tailieunhanh - Cryptography

Cryptography – science of encrypting information. “scrambles” data so only authorized parties can “unscramble” and read data Can substitute Can transpose Visual next slide | Security+ All-In-One Edition Chapter 4 – Cryptography Brian E. Brzezicki Cryptography Cryptography – science of encrypting information. “scrambles” data so only authorized parties can “unscramble” and read data Can substitute Can transpose Visual next slide Basic Idea Cryptographic Terminology Cryptography - a method of storing and transmitting data in a form only intended for authorized parties to read or process. Cryptanalysis* - science of studying, breaking, and reverse engineering algorithms and keys. (more) Cryptographic Terminology Encryption – the method of transforming data (plaintext) into an unreadable format. Plaintext – the format (usually readable) of data before being encrypted Cipher text – the “Scrambled” format of data after being encrypted (more) Cryptographic Terminology Decryption – the method of turning cipher text back into Encryption algorithm – a set or rules or procedures that dictates how to encrypt and decrypt data. Also called an encryption “cipher” Key – | Security+ All-In-One Edition Chapter 4 – Cryptography Brian E. Brzezicki Cryptography Cryptography – science of encrypting information. “scrambles” data so only authorized parties can “unscramble” and read data Can substitute Can transpose Visual next slide Basic Idea Cryptographic Terminology Cryptography - a method of storing and transmitting data in a form only intended for authorized parties to read or process. Cryptanalysis* - science of studying, breaking, and reverse engineering algorithms and keys. (more) Cryptographic Terminology Encryption – the method of transforming data (plaintext) into an unreadable format. Plaintext – the format (usually readable) of data before being encrypted Cipher text – the “Scrambled” format of data after being encrypted (more) Cryptographic Terminology Decryption – the method of turning cipher text back into Encryption algorithm – a set or rules or procedures that dictates how to encrypt and decrypt data. Also called an encryption “cipher” Key – (crypto variable) a values used in the encryption process to encrypt and decrypt (more) Cryptosystem Definitions (670) Key space – the range of possible values used to construct keys Key Clustering – Instance when two different keys generate the same cipher text from the same plaintext Work factor – estimated time and resources to break a cryptosystem Cryptography History Romans used a shift cipher called a “CEASAR” cipher. Shift Ciphers simply shift characters in an alphabet. (visual on next slide) ROT13 / shift cipher Go to to try Transposition Cipher Jumbles up the ordering of characters in a message. The Spartans of Greece used a form of this called the “Scytale” Cipher. (visual on next page) Scytale Vigenere Cipher Polyalphabetic Substitution Cipher – A more advanced substitution cipher as it any letter can have multiple letters substituted for it! That is an A will not always map to an N Harder to break! Visual next slide Vigenere Cipher Question So far which