Cryptography Concepts and Terminology Cryptography Concepts - PowerPoint PPT Presentation

Cryptography Cryptography Concepts and Terminology Security Concepts Cryptography Concepts and Terminology Cryptography Concepts Cryptography Notation and Terminology Cryptography School of Engineering and Technology CQUniversity Australia Prepared by Steven Gordon on 21 Feb 2020, concepts.tex, r1808 1/11

Cryptography Contents Cryptography Concepts and Terminology Security Concepts Security Concepts Cryptography Concepts Cryptography Notation and Terminology Cryptography Concepts Cryptography Notation and Terminology 2/11

Cryptography Important Security Protections Cryptography Concepts and Terminology Confidentiality ensures only authorised parties can view information Security Concepts Cryptography Integrity ensures information, including identity of Concepts sender, is not altered Cryptography Notation and Availability ensures information accessible to authorised Terminology parties when needed 3/11

Cryptography Other Common Protections Cryptography Concepts and Terminology Authentication ensures that the individual is who she claims to be (the authentic or genuine person) and Security Concepts not an impostor Cryptography Concepts Authorisation providing permission or approval to use Cryptography Notation and specific technology resources Terminology Accounting provides tracking of events 4/11

Cryptography Scope Cryptography Concepts and Terminology ◮ Focus on confidentiality and integrity of information using technical means Security Concepts ◮ Means of authentication also covered Cryptography Concepts ◮ Accounting, system availability, policy, etc. are out of Cryptography Notation and scope Terminology ◮ See other subjects or books on “IT Security”, “Network Security Concepts” or similar 5/11

Cryptography Contents Cryptography Concepts and Terminology Security Concepts Security Concepts Cryptography Concepts Cryptography Notation and Terminology Cryptography Concepts Cryptography Notation and Terminology 6/11

Cryptography Encryption for Confidentiality Cryptography Concepts and Terminology ◮ Aim: assure confidential information not made available to unauthorised individuals (data confidentiality) Security Concepts ◮ How: encrypt the original data; anyone can see the Cryptography Concepts encrypted data, but only authorised individuals can Cryptography Notation and decrypt to see the original data Terminology ◮ Used for both sending data across network and storing data on a computer system 7/11

Cryptography Model of Encryption for Confidentiality Cryptography Concepts and Terminology Security Concepts Cryptography Concepts Cryptography Notation and Terminology 8/11

Cryptography Cryptography Terms Cryptography Concepts and Terminology Plaintext original message Security Concepts Ciphertext encrypted or coded message Cryptography Encryption convert from plaintext to ciphertext Concepts (enciphering) Cryptography Notation and Terminology Decryption restore the plaintext from ciphertext (deciphering) Key information used in cipher known only to sender/receiver Cipher a particular algorithm (cryptographic system) Cryptography study of algorithms used for encryption Cryptanalysis study of techniques for decryption without knowledge of plaintext Cryptology areas of cryptography and cryptanalysis 9/11

Cryptography Contents Cryptography Concepts and Terminology Security Concepts Security Concepts Cryptography Concepts Cryptography Notation and Terminology Cryptography Concepts Cryptography Notation and Terminology 10/11

Cryptography Common Symbols and Notation Cryptography Concepts and Symbol Description Example Terminology P Plaintext or message P = D( K AB , C ) Security Concepts M Message or plaintext M = D( PR B , C ) Cryptography C Ciphertext C = E( K AB , P ) Concepts C = E( PU B , M ) Cryptography Secret key, symmetric key K Notation and Terminology Secret key shared K AB between A and B E() Encrypt operation E( K AB , P ) E( PU B , M ) E cipher () Encrypt operation using E AES ( K AB , P ) named cipher D() Decrypt operation D( K AB , C ) D( PR B , C ) PU A Public key of user A PR A Private key of user A H() Hash operation H( M ) MAC() MAC operation MAC( K AB , M ) XOR, ⊕ Exclusive OR operation A XOR B , A ⊕ B h Hash value h = H( M ) || Concatenate (join) operation A || B 11/11