Security Issues in Networks with Internet Access
This paper can be considered as a good base for future work in the field of
security in internet. This paper discusses the security issues in a network with
internet access. It does not deal with the security problems in Internet as a whole.
But the work by the authors can be easily extended to the broad spectrum
of security issues in Internet.
The paper gives a set of rules that the networks should follow in order to make
sure that there will be no security breaches. It gives the example of a theoretical
networks that is integrated with internet in five stages, adding a new component
to the design in each stage. The major shortcomming of the analysis is that the
network considered is theoretical network. Such analysis cannot consider all the
problems associated with a practical network. The analysis will be directed
only towards the apparent problems in the network.
The authors say that the analysis of theoretical network is based on experience,
but do not specify what kind of experience. The analysis is not directed towards a
particular kind of network, but towards a general network. This is a drawback as
each network has its own set of security problems, all the rules mentioned may
not be applicable for a network. Therefore each kind of network has to be
analysed seperately to recognize all the problems associated with the network.
A comprehensive network security plan must encompass all the elements that
make up the network and provide important services like Authentication,
Confidentiality, Integrity and Non-repudiation. Also, this paper does not provide
technical details of encryption methods.
Inspite of above flaws paper serves as a good base for future work in this area. It
neatly classifies the various kinds of problems and threats associated with a
general network, and gives a direction to think to solves those problems.
Additional Information :
How to generate public and private keys using RSA ?
 Choose two large prime numbers, p,q and compute
n=pxq
 Randomly select an encryption key, e, such that the following are relatively
prime ( have no common factors other than 1) : e, (p – 1) x (q – 1)
 The decryption key is computed by solving the following d :
e x d = 1( mod (p –1) x (q –1) )
d = e –1 (mod (p –1) x (q –1) )
 Encrypt a message blocks m as shown :
c = me ( mod n)
 To Decrypt
m = cd ( mod n)
Example :
 Choose the primes p, q to be 47 and 71. Then
n = p x q = 3337
 Choose an encrypted key e and (p – 1) x (q –1) = 3220 have no common
factors other than 1 ( there are algorithms that do this ).
We’ll randomly pick e = 79
 We can now calculate the decrypted key d.
d = 79 –1 ( mod 3220) = 1019
The public key is (e,n) = (79, 3337)
The private key is d = 1019
 If we want to encrypt a block of message m = 688 ( assume it to be a part
of message) then,
688 79 (mod 3337) = 1570 = c
 To decrypt this cipher (c ),
1570 1019 (mod 3337) = 688 = m