Cryptanalysis
Definition
The study of breaking cryptographic systems. Complement to cryptography. Goals include recovering the key, recovering the plaintext, or distinguishing a cipher's output from random.
- Field
- Study of breaking cryptographic systems
- Complement to
- Cryptography
- Goal 1
- Recovering the encryption key
- Goal 2
- Recovering plaintext or distinguishing output from random
Common questions
Does successful cryptanalysis always mean recovering the exact key?+
No. A weakness can be exploited even without fully recovering the key, for example by distinguishing encrypted output from truly random data or by recovering the plaintext of a specific message through a side channel, either of which counts as a break for practical purposes.
Where does cryptanalysis fit into digital forensic investigations?+
It becomes relevant when an examiner encounters encrypted evidence protected by a weak, outdated, or misconfigured cipher, since a documented cryptanalytic attack against that specific algorithm or implementation may allow lawful recovery of the underlying data.
Related terms
- Brute Force
- Exhaustive search over the key space. The benchmark every other attack must beat. AES-128 brute force is computationally infeasible on classical hardware;...
- Diffie-Hellman
- Key exchange protocol by Diffie, Hellman and Merkle (1976) that lets two parties agree on a shared secret over a public channel....
- Padding Oracle
- An attack that uses an error-message distinction (or a timing distinction) between 'padding invalid' and 'authentication invalid' to recover plaintext from CBC-mode...
- Perfect Forward Secrecy (PFS)
- Property of a key exchange where compromise of a long-term private key does not let the attacker decrypt past sessions. Achieved by...
- Post-Quantum Cryptography (PQC)
- Algorithms designed to resist attacks by sufficiently capable quantum computers. NIST standardised CRYSTALS-Kyber as ML-KEM and CRYSTALS-Dilithium as ML-DSA in 2024.
- Side-Channel Attack
- Attack that exploits information leaked by a correct implementation: timing, power consumption, electromagnetic emanation, cache state, acoustic noise. Independent of the algebra...