The first task was similar to the one from the MI-HWB course. We were operating with oscilloscopes measuring power consumption of a small java card device. This java card was encrypting accepted data using AES with an unknown hardcoded key. Our task was to break the cipher and get the key providing plain and corresponding cipher texts.
Power analysis takes an advantage from correlation analysis of power consumption measurements. The attack exploits biases varying power consumption of microprocessors or other hardware while performing operations using secret keys.
You can find Matlab and GNU Octave source codes in the directory.
My assignment was to implement the PRESETNT cipher for AVR with atmega163 CPU. The destination device was a simple AVR-based card controlled by sending signals using USB client application.
Actual implementation was inspired by an open-source implementation taken from the github. It takes place in the example_PRESENT.c file. You can change the hardcoded key in crypt.h.
To build a solution please use AVR studio and proceed as usually.
- Using the AVR studio build the project
- Flash the output
- Connect the card to a computer using the Java Smart Card client
- Call the encryption method via:
CLA: 0x80andINS: 0x60
My task task to implement Elliptic curve operations necessary for adding two points. Prior to that I had to implement GF(p) operations such as addition, multiplication, inversion and comparison. Every result of each operation is a residual of division with prime number as a modulus. I have implemented operation over Montgomery domain as well. Montgomety domain is a special domain created to avoid inversion as the most expensive operation in terms of runtime.
All operations are done in fixed length arighmetics - to change the length change the following lines in poly.h:
#define BYTES_CNT 10
#define BITS_CNT 80The prime number can be set in the function ECinit ec.cpp.
- Using the Arduino IDE build and flash Arduino
- Connect the device via serial port and wait for instructions
- Output of the point addition should be sent back
This task was an extension over the previous one. I had to implementan addition operations allowing user to compute scalar sum of the chosen point A = n*K.
To speed up processing on such a lowend device arduino is I incorporated the double and add algorithm. It is very similar to the well-known square and multiply algo.
The rest is very similar to the previous task.
- Using the Arduino IDE build and flash Arduino
- Connect the device via serial port and wait for instructions
- Output of the point addition should be sent back