KRYPTOG Logs

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

The Kasiski test (1863) was the first modern cryptanalytic method — it broke the Vigenère cipher that had been considered unbreakable for nearly 300 years. * The Kasiski test: repeated sequences to distances to GCD to key length. * Published by Friedrich Wilhelm Kasiski in 1863,...

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

The four goals are: (1) Confidentiality/Privacy, (2) Data Integrity, (3) Authentication, and (4) Non-repudiation. From [MOV], the standard reference work: Goal Definition Confidentiality Keeping information content secret from unauthorized parties. Synonymous with privacy...

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

The One-Time Pad is the only cipher that is provably, information-theoretically secure — it's mathematically impossible to break, even with unlimited computing power. * One-time pad: ciphertext = plaintext XOR a random, single-use key. * Invented by Gilbert Vernam in 1918 (paten...

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

The Enigma had a key space of ~10^17 (approximately 56 bits), which was considered unbreakable in the 1940s but was defeated because structural weaknesses drastically reduced the effective key space. Key facts: The Enigma's rotor system produced ~10^17 possible configurations Th...

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

Encryption (Verschlüsselung) only prevents unauthorized reading — it does NOT prevent an attacker from modifying the ciphertext, which will decrypt to corrupted or attacker-controlled plaintext. A core principle of applied cryptography, memorably stated in German as "Verschlüssel...

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