ESOC 477: Cryptography Part I

If the two bits are identical the result is?

A binary 0

If the two bits are not identical, the result is?

A binary 1

Exclusive OR (XOR)

A function within Boolean algebra used as an encryption function in which two bits are compared

Developed to replace both DES and 3DES

Advanced Encryption Standard (AES)

If either copy of the key is compromised in a symmetric encryption what happens?

An intermediate can decrypt and read messages without sender/receiver knowledge

A cryptographic method that incorporates mathematical operations involving two different keys (commonly known as the public key and the private key) to encipher or decipher a message

Asymmetric Encryption

Also known as public-key encryption

Asymmetric Encryption

Each plaintext bit is transformed into a cipher bit one bit at a time

Bit Stream

Plain-text can be encrypted through two methods (2)

Bit Stream & Block Cipher

Message is divided into blocks (e.g., sets of 8- or 16-bit blocks), and each is transformed into encrypted block of cipher bits using algorithm and key

Block Cipher

Ciphertext consists of a list of codes representing page, line, and word numbers of plaintext word

Book Cipher

In symmetric encryption, both sender and receiver must possess this

Both sender and receiver must possess the same secret key

Transposition cipher can be done on what level(s)?

Can be done at the bit level or at the byte (character) level

The process of obtaining the plaintext message from a ciphertext message without knowing the keys used to perform the encryption

Cryptanalysis

The process of making and using codes to secure information

Cryptography

The field of science that encompasses cryptography and cryptanalysis

Cryptology

One of the most popular symmetric encryption cryptosystems

Data Encryption Standard (DES)

How does asymmetric encryption work?

Either key can be used to encrypt a message, but then the other key is required to decrypt it

All popular Web browsers use built-in what?

Encryption features for secure e-commerce applications

Mathematical algorithms that create a message summary or digest to confirm message identity and integrity

Hash Functions

Used in password verification systems to store passwords and confirm the identity of the user

Hash Functions

Only incorporates a single alphabet in the encryption process

Mono-alphabetic substitution

Transposition Cipher is also known as?

Permutation cipher

Incorporates two or more alphabets in the encryption process

Polyalphabetic substitution

Was the first public-key encryption algorithm developed/published for commercial use

RSA algorithm (1977

Uses a book for passing the key to cipher similar to Vigenère cipher; sender provides encrypted message with sequence of numbers from predetermined book to be used as an indicator block

Running key cipher

Substitutes or exchanges one value for another

Substitution Cipher

A cryptographic method in which the same algorithm and "secret" are used both to encipher and decipher the message; also known as private-key encryption

Symmetric Encryption

Cryptographic Algorithms are Often grouped into two broad categories

Symmetric and Asymmetric

Involves use of hidden message in book, letter, or other message; requires page with a specific number of holes cut into it.

Template cipher

How can one make the encryption even stronger?

The keys and block sizes can be increased to 128 bits or more

Symmetric and asymmetric algorithms are distinguished by what?

The types of keys used for encryption and decryption operations

You should NEVER use Exclusive OR (XOR) with?

Transmitting/storing sensitive data

Involves simply rearranging the values within a block based on an established pattern

Transposition Cipher

Created to provide security far beyond DES

Triple DES (3DES)

A cryptographic technique developed at AT&T and known as the "one-time pad

Vernam Cipher

This cipher uses a set of characters for encryption operations only one time and then discards it

Vernam Cipher

The problem with Exclusive OR (XOR)?

Very simple to implement and simple to break; should not be used by itself when organization is transmitting/storing sensitive data

Advanced type of substitution cipher that uses a simple polyalphabetic code; made up of 26 distinct cipher alphabets

Vigenère cipher

Today's popular cryptosystems use a combination of?

symmetric and asymmetric algorithms