Encryption exercises


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Exercise

·	Decode the following message: (time yourself)

                       GNV DZYX HR SGHR.


·	What is your password

Y P W I
O A O S
U S R 5
R S D 3

·	Using your password decode the message below.

                    A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
  		
		OKZ PJUZ  BJX YR OKZ IVVOHM TRP BHO
·	Name some of the types of unknown people who
 have access to the computers and networks
 of others.

·	Where is a safe place to hide your password.
 For that matter name 10 different safe places
 to hide your password and why they would work.

·	What's all the fuss about, why do we need secured data.
Give four examples of where data has to be secured.







Encryption of data.

When data is stored or transferred between computers it can be
 read by others.  The data on your hard disk is not secure.
  Just knowing which file contains the passwords can make
 it easier for the hackers.

Any data that has a fixed pattern, or rigid format will also make it
 easier for hackers.  

The solution is to encrypt everything, and to use huge 
passwords and complex encryption algorithms to do the encryption.  

This has five effects. 
·	It requires every piece of data to be encrypted.
·	The encryption must take place at the source.
·	Each time the data is used it has to be de-Encrypted.
·	And what happens to temporary system files that are 
used for recovery, at some stage they will contain 
un-encrypted 
data. Even screen buffers hold unencrypted data.

·	There has to be a second password file that can be 
accessed by the systems administrator in the event that you 
forgot or lost your password, otherwise the files would be 
lost forever.

Problem - too  much encryption.

The time it takes to encrypt and de-encrypt data can become an 
issue, and if large data files are involved or there are huge transaction
 volumes the elapsed time can be unacceptable.
  And if rapid response times are needed then the problem is compounded.
  The solution is to increase the processing power of your 
computers and to spread the load across the network.