\babel@toc {ngerman}{}
\contentsline {chapter}{\numberline {1}Substitionsverfahren}{4}%
\contentsline {section}{\numberline {1.1}Skytale}{4}%
\contentsline {section}{\numberline {1.2}Monoalphabetische Substitionsverfahren}{4}%
\contentsline {subsection}{\numberline {1.2.1}Caesar-Verschlüsselung}{5}%
\contentsline {subsection}{\numberline {1.2.2}Häufigkeitsanalyse}{5}%
\contentsline {section}{\numberline {1.3}Polyalphabetische Substitutionsverfahren}{5}%
\contentsline {subsection}{\numberline {1.3.1}Vignère-Verfahren}{5}%
\contentsline {subsubsection}{\numberline {1.3.1.1}Verschlüsselung}{5}%
\contentsline {subsection}{\numberline {1.3.2}One-Time-Pad}{6}%
\contentsline {subsubsection}{\numberline {1.3.2.1}Verschlüsselung}{6}%
\contentsline {subsubsection}{\numberline {1.3.2.2}Perfekte Sicherheit}{6}%
\contentsline {section}{\numberline {1.4}algebraische Substitionsverfahren}{6}%
\contentsline {subsection}{\numberline {1.4.1}Hill-Verfahren}{6}%
\contentsline {subsubsection}{\numberline {1.4.1.1}Verschlüsselung}{6}%
\contentsline {subsubsection}{\numberline {1.4.1.2}Entschlüsselung}{6}%
\contentsline {chapter}{\numberline {2}Modulare Arithmetik}{7}%
\contentsline {section}{\numberline {2.1}Exkurs: Division mit Rest}{7}%
\contentsline {section}{\numberline {2.2}Der Ring $\mathbb {Z}_n$}{7}%
\contentsline {subsection}{\numberline {2.2.1}Addition und Multiplikation}{7}%
\contentsline {subsubsection}{\numberline {2.2.1.1}Inverse bezüglich der Addition}{7}%
\contentsline {subsubsection}{\numberline {2.2.1.2}Inverse bezüglich der Multiplikation}{7}%
\contentsline {subsection}{\numberline {2.2.2}Subtraktion}{8}%
\contentsline {subsection}{\numberline {2.2.3}Teiler, Vielfache}{8}%
\contentsline {subsubsection}{\numberline {2.2.3.1}Teilerregeln}{8}%
\contentsline {subsection}{\numberline {2.2.4}Kongruenz}{8}%
\contentsline {subsection}{\numberline {2.2.5}Matrizen}{8}%
\contentsline {subsubsection}{\numberline {2.2.5.1}Determinantenberechnung}{8}%
\contentsline {subsubsection}{\numberline {2.2.5.2}Inverse Matrix}{8}%
\contentsline {section}{\numberline {2.3}Der erweiterte Euklid'sche Algorithmus}{8}%
\contentsline {subsection}{\numberline {2.3.1}Euklid'scher Algorithmus}{9}%
\contentsline {subsection}{\numberline {2.3.2}erweiterter Euklid'scher Algorithmus}{9}%
\contentsline {subsubsection}{\numberline {2.3.2.1}Beispiel}{9}%
\contentsline {section}{\numberline {2.4}Euler'sche $\varphi $-Funktion}{10}%
\contentsline {subsection}{\numberline {2.4.1}$\varphi $-Funktion und Primzahlen}{10}%
\contentsline {chapter}{\numberline {3}IT-Sicherheit: Gefährdungen und Maßnahmen}{11}%
\contentsline {section}{\numberline {3.1}Vertraulichkeit}{11}%
\contentsline {subsection}{\numberline {3.1.1}Schutzmaßnahmen: Verschlüsselungsverfahren}{11}%
\contentsline {section}{\numberline {3.2}Integrität}{11}%
\contentsline {subsection}{\numberline {3.2.1}Schutzmaßnahme: Hashfunktionen, Whitelists}{12}%
\contentsline {section}{\numberline {3.3}Authenzität der Daten}{12}%
\contentsline {subsection}{\numberline {3.3.1}Schutzmaßnahme: Signaturen}{12}%
\contentsline {subsection}{\numberline {3.3.2}Schutz vor Replay-Angriffen}{12}%
\contentsline {section}{\numberline {3.4}Authenzität von Nutzern}{12}%
\contentsline {subsection}{\numberline {3.4.1}Schutzmaßnahmen}{12}%
\contentsline {section}{\numberline {3.5}Zugriffskontrolle}{12}%
\contentsline {subsection}{\numberline {3.5.1}Schutzmaßname: Zugriffskontrollsystem}{13}%
\contentsline {section}{\numberline {3.6}Nichtabstreitbarkeit, Verbindlichkeit}{13}%
\contentsline {subsection}{\numberline {3.6.1}Schutzmaßname: Signaturen und PKI}{13}%
\contentsline {section}{\numberline {3.7}Verfügbarkeit}{13}%
\contentsline {subsection}{\numberline {3.7.1}Schutzmaßnahmen}{13}%
\contentsline {section}{\numberline {3.8}Anonymität}{13}%
\contentsline {chapter}{\numberline {4}Verschlüsselungsverfahren}{14}%
\contentsline {section}{\numberline {4.1}Das Kerckhoffs'sche Prinzip}{14}%
\contentsline {section}{\numberline {4.2}Mathematische Modelierung von Verschlüsselungsverfahren}{14}%
\contentsline {section}{\numberline {4.3}Schlüsselaustausch}{14}%
\contentsline {section}{\numberline {4.4}Angriffsszenarien}{15}%
\contentsline {subsection}{\numberline {4.4.1}Ciphertext-only Angriffe}{15}%
\contentsline {subsection}{\numberline {4.4.2}Known-plaintext Angriffe}{15}%
\contentsline {subsection}{\numberline {4.4.3}Chosen-plaintext Angriffe}{15}%
\contentsline {section}{\numberline {4.5}Brute-Force Angriffe}{15}%
\contentsline {subsection}{\numberline {4.5.1}Beispiel: Brute-Force Angriff auf $k$}{15}%
\contentsline {subsection}{\numberline {4.5.2}Beispiel: Brute-Force Angriff auf $m$}{15}%
\contentsline {subsection}{\numberline {4.5.3}Anforderungen zum Schutz vor Brute-Force}{15}%
\contentsline {section}{\numberline {4.6}Wörterbuchangriffe}{16}%
\contentsline {subsection}{\numberline {4.6.1}Schutz vor Wörterbuchangriffen}{16}%
\contentsline {subsubsection}{\numberline {4.6.1.1}Nonce-Verschlüsselung}{16}%
\contentsline {chapter}{\numberline {5}Stromverschlüsselungsverfahren}{17}%
\contentsline {section}{\numberline {5.1}Synchrone Stromverschlüsselungsverfahren}{17}%
\contentsline {section}{\numberline {5.2}Zustandsabhängige Stromverschlüsselungsverfahren}{18}%
\contentsline {subsection}{\numberline {5.2.1}Additive zustandsabhängige Stromverschlüsselungsverfahren}{19}%
\contentsline {subsubsection}{\numberline {5.2.1.1}Synchrone additive Stromverschlüsselungsverfahren}{19}%
\contentsline {section}{\numberline {5.3}Schlüsselstrom vs. One-Time-Pad}{20}%
\contentsline {section}{\numberline {5.4}Nonces zur Initialisierung eines Schlüsselstromgenerators}{20}%
\contentsline {section}{\numberline {5.5}ChaCha20}{21}%
\contentsline {section}{\numberline {5.6}Cipher-Instanzen: Verschlüsselungsalgorithmen in Java-Laufzeitumgebungen}{22}%
\contentsline {chapter}{\numberline {6}Blockverschlüsselungsverfahren}{23}%
\contentsline {section}{\numberline {6.1}Padding-Verfahren}{23}%
\contentsline {section}{\numberline {6.2}Betriebsmodi}{23}%
\contentsline {subsection}{\numberline {6.2.1}ECB (Electronic Code Book)}{23}%
\contentsline {subsection}{\numberline {6.2.2}CBC (Cipher Block Chaining)}{24}%
\contentsline {subsection}{\numberline {6.2.3}CBC-CS (Chiphertext Stealing for CBC Mode)}{25}%
\contentsline {subsubsection}{\numberline {6.2.3.1}CBC-CS1}{25}%
\contentsline {subsubsection}{\numberline {6.2.3.2}CBC-CS2}{26}%
\contentsline {subsubsection}{\numberline {6.2.3.3}CBC-CS3}{26}%
\contentsline {subsection}{\numberline {6.2.4}CTR (Counter)}{26}%
\contentsline {subsection}{\numberline {6.2.5}OFB (Output Feedback)}{26}%
\contentsline {subsubsection}{\numberline {6.2.5.1}OFB-8$n$}{27}%
\contentsline {subsection}{\numberline {6.2.6}CFB (Cipher-Feedback)}{27}%
\contentsline {subsubsection}{\numberline {6.2.6.1}CFB-8$n$}{27}%
\contentsline {section}{\numberline {6.3}Konstruktionsprinzipien von Blockverschlüsselungsverfahren}{28}%
\contentsline {section}{\numberline {6.4}DES}{28}%
\contentsline {subsection}{\numberline {6.4.1}Triple-DES (3DES)}{28}%
\contentsline {section}{\numberline {6.5}Meet-in-the-Middle-Angriff}{29}%
\contentsline {section}{\numberline {6.6}AES (Advanced Encryption Standard)}{30}%
\contentsline {subsection}{\numberline {6.6.1}AES-128}{30}%
\contentsline {chapter}{\numberline {7}Hashfunktionen}{32}%
\contentsline {section}{\numberline {7.1}schwache Kollisionsfreiheit}{32}%
\contentsline {section}{\numberline {7.2}\texttt {MessageDigest}-Instanzen: Hashfunktionen in Java}{32}%
\contentsline {section}{\numberline {7.3}Anwendungsbeispiele}{33}%
\contentsline {subsection}{\numberline {7.3.1}Anwendungsbeispiel: Passwortdatei}{33}%
\contentsline {subsubsection}{\numberline {7.3.1.1}Anwendungsbeispiel: Passwortdatei mit Salt und Iteration Count}{33}%
\contentsline {subsection}{\numberline {7.3.2}Anwendungsbeispiel: Integritätsschutz von Dateien}{33}%
\contentsline {subsection}{\numberline {7.3.3}Anwendungsbeispiel: Integritätsschutz bei einem Dateidownload}{33}%
\contentsline {section}{\numberline {7.4}Brute-Force-Angriffe auf Hashfunktionen}{33}%
\contentsline {subsection}{\numberline {7.4.1}Brute-Force-Urbildsuche}{33}%
\contentsline {subsection}{\numberline {7.4.2}Brute-Force-Kollisionssuche}{34}%
\contentsline {section}{\numberline {7.5}Konstruktionsverfahren von Hashfunktionen}{34}%
\contentsline {chapter}{\numberline {8}MAC-Verfahren}{36}%
\contentsline {section}{\numberline {8.1}HMAC}{36}%
\contentsline {section}{\numberline {8.2}CMAC, CBC-MAC}{36}%
\contentsline {subsection}{\numberline {8.2.1}CMAC}{36}%
\contentsline {subsection}{\numberline {8.2.2}CBC-MAC}{37}%