diff --git a/sol/set2.c b/sol/set2.c
index 13f7223..924b50f 100644
--- a/sol/set2.c
+++ b/sol/set2.c
@@ -75,9 +75,6 @@ TCASE(ecb_encrypt_decrypt_single_block)
     CHECK(memcmp(decode.output, expected_result, 16) == 0);
     free(encode.output);
     free(decode.output);
-    //CryptoAttribs_t::Free(&encode);
-    //CryptoAttribs_t::Free(&decode);
-    //Key_t::Free(&key1);
 }
 TCASE_E
 
diff --git a/src/common.h b/src/common.h
index e1e3119..2b0e582 100644
--- a/src/common.h
+++ b/src/common.h
@@ -21,6 +21,7 @@ void __CheckFunc__(bool iFlag, const char* const file, int line, const uint8_t*
 // Some useful defines
 #define MIN(a,b) a<b ? a : b
 #define ROUNDUP_16_BYTES(X) (((X+15)/16) * 16)
+#define AES_BLOCK_SIZE 16
 
 #define OP_CHECK(exp)                                           \
     do {                                                        \
@@ -47,6 +48,28 @@ typedef enum {
   kPadding_PKCS7
 } PaddingType;
 
+typedef struct CtrCtx_t {
+  uint8_t nonce[8];
+  uint8_t counter[8];
+  uint8_t encrypted_counter[AES_BLOCK_SIZE];
+} CtrCtx_t;
+
+typedef struct ModeCtx_t {
+  uint8_t iv[AES_BLOCK_SIZE];
+  CtrCtx_t ctr;
+} ModeCtx_t;
+
+/* -------------------------------------------------------------------------
+   Structure for key passing
+   -------------------------------------------------------------------------*/
+typedef struct Key_t {
+  uint8_t* key;
+  size_t   len;
+
+  static void Init(Key_t* ctx);
+  static void Free(Key_t* ctx);
+} Key_t;
+
 /* -------------------------------------------------------------------------
    Struct used for symmetric encryption
    -------------------------------------------------------------------------*/
@@ -57,25 +80,18 @@ struct  CryptoAttribs_t {
 	size_t	 output_len;
 	uint8_t* iv;
 	size_t   iv_len;
+  uint64_t output_cursor;
+
 	CryptoOperation  operation;
+  ModeCtx_t mode;
   // If requested, padding will align produced block size with key size
   PaddingType padding;
+  Key_t key;
 
 	static void Init(CryptoAttribs_t* ctx);
 	static void Free(CryptoAttribs_t* ctx);
 };
 
-/* -------------------------------------------------------------------------
-   Structure for key passing
-   -------------------------------------------------------------------------*/
-struct Key_t {
-	uint8_t* key;
-	size_t	 len;
-
-	static void Init(Key_t* ctx);
-	static void Free(Key_t* ctx);
-};
-
 struct int24 {
 	unsigned int data:24;
 };
diff --git a/src/enc_modes.h b/src/enc_modes.h
index a89936a..7eaa501 100644
--- a/src/enc_modes.h
+++ b/src/enc_modes.h
@@ -3,7 +3,8 @@
 
 #include "common.h"
 
-Result_t crypt( CryptoAttribs_t* attribs, const Key_t* const key );
+void process_block(uint8_t in[16], uint8_t out[16], const Key_t* const key, bool encrypt);
+Result_t aes_whole_blocks( CryptoAttribs_t* attribs, const Key_t* const key );
 
 Result_t cbc_encrypt( CryptoAttribs_t* attribs, const Key_t* const key );
 Result_t cbc_decrypt( CryptoAttribs_t* attribs, const Key_t* const key );
diff --git a/src/main.cpp b/src/main.cpp
index 0407a8a..42c3602 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1,5 +1,6 @@
 #include "sol/set1.h"
 #include "sol/set2.h"
+#include "sol/set3.h"
 #include "tst/utils.h"
 
 #include <openssl/conf.h>
@@ -13,9 +14,10 @@ int main()
     ERR_load_crypto_strings();
     OpenSSL_add_all_algorithms();
 
+    SET3::run();
 
-    SET2::run();
     SET1::run();
+    SET2::run();
     UTILS::run();
 
     /* Clean up */