Chapter 7: Cryptography Definitions and Concepts:

• Encryption is a method for transforming readable data (plaintext), into a form that appears to be random and unreadable (ciphertext).
• Cryptosystem is a system or product that provides encryption and decryption and it created through hardware components or program code in an application.
• The cryptosystem uses an encryption algorithm (which determines how simple or complex the encryption process will be), keys, and the necessary software components and protocols.
•  Most encryption methods use a secret value called key, which is a long string of bits, and works together with the algorithm to encrypt and decrypt the text.
• A Cryptosystems is made up of at least the following:
•  Software
• Protocols
•  Algorithms
• Keys
• Algorithm is a set of rules also known as the cipher, dictates how enciphering and deciphering takes place.
• The Key (cryptovariable) is a value that can comprises a large sequence of random bits.
• The Keyspace is a range of values that can be used to construct a key.
• The larger the keyspace, the more available values can be used to represent different keys, this will provide for a more random set of keys and it will be harder for intruders to figure them out.

Kerckhoff’s Principle

Auguste Kerckhoff, published a paper in 1883

• States that only secrecy involved with cryptography systems should be the key and the algorithms should be publicly known.
• Argument:
• If an algorithm is publicly known more people can view the source code, test it, and uncover any type of flaws or weaknesses, then the developers can fix it.
• Government's Argument:
• If smaller number of people know how the algorithm actually works, then a smaller number of people will know how to possibly break it.