Cryptography – science of encrypting information. “scrambles” data so only authorized parties can “unscramble” and read data using two methods Can substitute – change one letter with a different letter Can transpose – scramble the order of letters, without actually changing one for another. The best cryptosystems both substitute and transpose. Visual next slide | Security+ All-In-One Edition Chapter 4 – Cryptography Brian E. Brzezicki Cryptography (77) Cryptography – science of encrypting information. “scrambles” data so only authorized parties can “unscramble” and read data using two methods Can substitute – change one letter with a different letter Can transpose – scramble the order of letters, without actually changing one for another. The best cryptosystems both substitute and transpose. Visual next slide Basic Idea Cryptographic Terminology (77) 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 (n/b) 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 . | Security+ All-In-One Edition Chapter 4 – Cryptography Brian E. Brzezicki Cryptography (77) Cryptography – science of encrypting information. “scrambles” data so only authorized parties can “unscramble” and read data using two methods Can substitute – change one letter with a different letter Can transpose – scramble the order of letters, without actually changing one for another. The best cryptosystems both substitute and transpose. Visual next slide Basic Idea Cryptographic Terminology (77) 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 (n/b) 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 (n/b) 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) (n/b) Key space – the range of possible values used to construct keys example: if a key can be 4 digits (0-9) key space = 10,000 (0000 – 9999) if it can be 6 digits key space = 1,000,000 (000,000 – 999,999) 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 (78) 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 .
