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Cryptography divides into symmetric (one shared secret key), asymmetric (a public/private key pair), and protocols that combine those primitives — and a complete key-usage split adds the unkeyed primitives, above all hash functions, which use no key at all. * Cryptography by key...

Quiz: KRYPTOG / Introduction to Cryptology | updated: Sep 16, 2026

The binomial coefficient $\binom{n}{k} = \frac{n!}{k!\,(n-k)!}$ counts the number of ways to choose $k$ items from $n$, and it drives the probability estimates behind cryptanalysis — above all the birthday attack. * The birthday paradox: counting $\binom{n}{2}$ pairs, a collisio...

Quiz: KRYPTOG / Symmetric Cryptography | updated: Sep 16, 2026

The drone scenario requires encryption (confidentiality of commands/footage), authentication (prevent unauthorized control), integrity (prevent command modification), and non-repudiation (logging who issued commands). The drone communication faces all classic attacks: Threat A...

Quiz: KRYPTOG / Fundamentals of Cryptography | updated: Sep 16, 2026

In symmetric encryption $K_E = K_D$ — the same secret key is used for both encryption and decryption, providing only confidentiality (not integrity). How it works: Alice and Bob share a secret key $K$ Alice encrypts: $c = E(K, m)$ Bob decrypts: $m = D(K, c)$ Provides: Confident...

Quiz: KRYPTOG / Fundamentals of Cryptography | updated: Sep 14, 2026

A provably secure cryptosystem is one where breaking the cipher is mathematically proven to be as hard as solving a known hard problem — the Rabin system has this property, but RSA does not. Rabin cryptosystem: Breaking Rabin is provably equivalent to solving the integer factori...

Quiz: KRYPTOG / Introduction to Cryptology | updated: Aug 02, 2026

Authentisierung is the process of verifying identity; Authentizität is the property of being genuine. One is an action, the other is a state. According to the BSI (Bundesamt für Sicherheit in der Informationstechnik — Germany's Federal Office for Information Security): Term Ty...

Quiz: KRYPTOG / Introduction to Cryptology | updated: Aug 02, 2026

The Vigenère cipher is a polyalphabetic substitution cipher that uses a keyword to shift each letter by a different amount, defeating simple frequency analysis. * Vigenere: a keyword gives each position its own shift. * Invented by Blaise de Vigenère in 1586 (building on ideas f...

Quiz: KRYPTOG / Introduction to Cryptology | updated: Aug 02, 2026

Non-repudiation of origin prevents a sender from denying they sent a message; non-repudiation of receipt prevents a receiver from denying they received it. The BSI distinguishes: Type German Protection against... Non-repudiation of origin Nichtabstreitbarkeit der Herkunft...

Quiz: KRYPTOG / Introduction to Cryptology | updated: Aug 02, 2026

Frequency analysis exploits the fact that in any language, certain letters appear more often — so the most frequent letter in ciphertext likely corresponds to the most common letter in the language. * Letter frequencies survive a monoalphabetic cipher and give away the key. * Ho...

Quiz: KRYPTOG / Introduction to Cryptology | updated: Aug 02, 2026

MPC allows multiple parties to jointly compute a function over their private inputs without revealing those inputs to each other — replacing the need for a trusted third party. * Secure multi-party salary averaging: a random offset R hides each input. * The classic example (sala...

Quiz: KRYPTOG / Introduction to Cryptology | updated: Aug 02, 2026