Applied Cryptography

Applied Cryptography Robust Software Quantum Safety Machine Learning Applied to Security Analysis and Exploration of Vulnerabilities Computer Systems Forensic Analysis Reverse Engineering Identification, Authentication and Authorization Secure Execution Environments Direito da Organização e da Segurança

Applied Cryptography
Classical (Symmetric) Cryptography
Modern Symmetric Cryptography
Cipher Modes
Cryptographic Hashing
RSA & Related Subjects
Asymmetric Key Management
Digital Signatures

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Goals
Attacks
Approaches

Cryptanalysis

PreviousComputational Security NextPractical Approaches

Last updated 1 year ago

Goals

Discover original plaintext.
- Which originated a given ciphertext.
Discover a cipher key.
- Allows the decryption of ciphertexts created with the same key.
Discover the cipher algorithm.
- Or and equivalent algorithm.
- Usually algorithms are not secret, but there are exceptions.
  - Lorenz, A5 (GSM), RC4 (WEP), Crypto-1 (Mifare)
  - Algorithms for DRM (Digital Rights Management)
- Reverse engineering.

Attacks

Approaches

Brute force

Exhaustive search along the key space until finding a sutable key.

Usually infeasible for a large key space.

e.g. 2¹²⁸ random keys (or keys with 128 bits).
Randomness is fundamental!

Cleaver attacks

Reduce the search space to a smaller set of potential candidates.