_tmp = malloc(strlen(string));
+	int i;
+
+	for(i= 0; i< 255; i++) {
+		xor_string_single_byte((char) i, string, xor_tmp, length);
+		if (!isprintable(xor_tmp, length))
+			continue;
+		int score = score_based_on_frequent_characters(xor_tmp, length);
+		if(score > 20)
+			printf("char: %c, score: %i, string: %s\n", (char) i, score, xor_tmp);
+	}
+
+	//free(xor_tmp);
+}
+
+void task4() {
+	/** read the file */
+	FILE *fp;
+	int bytes_read;
+	int malloc_size = 62;
+	int line_number = 0;
+	int j;
+	char *string = malloc(malloc_size);
+	char *string2 = malloc(malloc_size);
+
+	fp = fopen("4.txt", "r");
+
+	if (fp == NULL) {
+		printf("Error open file\n");
+		exit(1);
+	}
+	
+	while (fscanf(fp, "%61c", string) != EOF) {
+		j = convert_hex_string_to_character_string(string, string2);
+		printf("line number: %i, length: %i,\n",  line_number, j);
+		string_looks_like_it_is_english(string2, j);
+		line_number++;
+	}
+
+	fclose(fp);
+
+}
+
+
 int main(int argc, char **argv)
 {
 	if (argc == 3 ) {
@@ -265,12 +323,13 @@ int main(int argc, char **argv)
 
 		printf("***************************\n");
 		printf("set 1, challenge 3\n");
-		for(i= 'A'; i< 'Z'; i++) {
-			xor_string_single_byte((char) i, tmp2, __xor_string, j);
-			int score = score_based_on_frequent_characters(__xor_string);
-			if(score > 30)
-				printf("char: %c, score: %i, string: %s\n", (char) i, score, __xor_string);
+		//string_looks_
+
 		}
 
-	}
+	printf("***************************\n");
+	printf("set 1, challenge 4\n");
+	task4();
+
+
 }
-- 
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