From 723222e769785563babdda5f78a0ce21a276cb9f Mon Sep 17 00:00:00 2001
From: Benedict <benedict@0xb8000.de>
Date: Fri, 23 Sep 2016 11:36:08 +0200
Subject: completed set 4, task 31

---
 lib/lib3.c | 43 ++++++++++++++++++++++++++++++-------------
 1 file changed, 30 insertions(+), 13 deletions(-)

(limited to 'lib/lib3.c')

diff --git a/lib/lib3.c b/lib/lib3.c
index 150c6ea..149d3a3 100644
--- a/lib/lib3.c
+++ b/lib/lib3.c
@@ -8,36 +8,46 @@
 char *challenge17_encrypt(int *length)
 {
 	int i, t;
-	char **string;
-	char **decoded;
-	string = malloc(sizeof(char *)*NR_STIRNGS_CHALLENGE17);
-	decoded = malloc(sizeof(char *)*NR_STIRNGS_CHALLENGE17);
+	char *string[NR_STIRNGS_CHALLENGE17];
+	char *decoded[NR_STIRNGS_CHALLENGE17];
 	char filename[] = "task17_0";	
 
-	for(i=0;i<10;i++) {
+	for(i=0;i<NR_STIRNGS_CHALLENGE17;i++) {
 		filename[strlen(filename)-1] = (char) (i+'0');
 		t = read_base64_file(filename, &string[i]);
 		decoded[i] = malloc(t);
-		length[i] = decode_base64(string[i], decoded[i]);
-		printf("read: %s\n", string[i]);
+		*length = decode_base64(string[i], decoded[i]);
+		printf("read: %s\n", decoded[i]);
 	}
+	
 	// choose one randomly
 	int random = rand() % NR_STIRNGS_CHALLENGE17;
 	int padding;
-	printf("plaintext: %s\n", string[random]);
+
+	//random = 1;
 	*length = strlen(string[random]);
-	char *padded_string = __pkcs7_padding(string[random], *length, 16, &padding);
+	char *padded_string = __pkcs7_padding(decoded[random], *length, 16, &padding);
+	char *hex_tmp = malloc((padding+strlen(decoded[random]))*2);
+	hex_binary_to_string(padded_string, hex_tmp, padding+strlen(decoded[random]));
+	printf("plaintext: %s\n", decoded[random]);
+	printf("plaintext: %s\n", hex_tmp);
 	char *encrypted = malloc(strlen(padded_string));
 	*length += padding;
 	aes_cbc(padded_string, strlen(padded_string), encrypted, key, iv, 1);
+	for(i=0;i<NR_STIRNGS_CHALLENGE17;i++)
+		free(decoded[i]);
 	return encrypted;	
+
 }
 
 int cbc_padding_oracle(char *encrypted, int length)
 {
 	char *decrypted = malloc(length);
 	char *unpadded= malloc(length);
-	
+
+	if(!decrypted || !unpadded)
+		return -1;
+
 	aes_cbc(encrypted, length, decrypted, key, iv, 0);
 
 	int valid = valid_pkcs7_padding(decrypted, length, unpadded, 16);
@@ -184,9 +194,6 @@ int unshift_right_xor(int number, int shifts)
 	return restore;
 }
 
-/***
-  * why the fuck is the reverse AND working?
-  **/
 int unshift_left_xor(int number, int shifts, unsigned int mask)
 {
 	int rounds = 0;
@@ -281,3 +288,13 @@ int mt_19937_password_token_time_based(unsigned int password_token, int time_win
 	}
 	return 0;
 }
+/**
+  * Given the actual state, restore the previous state of the MT
+  * This is useful, when you want to determine the previous random numbers
+  * you may not have observed.
+  *
+  **/
+int mt_19937_restore_previous_state(struct mt_19937_state *mt_state)
+{
+
+}
-- 
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