Custom essays on Stallings

1 Stallings illustrates four ways in which plaintext can be transmitted with message authentication. Compare and contrast these four ways of message authentication
Stallings focuses on four ways plain text can be transmitted with message authentication. First, Stalligns distinguishes authentication using private-key ciphers, which means the data transition with the unique key, with the help of which a user can get access to the information sent. Second, hashing functions are used to cipher the message and, as a rule, to be accompanied with the digital signature. Digital signature schemes comprise another way of transmitting data and message authentication. The digital signature schemes allow controlling sending and delivering the message without changes. Finally, Stallings suggests using authentication protocols which actually control and regulate the message authentication. Authentication protocols are complex structures that control and test the authenticity of messages.
2 Hash functions (such as SHA-1) were not designed to be used as Message Authentication Codes (MACs) and cannot be used directly for that purpose because they do not rely on a secret key. Explain.
In fact, Hash functions are considered to be public and they are different from the authentication codes and keys. As the matter of fact, they do not have a key, although often they are used in a combination with a digital signature. The main function of hash functions is to convert a large amount of information and cipher it to transmit from a sender to a receiver. At the same time, hash functions divide a large amount of data into small pieces of information, which are easy to transmit and to cipher. As a result, hash functions send small pieces of information and the receiver can obtain all the information sent, when all the pieces of information being divided by hash functions are received. In such a way, hash functions do not use any key. On the other hand, they can match keys to send the information to a particular receiver. In such a way, hash functions contribute to relatively secure transmitting of data.
3 What is a digital signature?
A digital signature is an effective tool used to protect the information transmitted online or from one electronic device to another. In its essence, a digital signature is a mathematical scheme for demonstrating authenticity of the digital message or document.
a. How is it like and unlike, a pen-and-paper signature (or isn’t this a fair question)?
Basically, digital signature performs the same functions as a pen-and-paper signature but it is applied to digital messages and documents solely. Unlike a pen-and-paper signature, a digital signature does not contain a sample of writing of a sender of information but it just comprises a mathematical scheme attributed to a particular sender of information.
b. What are digital signatures used for?
Digital signatures are used for transmitting digital documents and messages. The main point of using digital signatures is to prove that a message was created by a known person and that it was not altered in the course of transit. In such a way, senders can be certain that receivers will receive the information unaltered.
c. What are the threats to digital signatures?
The main threats to digital signature are grounded on information breaches and the risk of eavesdropping of digital signatures by third parties that may lead to the misuse of digital signatures.

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