Hacking Cryptography

TIME: 09:00 to 17:00 CEST/GMT+2

Virtually all digital communication is secured using cryptography. Our laptops, phones, printers, cars, bank cards and washing machines use cryptography to keep things confidential, to make sure messages aren’t tampered with and to establish secure connections. However, even though modern security heavily relies on it, cryptography is complex and oftentimes fragile. This in-depth training shows how cryptography is misused in practice. Moreover, participants will learn how common cryptography screwups can be exploited. To foster skills, participants will write their own exploits and use them on real world systems provided by us.

Agenda

Day 1:

Basic Terminology

• Cryptography
• Primitives
• Security Guarantees
• “Oracles”

Python

• Basics of Python
• Using Python on Raw Bits and Bytes
• Using Python for Bignum Computation
• **Challenge Lab: Python**

Attacks on Symmetric Crypto

Stream Ciphers

• Introduction to Stream Ciphers
• The One Time Pad and XOR Ciphers
• Salsa20/Chacha, RC4
• Exploiting Output Bias
• Leveraging Partialy Known Plaintext
• Nonce Reuse Attacks
• (Compression) Side Channels
• **Challenge Lab: Hacking Stream Ciphers**

Block Ciphers

• Introduction to Block Ciphers
• AES, DES, 3DES
• Modes of Operation (ECB, CBC, CTR, XTS)
• Block Shuffling Attacks
• Nonce Reuse Attacks
• Bit-Flipping Attacks
• Padding Oracles
• **Challenge Lab: Hacking Block Ciphers**

Hash Functions

• Introduction to Hash Functions
• Collision Attacks (SHA1/MD5)
• Length Extension Attacks
• Rainbow Table Attacks
• **Challenge Lab: Hacking Hash Functions**

Day 2:

Attacks on Message Authentication Codes

• Introduction to Message Authentication Codes
• Attacks on Primitive Constructs
• Forgery Attacks
• Authenticated Encryption
• GCM Forbidden Attack
• **Challenge Lab: Hacking MACs**

Entropy Attacks

• Introduction to the Linux Entropy Pool
• Misuse of Pseudo Random Number Generators
• Predicting Linear Congruential Generators
• Predicting Mersenne Twister
• Predicting Linear Feedback Shift Registers
• The Dual EC DRBG Backdoor
• **Challenge Lab: Hacking Randomness**

Attacks on Asymmetric Crypto / RSA

• Introduction to RSA
• RSA Key Formats
• Attacks on Textbook RSA
• Attacks on Short Keys
• Forging RSA Signatures
• RSA PKCS#1.5 Signatures
  * Padding/Bleichenbacher Attacks on RSA
• **Challenge Lab: Hacking RSA**

Day 3:

Attacks on Asymmetric Crypto / ECC

• Introduction to Elliptic Curve Cryptography
• The Java ECC Screwup
• Exploiting ecDSA Nonce Reuse
• Exploiting ed25519 Bad Public Keys
• Invalid Point Attacks
• **Challenge Lab: Hacking ECC**

Certificates

• Introduction to Certificates
• x509 structure
• Common certificate pitfalls
• **Challenge Lab: Working with Certificates**

Further Attacks

• JWT Implementation Bugs
• TLS Weaknesses
• **Challenge Lab: Exploiting JWT**

Outlook

• Sneak Peak at Post Quantum Crypto

Farewell

• **Presentation of Take Home Challenges**
• Recap – Cryptography