### Backdoors in Block Ciphers, Theory and Practice

Description: The main question is that given a complex structure of some real-life cipher can we design an S-box which makes this cipher weaker than expected.

Prerequisites: Strong algebra required, COMPGA18 obligatory, matrices, polynomials, Boolean functions, ANF, Differential Linear and Generalized Linear Cryptanalysis, some scientific programming background with polynomials in C++ or SAGE maths, SAT solvers and other software tools for cryptanalysis.

### Blockchain Forensics in Bitcoin and other crypto currencies

Description: We are going to mine large quantities of data about blockchain transactions and look at certain specific types of events and how they are related.

Prerequisites: COMPGA12, programming, visualization, machine learning, working large databases.

### Recovery of Private Keys for Bitcoin Wallets

Description: We are going to study how provate keys can be recovered in specific attacks scenarios and design optmized key recovery techniques. We will study possibilities offered by new upgrades of bitcoin with Schnorr signatures etc.

Prerequisites: COMPGA18,maths, programming, algebra, digital signatures, elliptic curves.

### RowHammer attacks on Block Ciphers and Google Authenticator

Description:

We will design a fine grained RowHammer attack able to perturbate certain specific memory locations in order to extract the secret key from a cryptographic algorithm.

Prerequisites: COMPGA18, block ciphers, hash functions, good programming, maths.

### Private Key Recovery Side Channel Attacks on Crypto Currency Wallets

Description: We will study key derivation BIP32/44/48 standards, RF6979, HMAC, SHA256 and SHA256 and OpenSSL rng, and see how exactly these are or can be implemented and see how these can be attacked by a RowHammer attack in theory and in practice.

Prerequisites: COMPGA12, COMPGA18, COMPGA03 intro to cryptography, good programming, maths.

### Ransomware and Blockchain Forensics

We are going to study how ransomware propagates and operates. Mine data about payments. Detect specific events and monitor and analyse malware also.

**Prerequisites:** COMPGA12,programming, visualization, machine learning, working large databases.

### Segregated Witness Digital Signatures and Off-Chain Payments in Bitcoin

We will study possibilities offered by new upgrades of bitcoin with Schnorr signatures.

**Prerequisites:** COMPGA12, COMPGA03 intro to cryptography, good programming, maths.

### Cold War Cryptography and Modern Block Ciphers

##### Description

We will study how various historical ciphers such as East-German T-310, Russian GOST cipher etc. We will exploit correlation, LC, DC, self-similarity, fixed points, involutions, reflection attacks etc.

##### Prerequisites

Maths, good grade in all cryptography modules, maybe some programming.

### Cryptanalysis of T-310

We will study the T-310 stream cipher used by Eastern German government during the Cold War. We will study the applicability of all known classical attacks on block and stream ciphers.

**Prerequisites:** COMPGA18 obligatory, good maths, matrices, polynomials, Boolean functions, ANF.

### Efficient Algebraic Coding of ECC Problems

We will study some selected topics covered in this paper such as D73 Theorem page 61. The main problem is given a set of solutions defined by ECC relations and constraints what is the most efficient method to encode them as low degree polynomial equations mod P? Another problem is, can such systems of equations be solved by software at a reasonable cost? A key problem is how the complexity of algebraic coding can be reduced by using redundant expansions on the set of variables. We dispose of a ready

suite of software solutions which allows one to explore these problems.

**Prerequisites:** COMPGA12 ECC labs, COMPGA18 Cryptanalysis obligatory, maths/algebra, scientific programming with polynomials in C/C++ or SAGE maths.