Network security cryptography ppt

Network security cryptography ppt

• 1.
  NETWORK SECURITY CRYPTOGRAPHY BY: R.Thushara Bharathi(CSE) S. Jahnavi (CSE)
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  WHAT IS NETWORK ∗A network Is an interconnection or a media between two or more systems to share information among them. ∗ The various threats caused to network are :  Remote Login  Application Backdoors  SMTP Session Hijackings  Operating System Bugs  Spams  Viruses etc.
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  NETWORK SECURITY ∗ Thesecurity provided to the network is called network security which at present is looming on horizon as a massive problem. ∗ There are two kinds of Network Security mainly as :  Transit Security : it just encrypts the packets to be transferred.  Traffic Security : it acts just as a screen between hosts & remote sites.
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  PROBLEMS & ATTACKS ∗There are few intertwined areas in network security as:  Secrecy  Authentication  Non-Repudiation  Integrity Control etc. ∗ The threats are classified into two categories : Passive Attacks : A passive attack is one in which the attacker eavesdrops and listens to the message but can’t modify the message. Active Attacks : An active attack is one in which the attacker modifies, deletes, replay or introduce new messages into the stream of message.
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  CRYPTOGRAPHY ∗ It isderived from the Greek word that meant for secret writing. ∗ Cryptography is the ability to send information between particulars in a way that it prevents others from reading the data. ∗ The data is transferred by applying two techniques by changing the plain text & Cipher texts as Encryption (P to C) & Decryption (C to P).
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  PRINCIPLES & SERVICESOF CRYPTOGRAPHY ∗ The two fundamental principles of cryptography are:  Messages must contain some Redundancy (information not needed to understand the message).  Some method is needed to foil replay attacks (validation of messages by timestamp) i.e. freshness. ∗ The services provided by the cryptography are as follows:     Integrity Checking Authentication Protection to the data Confidentiality of information etc.
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  ENCRYPTION & DECRYPTION ∗The way of converting the plain text to the cipher text by the means of few keys is called as “encryption”. ∗ The way of converting the cipher text to the plain text by the use of keys that are suitable to it is called as “decryption”.
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  SUBSTITUTION CIPHER ∗ Replacingof each letter or group of letters of plain text into cipher text by another letters is called as “substitution cipher”. ∗ The substitution may be :  Monoalphabetic Substitution  Digrams  Trigrams
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  TRANSPOSITION CIPHER ∗ Thechange offered in the position of the text i.e. By jumbling the words is called as “transposition cipher”. ∗ And the technique used here is termed as “mass technique”.
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  SECRET-KEY ALGORITHMS ∗ Theimplementation of a simple cryptography using single key is done by the secret-key algorithms. ∗ This can be done by p-box, s-box and product cipher.
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  ELEMENTS OF PRODUCTCIPHERS ∗ Transpositions & substitutions can be done through p-box (a). ∗ Substitutions can be done through s-box (b). ∗ Mapping of the p-box with s-boxes form product cipher (c).
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  PUBLIC-KEY ALGORITHMS ∗ Publickey algorithms are formed when it satisfies the following requirements:  D(E(P))=P.  Difficulty to deduce D from E.  E cannot be broken by a chosen plain text attack.
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  RSA ALGORITHM ∗ RSAis derived from the names of the 3 discoverers named Rivest, Shamir, Adleman. ∗ The RSA algorithm is one of the widely used in the key algorithms. ∗ But takes much time for the large volumes of data encryption. This is done by few mathematical principles as:  Choose 2 large primes.  Compute n=pxq & z=(p-1)x(q-1).  Find e, exd=1 mod z.
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  ADVANTAGES & DISADVANTAGES ∗Advantages :  Used to protect the data from the others.  Used to send the data / packet in a secured way from the source to destination.  Avoids in knowing the data in the way of sending. ∗ Disadvantages:  Hacking is done now-a-days easily even for the data encrypted with 48 bits though the bits are extended by 52-bits.
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  PROPOSED CONCEPT ∗ Asknown the data has been easily hacked even for the 52- bit encryption too. So, the encryption bits of 52-bits should be given with the combination of both numerals and alphabets ( for example one alphabet is placed for 13-bits each). ∗ The placement of alphabet is known only to the particular sender & receiver such that it secures the data to be sent.