Saturday, April 6, 2013

Cryptography




Cryptography

is the study of mathematical techniques related to aspects of information security, such as confidentially or privacy ,data integrity and entity authentication. Cryptography is not only means of providing information security, but rather one set of techniques. Confidentially means keeping information secret from all but those who authorized to see it. Data integrity means ensuring information has not been altered by unauthorized or unknown means. Entity authentication means corroboration of the identify of an entity.



Definition of cryptography


 Cryptography is the study of mathematical techniques related to aspects of information security, such as confidentially or privacy, data integrity and entity authentication. Cryptography is not the only means of providing information security, but rather one set of techniques.

Cryptography

Categories of cryptographic algorithm


There are main two types of cryptographic algorithm.
1: - Symmetric key
2: - Asymmetric key


Symmetric key

1.  Sender and Receiver share a key.          
2.  A secret piece of information used to encrypt or decrypt the message.
3.  If a key is secret, than nobody other than sender or receiver can read the
      message               
4.  If Alice and bank each has secret key, than they may send each other 
      private    message.
5.  The task of privately choosing a key before communication, however can 
      be problematic.
             

Asymmetric key

1.  Solves the key exchange problem by defining an algorithm which uses     
      two keys, each of which can be use to encrypt the message.
2.  If one is used to encrypt a message, another key must be used to 
      decrypt it.
3  This makes it possible to receive secure message by simply publishing one
      key (public key) and keeping another secret (private key).
4  Any one may encrypt a message using public key, but only the owner of
      the public key is able to read it.
5  In this way Alice may send private message to owner of a key-pair (the      
      bank) by encrypting it using their public-key. Only bank can decrypt it.
 


Goals of cryptography


The main goals of cryptography are
1: - Confidentially or privacy
2: - Data integrity
3: - Authentication
4: - Non-repudiation

 


Characteristics of a cryptographic algorithm


The main characteristics of cryptographic algorithm are
1: - Level of security
2: - Performance
3: - Ease of implementation
 

2 comments:

  1. In simple way you have nicely explained the meaning and purpose of cryptography. The figure clearly illustrates the process of this scheme. This is an ideal post for a fresher to learn about it easily.
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