From 2f6023b20f70885b874bf78c4c07046b30c479ab Mon Sep 17 00:00:00 2001
From: Benedict <benedict@0xb8000.de>
Date: Thu, 18 Aug 2016 23:20:46 +0200
Subject: set4, completed challenge 26

---
 set4/task26.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 set4/task26.c

(limited to 'set4/task26.c')

diff --git a/set4/task26.c b/set4/task26.c
new file mode 100644
index 0000000..5c7b047
--- /dev/null
+++ b/set4/task26.c
@@ -0,0 +1,32 @@
+#include "../lib/lib.h"
+#include "../lib/lib2.h"
+#include "../lib/lib3.h"
+#include "../lib/lib4.h"
+#include <time.h>
+
+
+int main()
+{
+	generate_random_bytes(key, 16);
+	generate_random_bytes(iv, 16);
+
+	char *encrypted;
+	int length_enc = challenge16_encrypt(":admin<true:", &encrypted, 0);
+
+	char *plaintext;
+	printf("the unchanged string:\n%s\n", plaintext);
+	challenge16_decrypt(encrypted, length_enc, 0);
+	/**
+	  * the encrpyt function prepends two blocks
+	  * 
+	  * we need to flip three bits, the 8th bit, 56th bit and the
+	  * 96th bit
+	  */
+	encrypted[32] ^= 0x01;
+	encrypted[38] ^= 0x01;
+	encrypted[43] ^= 0x01;
+
+	printf("now the changed string:\n");
+	challenge16_decrypt(encrypted, length_enc, 0);
+	return 0;
+}
-- 
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