Cryptanalytic Attacks — CISSP Study Guide

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Attack	What the attacker has / does	What it targets	Primary defense
Brute force	Tries every key	Key space	Adequate key length; rate limiting
Ciphertext-only	Only encrypted output	Cipher weakness	Strong standardized cipher
Known-plaintext	Some plaintext-ciphertext pairs	Cipher weakness	Cipher resistant to known plaintext
Chosen-plaintext / chosen-ciphertext	Encrypts or decrypts chosen inputs	Cipher / oracle	CCA-secure scheme; authenticated encryption
Frequency analysis	Letter/pattern statistics	Substitution ciphers	Modern block/stream ciphers
Birthday / collision	Finds two inputs with same hash	Hash output length	Long-output collision-resistant hash
Side-channel (timing/power/EM/cache)	Measures physical leakage	Implementation	Constant-time code; masking/blinding
Fault injection	Induces computation errors	Implementation	Error detection; tamper response
MITM	Relays and alters traffic	Key exchange / channel	Mutual auth; certificate validation
Pass-the-hash / Kerberos exploitation	Reuses captured hash or ticket	Credential reuse	Credential hygiene; ticket protection; monitoring
Replay	Resends captured messages	Protocol freshness	Nonces, timestamps, sequence numbers
Ransomware	Encrypts victim data, demands ransom	Availability	Tested offline/immutable backups; segmentation

Cheat sheet

Classify a cryptanalytic attack by attacker access, not by the algorithm
The analytic attacks form a ladder of increasing attacker access
Known-plaintext means captured pairs; chosen-plaintext means the attacker controls the input
Brute force sets the floor, defeated by adequate key length
Frequency analysis breaks classical substitution ciphers
A birthday attack finds a hash collision in about 2^(n/2) work
Meet-in-the-middle is why double encryption barely helps
Side-channel attacks read physical leakage, not the ciphertext
Fault-injection attacks force errors so the faulty output reveals the key
Put keys an attacker can physically reach in a FIPS 140-validated module
A man-in-the-middle attacker relays and alters traffic between two parties
Replay attacks resend captured messages; freshness defeats them
Pass-the-hash authenticates with a stolen hash, never cracking the password
A golden ticket forges TGTs from the KRBTGT secret
Kerberoasting cracks service-account passwords offline from service tickets
Ransomware uses strong cryptography against you, so recoverability is the defense
A system's strength is the cheapest known attack, not its key length
SPA reads one trace by eye; DPA correlates many traces statistically

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Cheat sheet