Some comparison on application of cryptology algorithms

In this article we are going to compare useful cryptology algorithm in different area and explain them though application of algorithms have very large area but doing some comparison one can do decision of usage of introduced algorithm in right place. In this article first we mention important point of, digital signature and distribution key and then we compare these tow cryptology algorithms


Key Distribution and key Agreement
In comparison of Public key system and private key system we know that public key is better since public key does not need safe channel and exchange of keys .But Public key system is acting slower than for that reason for long massage usually use private key system like DES in the following we explain methods which reduces these weakness .

Key Distribution of BLOM
 We make prime P and for each user U let u  ,  If u ,v decided to contact they use common key [1] , ,

Diffe-Hellman Distribution key
We explain only algorithm  We P is prime and p Z    will be made as public. This problem known as Diffe _Hellman Problem.
Since problem of Disconnected logarithm is difficult in p Z so this Distribution key of Diffe-Hellman is safe. The point is here that how much this system is safe? We cannot say but we can do some comparison.
Theorem: Breaking of cryptology system of EL Gamal is equal of Diffe-Helman.[2]

Kerberos
Having a key for long time is dangerous so in this system on line will be produced by TA and time L will be considered after time L new key will be produced by TA. follow the algorithm.
 U ask a session key from TA for contact V .  TA choose a random session key and also a time stamp T and a time line L.  TAcalculate following values:

Exchange of key (Diffe-Hellamn)
If we van not useon line production of key we use this method.

Digital signature
Another application of cryptology algorithm is to use in digital signature in this section we explain different system of cryptology which will be used in digital signature. First of all we explain a general procedure for signature then in other sections we explain different use of algorithm in signature system. [5] A system of signature is a quandary (P, A, K.S, V) which satisfy following conditions.
 P a finite set of possible message.  A a finite set of signature.  K a finite set of keys. , x P y A  ,is called message signature. Now we consider different system of signature.

System of RSA signature
Consider n=pq which p and q are prime such that . Different attack for this system are as follow:  key-only attack  Known massage attack  chosen message attack  Total break  selective forgery  existential forgery

System of Hash function signature
Usually in systems of signatures there is fast hash function of public cryptology. System signature with hash function is as follow: You can see that hash function and use of short message make safe system.

El Gamal system of signature
El Gamal introduced on 1985 for first time and is improved version of DSA both signature and public key of El Gamal are non -deterministic, its algorithm are as follow

Conclusion
In this article we claim which algorithm in cryptography is suitable for which propose so by reading this article user can find which algorithm is suitable for which propose .