encryption and compression

Reduces the size of a data file Uses less storage Faster download

Lossy compression maximises the reduction in file size But there may be a loss of quality Store fewer data points Store using simpler code numbers Sounds will be sampled less often pre seconds and recorded with less precision Images will be low resolution and low colour depth

Sometimes possible to compress data with no loss of data quality, but the reduction in size may be less Run-length encoding Dictionary compression (colour palette)

Encrypting a message means disguise it so it can’t be read by anyone who doesn’t have the key Decrypting means returning an encrypted message to readable form Necessary to keep personal and financial details safe when sending over the internet

The same key is used to encrypt and decrypt