Extended Tiny Encryption Algorithm (XTEA)

Questions and reports to

s0559122@htw-berlin.de

Description

This repository was a project of my University HTW-Berlin in the subject Embedded Systems, first Master Semester. The Algorithm XTEA is divided into two algorithms.

1. Encrypt-Algorithm
2. Decrypt-Algorithm

Each algorithm is written in a single VHDL-File, can be found in folder software. There are no Testbench available, but I tested both VHDL-Files intensively. All the code was running on a ZedBoard Zynq-7000 ARM/FPGA SoC Development Board which has a ARM-Controller on board. On this ARM-Controller runs a Petalinux. Maybe others Linux Distribution works also. The C-Code for communicating with the FPGA is also available on folder software.

XTEA has a loop in it, but implementing loops on a FPGA is difficult. Therefore I choose 64 steps for each algorithm encrypting & decrypting, before the user is allowed to choose this and the FPGA has no more space on it. So I used the maximum of XTEA for this FPGA. All of the VHDL-Code was written with Vivado.

Structure

• software -> VHDL-Code & C-Code
• vivado_files -> All files for flashing the FPGA

For understanding why these both folders needed, are explained in section "Getting started".

Getting Started

Requirements

• Cloned these repository
• Installed Vivado
• Running Petalinux (or other) on ARM-Controller of the Zynq Board
• Connection (I used SSH) to Petalinux.
• Simple Linux computer for cross-compiling the C-Code

1.

The C-Code must be cross-compiled for Petalinux. If you can compile directly on the ARM Controller do it. I can't, so I used the command

arm-linux-gnueabihf-gcc code.c -o output

The Code should compile without any warnings or errors. Incase of problems contact me.

2.

Transfer (Linux: scp-command is the default tool for this purpose) the compiled hex-code (in my case output) to the ARM-Controller (Petalinux).

3.

Open Vivado and load the file

vivado_files/zynq-system/zynq_system.xpr

It should look like on the picture. I used a another path so keep clear of confusion.

Then flash the Code to the FPGA. For this no Bitstream-File or anything needed. First we need to connect the Board with Viado. On the left side by

• Project Manager
• press "Generate Bitstream" (takes ~30min)
• press "Open Hardware Manager" (at the bottom)
• press "Open Target"
• press "Auto Connect" Make sure this is successfully Now we flash the program
• Project Manager
• press "Open Hardware Manager" (at the bottom)
• press "Program Device"

4.

After this we can execute the program on Petalinux. Normally this should work perfectly. If not, contact me and send me a screenshot of the output.

./output

Conclusion

With this project it is possible to create a prototype for a encryption & decryption device. Maybe for transfering very sensitive data which can be decrypted only with custom hardware.

Further Ideas

Pipelining of data. With this it is possible to encrypt & decrypt a bunch of data in almost zero time.