ECES exam 2023 with 100% correct answers

What is cryptography? Noun - A) The process or skill of communicating in or deciphering secret writings or ciphers B) Secret writing Origin - Cryptography (or cryptology); derived from word kryptos which means "hidden", and grafo, which means "write", is the study of message secrecy Definition- Cryptography is the science of altering communication so that it cannot be understood without having the key Interloper a person who becomes involved in a place or situation where they are not wanted or are considered not to belong. History of cryptography A) Hidden or secret writing is very old: People have been practicing hidden writing for at least 3,000 years. B) Until the latter part of the 20th century, cryptography was almost exclusively used by military and government Mono-Alphabetic Substitution A) Most primitive cryptographic algorithms B) Substitute one character of cipher text for each character of plain text C) Caesar Cipher, Atbash Cipher, Affine Cipher, Rot13 Cipher Caesar Cipher A) First used by Julius Caesar B) Every letter is shifted a fixed number of spaces to the left or the right in the alphabet C) The shifting is the "key" for this algorithm D) The shift is often called the "alphabet" being used. Example "I Like Computers" shift 1 to left becomes "H Khjd Bnlotsdqr" *Most common single-letter word is "A" and most common three-letter word is "the". Most common two-letter combinations are "EE" and "OO"* E) 128-bit number from AES (Advanced Encryption Standard)