Exchanging data and encryption

To reduce the amount of data to send or store Benefits: -Data is sent more quickly -less storage is required

-Lossy - non essential data is permanetly removed -lossless- Patterns in the data are spotted and summerized in a shorter format ; without permanetly removing any information

-RLE (Run length Encoding) A basic method of compression that summerises consecutive patterns of the same data -Dictionary Compression Spots reguarly Occuring data and stores it seperatly in a dictionary

A way of making sure data cannot be understood , if you dont possess the means to decrypt

the Caesar cipher is the most basic type of encryption and the most insecure

Tries all the possible combinations to attempt to decrypt ciphertext until one works

letters are not used equally often

• Vernham cipher is the most secure type of encrpytion , this generates an OTP that is unique ADV: -most secure encryption dis-adv: -true random number is diffucult to acheive -the key mus be shared secretly -they key must be as long as text

• An entitiy is a category of object, person, event to thing of intrest about which data needs to be recorded

primary key - is a unique identifier for each record in a table secondary key - allows a database to be searched quickly foreign key - a foreign key is the attribute which links two tables together

a composite primary key is two or more primary keys in a table

• one to one = husband to wife • one to many = mother to kids • many to many = actor to films

Lossy: - Audio -Images -video Lossless: -Documents -files

The role of asymmertic information works is that both the sender and receiver have a public key, which is used to encrypt the data, both public keys are available to both parties, an accessible by anyone. Then a private key, which is used to decrypt the data, is only available to the specific recipient,

a Public key is a key that is used to encrypt data( this is avaliable to anyone , and is sent to the receiver) a private key is a key that is used to dycrpt data( the recipient only has access to there own private key)

This uses the same private key to encrypt an decrypt data , the keys are are transferred which makes it easy to be intercepted

HTTP- requesting webpages IMAP- email protocol, designed to keep emails on a server FTP- used to transfer files DHCP- dynamic host configuration protocol SMTP- used to transfer outgoing emails POP3- responsible for retrieving emails, from a mail server that temporarily stores incoming mail