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9 questions
What are the key reasons for compressing data?
Less space needed for storage
Less time to transmit
Higher quality files
Reduced amount of processing power
Limited RAM
Lossless compression...
Is used when not all the information is needed
Is not as effective as lossy compression
Can fully regenerate the original file
Includes files such as .ZIP
Would be a sensible choice for a music download site
Lossy compression...
Permanently removes data from a file
Always leads to a noticeable loss of quality
Aims to remove redundant data
Can return the original file to its original quality
Would be a sensible choice for a music download site.`
Dictionary based compression...
Is a lossless compression format
Creates a dictionary of common letter combinations to encode words with fewer characters
Creates a dictionary of smaller letters so less space is used
Sends the dictionary with the data
Doesn't need to send the dictionary with the data
Run-length encoding...
is Lossless
is Lossy
Can only be used for text
Records the number of repeats of an individual element
Can be used for a wide variety of file types
Encryption...
Uses at least one key to cipher data
Is only used on text
Can be symmetric or asymmetric
Is impossible to break
Has developed a lot as processing power has increased
Symmetrical encryption techniques...
Are the most secure types of encryption
Use a single key to encode/decode
Use multiple keys to encode/decode
Include XOR, Caesar and Route
Include RSA, Diffie-Hellman and DSS
Asymmetrical encryption techniques...
Are the most secure types of encryption
Use a single key to encode/decode
Use multiple keys to encode/decode
Include XOR, Caesar and Route
Include RSA, Diffie-Hellman and DSS
Asymmetrical encryption...
Often requires considerable processing power
Is impossible to break
Is being threatened by the possibility of quantum computing
Can be brute-force attacked
Is very widely used, even in small businesses
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