• What is cryptography ?• Why cryptography is important ?
Contents• The purpose of cryptography• History of cryptography and cryptanalysis• Modern cryptography(Types of Algorithms) - Secret Key Cryptography - Hash Functions - Public Key Cryptography - Why Three Encryption Techniques? - The Significance of Passwords & Password Security• Conclusion
THE PURPOSE OF CRYPTOGRAPHYSpecific security requirements for communication: Data transfer and telecommunication Science of communications code Computer writing in secret Authentication: Privacy/confidentiality: Integrity: Non-repudiation:
HISTORY OF CRYPTOGRAPHYThe history of cryptography can be divided into twoparts:(1) From ancient civilizations to the 19th century and thefirst part of the 20th century,(2) Use of encrypting electro-mechanicalmachines, around the period of the WW II.
HISTORY OF CRYPTOGRAPHYCryptography was used in three kinds of contexts inCryptography::ancient times Private communicationsGreek κρυπτός, kryptos, Art and religion"hidden, secret" Military and diplomatic use
MODERN CRYPTOGHRAPHYHere we have three types of algorithms that we cantalk about: Secret Key Cryptography Hash Functions Public Key Cryptography
SECRET KEY CRYPTOGHRAPHY Secret Key(Symmetric) Cryptography uses a single key for both encryption and decryption.
SECRET KEY CRYPTOGHRAPHY A single key is used Sender uses the key to encrypt Receiver uses the same key to decrypt Key must be known to both the sender and the receiver The difficulty is the distribution of the key
SECRET KEY CRYPTOGHRAPHYSecret key cryptography algorithms that are in usetoday : Data Encryption Standard (DES): Advanced Encryption Standard (AES): International Data Encryption Algorithm (IDEA):