ECE 385 EXPERIMENT #9

9.1
ECE 385
EXPERIMENT #9
SOC with Advanced Encryption Standard in SystemVerilog
I. OBJECTIVE
In this experiment you will implement a 128-bit Advanced Encryption Standard (AES)
using SystemVerilog as an Intellectual Property (IP) core. In the first part of this lab you will
implement 128-bit AES encryption on the software IP core, in the second part of this lab you will
implement 128-bit AES decryption in SystemVerilog, and will learn to design your own
hardware IP core.
II. INTRODUCTION
An Intellectual Property (IP) core is a reusable hardware design unit that is the
intellectual property of a party. It can come in many different forms, ranging from hardware
description language (HDL) to transistor layouts. An IP core in the hardware world is analogous
to a library in the software language. The IP cores are often designed to gear towards specific
functionalities rather than complete hardware systems. An IP core is usually specified through its
inputs and outputs, with emphasis on the various design specs and performance evaluations such
as the ones we have introduced in Experiment 4.
Users of an IP core usually obtain their license from the owner of the IP core to
incorporate the IP core into their own design for extended functionality. As a notable example,
manufacturers of ARM-based processors obtain their license from ARM Holdings to design their
own processors. The owner of the ARM IP core does not manufacture its own processors, but
instead focuses on the development of the ARM architecture itself.
In this experiment, you will learn how to design a decryption IP core, and incorporate it
with your software interface through the embedded NIOS II processor to form a complete system
on chip (SoC). Through the software interface, your circuit will be able to decrypt the input data
using the provided cipher key to reconstruct the original message.
9.2
Please read the INTRODUCTION TO ADVANCED ENCRYPTION STANDARD
(IAES) and the INTRODUCTION TO THE AVALON-MM INTERFACE (IAMM).
III. PRE-LAB
A. Week 1:
Your primary task for the first week of this lab is to implement a 128-bit AES algorithm
in C and then to run that algorithm on the NIOS II-e processor. The lookup tables which
contains S-Box, Inverse S-Box, gf_mul (pre-calculated values for all possible GF(2^8)
calculations), and Rcon, is be provided to you in aes.h, while the bulk of the algorithm
will be implemented by you.
The sections for encryption include:
1. Your basic encryption input and control loop
2. A KeyExpansion function
3. An AddRoundKey function
4. A SubBytes function
5. A ShiftRows function
6. A MixColumns function
Psuedo-code is provided in the appendix for the progression through these various states,
so ideally the process should be as simple as writing each component, and then writing a
control loop that applies each step of the algorithm to the plaintext (called the state in the
appendix) in the proper sequence.
NOTE: For debugging purposes, the course website contains a table of intermediate
results. This file should allow you to figure out what sections of your AES code are
having issues.
Once this AES algorithm is working (I would suggest having 2-3 different values for the
plaintext and cipherkey that you can swap between to test it), your next task is to get the
algorithm to work on the NIOS II-e. The main barrier here is getting the JTAG UART set
up to handle input and output properly. You should already have this mostly implemented
due to Lab 8, but if you haven’t, the same set of steps applies.
9.3
For week 1, your code should have the abilities to receive plaintext and a cipher key from
the Eclipse console. It should then use your C code to encrypt the message, with the
results appearing in the console and the key on the hex displays. The course website has
some example messages and keys (with results) if you want to use them.
To display your key on the hex displays, you will also need to complete the Avalon-MM
Interface, described in IAMM, in week 1. You need to be able to send a 128 bit key to the
hardware and display the first 2 and last 2 bytes on the hex display.
For week 1, you will be required to benchmark your C code on the NIOS II/e software
core. It is sufficient to use the provided codes for benchmarking.
Week 1 Demo Point Breakdown:
1 point: Correct key expansion
1 point: Correct initial round key and looping rounds operations
1 point: Correct AES encryption test vectors
1 point: Benchmark of NIOS II/e based AES in kB/s
1 point: Correct Hardware Software communication to display the correct key on the hex
displays
B. Week 2:
For the second week, you will need to design, document, and implement a 128-bit
hardware decryption IP core in SystemVerilog that uses the AES algorithm. You will
then use Platform Designer to link the AES IP core to your project. A state machine is
REQUIRED to transition through the different AES modules, as well as to incorporate
the capabilities to initialize, run, reset, and flag the completion of the AES decryption
algorithm.
You are provided with avalon_aes_interface, AES, KeyExpansion, InvShiftRows,
InvMixColumns and SubBytes. In the previous week you should have the completed the
avalon_aes_interface to communicate between hardware and software and should also
have a working Platform Designer environment.
To complete the decryption algorithm, you should need to modify AES.sv. You need to
make a state machine to handle the looping of the AES algorithm. Since you are only
allowed to include one instance of InvMixColumns you need to handle creating
additional states in the above state machine or add another state machine. Using the
9.4
Hardware/Software interface you should be able to output the decrypted plaintext to the
terminal. For simulating the AES decryption part, you may set AES.sv as the top-level
entity temporarily, and write a testbench to simulate AES.sv directly.
For week 2 you will benchmark your HDL decryption core, separate from the encryption
step. You can also use the provided codes for this step.
You will need to bring the following to the lab:
1. Your code for the Lab.
2. Block diagram of your design with components, ports, and interconnections labeled.
3. An annotated simulation of the AES decryption core showing the correct state transition
of the AES state machine.
Week 2 Demo Point Breakdown:
1 point: Correctness of a single looping round operation. (on-board)
1 point: Correctness of stepping through the looping rounds using state machine. (onboard)
1 point: Transmitting correct result to NIOS II-e and displaying plaintext via terminal
1 point: Able to run consecutive decryption operations correctly without restarting the
program.
1 point: Show benchmark results for HDL based AES decryption in kB/s
IV. LAB
Follow the Lab 9 demo information on the course website.
V. POST-LAB
1.) Refer to the Design Resources and Statistics in IQT.25-27 and complete the following
design statistics table.
LUT
DSP
Memory (BRAM)
Flip-Flop
9.5
Frequency
Static Power
Dynamic Power
Total Power
Document any problems you encountered and your solutions to them, and provide a short
conclusion. Before you leave, submit your latest project code including both the .sv files and the
software code to your TA on his/her USB drive. The TAs are under no obligation to accept late
code or code files that are intermixed with other project files.
2.) Answer the following questions in the lab report
• Which would you expect to be faster to complete encryption/decryption, the software or
hardware? Is this what your results show?
• If you wanted to speed up the hardware, what would you do? (Note: restrictions of this
lab do not apply to answer this question)
VI. REPORT
In your lab report, should hand in the following:
• An introduction;
• Written description of the operation of your circuit;
• Written purpose and operation of each entity;
• State diagram for the decryption process;
• Schematic block diagram with components, ports, and interconnections labeled;
• Annotated prelab simulation waveforms showing the correct state transition of the AES
decryption core;
• Answers to postlab questions;
• A conclusion regarding what worked and what didn’t, with explanations of any possible
causes and the potential remedies.