In recent years, computer programmers have tried to make it easy for people to use computer systems. Unfortunately, in some situations the systems are too easy to use; they don’t have enough restrictions to safeguard secret information or to prevent an unauthorized person  from using that information. Therefore, several methods have been devised to prevent computer crime.

Decryption and Encryption
Encryption and Decryption

One of them is data encryptation. When secret personal and financial data is transmitted to and from remote terminals, it must be encrypted (translated into a secret code) at one end and decrypted (translated back into plain text) at the other. Since it is impractical to keep secret the algorithms that are used to encrypt and decrypt data, these algorithms are designed so that their operation depends on a certain data item called the key.


It is the key that is kept secret. Even if you know all the details of the encrypting and decrypting algorithms, you cannot decrypt any messages unless  you know the key that was used when they were encrypted. For instance, the National Bureau of Standards has adopted an algorithm for encrypting and decrypting the data processed by federal agencies.

Providing Data
Data Provider

The details of the algorithm have been published in the Federal Register. Plans are under way to incorporate the algorithm in special  purpose microprocessors, which anyone can purchase and install in his computer. So the algorithm is available to anyone who bothers to buy one of the special purpose microprocessors. But the operation of the algorithm is governed by a sixty-four-bit key.

Since there are about 10,000,000,000,000,000,000,000 possible sixty-four-bit keys, no one  is likely to discover the correct one by chance. And, without the correct key, knowing the algorithm is useless.

Standards of  Data Encryption
Data Encryption Standards


Mark the best choice.

1. Line 4, ‘an unauthorized person’ means a person who .

a) has no official permission to do something

b) has no right to restrict or control others

c) doesn’t know anything about the subject

d) doesn’t know how to write something


2. One can decrypt messages only if he knows .

a) all the details of the encrypting and decrypting algorithms

b) the key used while the messages were encrypted

c) that algorithms are used to encrypt and decrypt data

d) that the key is kept secret for security measures

3. The algorithm adopted by the National Bureau of Standards can only be used if a person .

a) reads the details of the algorithm in the Federal Register

b) incorporates the algorithm in special purpose microprocessors

c) knows the algorithm

d) buys a special purpose microprocessor
4. As the operation of the algorithm is governed by any one of the 10,000,000,000,000,000,000,000 possible sixty-four-bit keys

. a) one can discover it only by chance

b) discovering it by chance is not possible

c) one should know the algorithm

d) no one can get the correct key


The invention orders

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