Unit 4 Exchanging Data

• Lossy • Lossless

Removing non-essential data

Summarizing patterns in the data without permanently removing any data

A basic method of coding that summarizes consecutive patterns of the same data

Image and sound data

Spots regularly occurring data and stores it separately in a dictionary

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A way of making sure that data cant be read without a way to decrypt it

A type of encryption where letters of the alphabet are shifted by a constant amount

A method that attempts to apply every possible key to decrypt ciphertext until one works

A method that looks at the most frequent characters in cypher text and comparing them to regular text

A type of encryption, also know as the one-time pad. It is the only cypher text that is proven to be unbreakable

• Must be truly random • Must be greater or equal to the length of the plaintext • Must only be used once • Must be shared by hand separate to the original message • Must be destroyed immediately after use

Also known as private key encryption, the same key is used to encrypt and decrypt

A type of encryption that uses 2 keys. One key (public key) is made public so that others can encrypt data before sending it to you. Another key (private key) is only known to you and can be used to decrypt the data

A type of encryption that is one-way and cannot go back to the original. Useful for storing encrypted PINs

A flat file consisting of information about a single entity

A category of object, person, event or thing of interest about which data needs to be recorded

A name which uniquely identifies a particular record (also known as primary key)

Where 2 or more attributes are needed to uniquely define a record

• One to one • One to many • Many to many

An attribute that creates a join between 2 tables (relations)

Where no foreign key can reference a record that doesn’t exist in another table

No, an extra table is required