set4, completed challenge 26

1 files changed, 32 insertions, 0 deletions

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;
+}