Outline of cryptography

Essence of cryptography

• Cryptographer
• decryption
• Cryptographic key
• Cipher
• Ciphertext
• Plaintext
• Code
• Tabula recta
• Alice and Bob

Uses of cryptographic techniques

• Commitment schemes
• Secure multiparty computation
• Electronic voting
• Authentication
• Digital signatures
• Crypto systems
• Dining cryptographers problem
• Anonymous remailer
• Pseudonymity
• Onion routing
• Digital currency
• Secret sharing
• Indistinguishability obfuscation

Branches of cryptography

• Multivariate cryptography
• Post-quantum cryptography
• Quantum cryptography
• Steganography
• Visual cryptography

History of cryptography

• Japanese cryptology from the 1500s to Meiji
• World War I cryptography
• World War II cryptography
  • Reservehandverfahren
  • Venona project
  • Ultra

Ciphers

Classical

Substitution

• Monoalphabetic substitution
  • Caesar cipher
    • ROT13
  • Affine cipher
  • Atbash cipher
  • Keyword cipher
• Polyalphabetic substitution
  • Vigenère cipher
  • Autokey cipher
  • Homophonic substitution cipher
• Polygraphic substitution
  • Playfair cipher
  • Hill cipher

Transposition

• Scytale
• Grille
• Permutation cipher
• VIC cipher – complex hand cypher used by at least one Soviet spy in the early 1950s; it proved quite secure for the time

Modern symmetric-key algorithms

Stream ciphers

• A5/1 & A5/2 – ciphers specified for the GSM cellular telephone standard
• BMGL
• Chameleon
• FISH – by Siemens AG
• WWII 'Fish' cyphers
  • STURGEON by Bletchley Park
  • Pike – improvement on FISH by Ross Anderson
  • Schlusselzusatz – WWII mechanical onetime pad by Lorenz, called tunny by Bletchley Park
• HELIX
• ISAAC – intended as a PRNG
• Leviathan
• LILI-128
• MUGI – CRYPTREC recommendation
• MULTI-S01 - CRYPTREC recommendation
• One-time pad – Vernam and Mauborgne, patented 1919; an extreme stream cypher
• Panama
• MIT; CRYPTREC
  recommended limited to 128-bit key
  • RC4 variant with 10 byte random IV
    , easy to implement
• Salsa20 – an eSTREAM recommended cipher
  • ChaCha20
    – A Salsa20 variant.
• SEAL
• SNOW
• SOBER
  • SOBER-t16
  • SOBER-t32
• WAKE

Block ciphers

• Product cipher
• Feistel cipher – pattern by Horst Feistel
• NIST selection for the AES, FIPS 197; Created 2001—by Joan Daemen and Vincent Rijmen; NESSIE selection; CRYPTREC
  recommendation.
• Anubis – 128-bit block
• BEAR – built from a stream cypher and hash function, by Ross Anderson
• Blowfish – 64-bit block; by Bruce Schneier et al.
• Camellia – 128-bit block; NESSIE selection (NTT & Mitsubishi Electric); CRYPTREC recommendation
• CAST5) – 64-bit block; one of a series of algorithms by Carlisle Adams and Stafford Tavares
  , insistent that the name is not due to their initials
  • CAST6
    ) – 128-bit block; the successor to CAST-128 and a candidate for the AES competition
• CIPHERUNICORN-A – 128-bit block; CRYPTREC recommendation
• CIPHERUNICORN-E – 64-bit block; CRYPTREC recommendation (limited)
• CMEA
  – cipher used in US cellphones, found to have weaknesses.
• CS-Cipher – 64-bit block
• Data Encryption Standard (DES) – 64-bit block; FIPS 46-3, 1976
• DEAL – an AES candidate derived from DES
• DES-X – a variant of DES to increase the key size.
• FEAL
• GDES – a DES variant designed to speed up encryption
• Grand Cru – 128-bit block
• Hierocrypt-3 – 128-bit block; CRYPTREC
  recommendation
• Hierocrypt-L1 – 64-bit block; CRYPTREC
  recommendation (limited)
• IDEA NXT – project name FOX, 64-bit and 128-bit block family; Mediacrypt (Switzerland); by Pascal Junod & Serge Vaudenay of Swiss Institute of Technology Lausanne
• ETH
  Zurich
• Iraqi Block Cipher
  (IBC)
• cellular phone
  security
• KHAZAD – 64-bit block designed by Barretto and Rijmen
• Khufu and Khafre – 64-bit block ciphers
• Kuznyechik – Russian 128-bit block cipher, defined in GOST R 34.12-2015 and RFC 7801.
• LION – block cypher built from stream cypher and hash function, by Ross Anderson
• LOKI89/91 – 64-bit block ciphers
• LOKI97 – 128-bit block cipher, AES candidate
• NSA/NBS and released as DES
• MAGENTA – AES candidate
• Mars – AES finalist, by Don Coppersmith
  et al.
• MISTY1 – NESSIE selection 64-bit block; Mitsubishi Electric (Japan); CRYPTREC recommendation (limited)
• MISTY2 – 128-bit block: Mitsubishi Electric (Japan)
• Nimbus – 64-bit block
• NOEKEON – 128-bit block
• NUSH – variable block length (64-256-bit)
• Q – 128-bit block
• RC2 – 64-bit block, variable key length
  • RC6 – variable block length; AES finalist, by Ron Rivest et al.
  • RC5 – Ron Rivest
• SAFER – variable block length
• SC2000 – 128-bit block; CRYPTREC recommendation
• Lars Knudsen
• SHACAL-1
  – 160-bit block
• SHACAL-2 – 256-bit block cypher; NESSIE
  selection Gemplus (France)
• Rijndael/AES
  , by Daemen and Rijmen
  • Rijndael/AES
    , by Daemen and Rijmen
• TEA – by David Wheeler & Roger Needham
• Triple DES – by Walter Tuchman, leader of the Lucifer design team—not all triple uses of DES increase security, Tuchman's does; CRYPTREC recommendation (limited), only when used as in FIPS Pub 46-3
• Twofish – 128-bit block; AES finalist by Bruce Schneier et al.
• XTEA – by David Wheeler & Roger Needham
• 3-Way – 96-bit block by Joan Daemen
• Polyalphabetic substitution machine cyphers
  • Enigma
    – WWII German rotor cypher machine—many variants, any user networks for most of the variants
  • Purple
    – highest security WWII Japanese Foreign Office cypher machine; by Japanese Navy Captain
  • William Friedman, Frank Rowlett
    et al.
  • TypeX
    – WWII UK cypher machine
• Hybrid code/cypher combinations
  • JN-25
    – WWII Japanese Navy superencyphered code; many variants
  • Naval Cypher 3 – superencrypted code used by the Royal Navy in the 1930s and into WWII

Modern asymmetric-key algorithms

Asymmetric key algorithm

• ACE-KEM – NESSIE selection asymmetric encryption scheme; IBM Zurich Research
  • ACE Encrypt
• Chor-Rivest
• Diffie-Hellman – key agreement; CRYPTREC
  recommendation
• El Gamal
  – discrete logarithm
• Elliptic curve cryptography
  – (discrete logarithm variant)
• PSEC-KEM – NESSIE selection asymmetric encryption scheme; NTT (Japan); CRYPTREC recommendation only in DEM construction w/SEC1 parameters
  • ECIES
    – Elliptic Curve Integrated Encryption System, Certicom Corporation
  • ECIES-KEM
  • ECDH – Elliptic Curve Diffie-Hellman key agreement, CRYPTREC
    recommendation
• EPOC
• Kyber
• Merkle–Hellman knapsack cryptosystem – knapsack scheme
• McEliece cryptosystem
• Niederreiter cryptosystem
• NTRUEncrypt
• RSA
  – factoring
  • RSA-KEM – NESSIE selection asymmetric encryption scheme; ISO/IEC 18033-2 draft
  • RSA-OAEP – CRYPTREC
    recommendation
• Rabin cryptosystem – factoring
  • Rabin-SAEP
  • HIME(R)
• Paillier cryptosystem
• Threshold cryptosystem
• XTR

Keys

Key authentication

• Public key infrastructure
  • X.509
  • OpenPGP
• Public key certificate
  • Certificate authority
  • Certificate revocation
• ID-based cryptography
• Certificate-based encryption
• Secure key issuing cryptography
• Certificateless cryptography
• Merkle tree

Transport/exchange

• Diffie–Hellman
• Man-in-the-middle attack
• Needham–Schroeder
• Offline private key
• Otway–Rees
• Trusted paper key
• Wide Mouth Frog

Weak keys

• Brute force attack
• Dictionary attack
• Related key attack
• Key derivation function
• Key strengthening
• Password
• Password-authenticated key agreement
• Passphrase
• Salt
• Factorization^[1]

Cryptographic hash functions

• Message authentication code
• Keyed-hash message authentication code
  • Encrypted CBC-MAC (EMAC) – NESSIE selection MAC
  • FIPS PUB 113 and IETF RFC
  • TTMAC – (Two-Track-MAC) NESSIE selection MAC; K.U.Leuven (Belgium) & debis AG (Germany)
  • UMAC – NESSIE selection MAC; Intel, UNevada Reno, IBM, Technion, & UC Davis
  • Oblivious Pseudorandom Function
• MD5 – one of a series of message digest algorithms by Prof Ron Rivest of MIT; 128-bit digest
• NSA 160-bit digest, an FIPS standard; the first released version was defective and replaced by this; NIST/NSA have released several variants with longer 'digest' lengths; CRYPTREC
  recommendation (limited)
  • SHA-256 – NESSIE selection hash function, FIPS 180-2, 256-bit digest; CRYPTREC
    recommendation
  • SHA-384 – NESSIE selection hash function, FIPS 180-2, 384-bit digest; CRYPTREC
    recommendation
  • SHA-512 – NESSIE selection hash function, FIPS 180-2, 512-bit digest; CRYPTREC
    recommendation
• SHA-3 – originally known as Keccak; was the winner of the NIST hash function competition using sponge function.
• Streebog – Russian algorithm created to replace an obsolete GOST hash function defined in obsolete standard GOST R 34.11-94.
• RIPEMD-160 – developed in Europe for the RIPE project, 160-bit digest; CRYPTREC
  recommendation (limited)
• RTR0 – one of Retter series; developed by Maciej A. Czyzewski; 160-bit digest
• Tiger – by Ross Anderson et al.
• Snefru
  – NIST hash function competition
• Whirlpool – NESSIE
  selection hash function, Scopus Tecnologia S.A. (Brazil) & K.U.Leuven (Belgium)

Cryptanalysis

Classical

• Frequency analysis
• Contact analysis
• Index of coincidence
• Kasiski examination

Modern

• Symmetric algorithms
  • Boomerang attack
  • Brute force attack
  • Davies' attack
    ;
  • Differential cryptanalysis
  • Impossible differential cryptanalysis
  • Integral cryptanalysis
  • Linear cryptanalysis
  • Meet-in-the-middle attack
  • Mod-n cryptanalysis
  • Related-key attack
  • Slide attack
  • XSL attack
• Hash functions:
  • Birthday attack
• Attack models
  • Chosen-ciphertext
  • Chosen-plaintext
  • Ciphertext-only
  • Known-plaintext
• Side channel attacks
  • Power analysis
  • Timing attack
  • Cold boot attack
• Network attacks
  • Man-in-the-middle attack
  • Replay attack
• External attacks
  • Black-bag cryptanalysis
  • Rubber-hose cryptanalysis

Robustness properties

• Provable security
• Random oracle model
• Ciphertext indistinguishability
• Semantic security
• Malleability
• Forward secrecy
• Forward anonymity
• Freshness

Undeciphered historical codes and ciphers

• Beale ciphers
• Chaocipher
• D'Agapeyeff cipher
• Dorabella cipher
• Rongorongo
• Shugborough inscription
• Voynich manuscript

Organizations and selection projects

Cryptography standards

• NIST
  to produce standards in many areas to guide operations of the US Federal government; many FIPS publications are ongoing and related to cryptography
• American National Standards Institute (ANSI) – standardization process that produces many standards in many areas; some are cryptography related, ongoing)
• International Organization for Standardization (ISO) – standardization process produces many standards in many areas; some are cryptography related, ongoing
• Institute of Electrical and Electronics Engineers (IEEE) – standardization process produces many standards in many areas; some are cryptography related, ongoing
• Internet Engineering Task Force (IETF) – standardization process that produces many standards called RFCs) in many areas; some are cryptography related, ongoing)

General cryptographic

• National Security Agency (NSA) – internal evaluation/selections, charged with assisting NIST in its cryptographic responsibilities
• Government Communications Headquarters
  (GCHQ) – internal evaluation/selections, a division is charged with developing and recommending cryptographic standards for the UK government
• SIGINT agency, part of ECHELON
• Communications Security Establishment (CSE) – Canadian intelligence agency

Open efforts

• NBS
  selection process, ended 1976
• RIPE – division of the RACE project sponsored by the European Union, ended mid-1980s
• NIST
  , ended in 2001
• NESSIE Project – an evaluation/selection program sponsored by the European Union, ended in 2002
• eSTREAM– program funded by ECRYPT; motivated by the failure of all of the stream ciphers submitted to NESSIE, ended in 2008
• CRYPTREC – evaluation/recommendation program sponsored by the Japanese government; draft recommendations published 2003
• CrypTool – an e-learning freeware programme in English and German— exhaustive educational tool about cryptography and cryptanalysis

Influential cryptographers

List of cryptographers

Legal issues

• AACS encryption key controversy
• Free speech
  • Bernstein v. United States - Daniel J. Bernstein's challenge to the restrictions on the export of cryptography from the United States.
  • Junger v. Daley
  • DeCSS
  • Phil Zimmermann - Arms Export Control Act investigation regarding the PGP software.
• Export of cryptography
• Clipper Chip
• Digital Millennium Copyright Act
• Digital Rights Management
  (DRM)
• Patents
  • RSA
    – now public domain
  • David Chaum – and digital cash
• Cryptography and law enforcement
  • Telephone wiretapping
  • Espionage
• Cryptography laws in different nations
  • Official Secrets Act – United Kingdom, India, Ireland, Malaysia, and formerly New Zealand
  • Regulation of Investigatory Powers Act 2000 – United Kingdom

Academic and professional publications

• Journal of Cryptology
• Encyclopedia of Cryptography and Security
• Cryptologia – quarterly journal focusing on historical aspects
• Communication Theory of Secrecy Systems – cryptography from the viewpoint of information theory

Allied sciences

• Security engineering

See also

• Outline of computer science
• Outline of computer security

References