Cryptography(97 2003)

8/4/2019 Cryptography(97 2003)

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CRYPTOGRAPHYHiding the Word


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What the CRYPTOGRAPHY is?

Cryptographyis the scienceof providingsecurity forinformation.

The art of protecting information by transforming it

into an unreadable format, called cipher text. Onlythose who possess a secret keycan decipher themessage into plain text. Cipher Textcansometimes be broken by cryptanalysis, alsocalled codebreaking, although moderncryptography techniques are virtuallyunbreakable.
http://www.webopedia.com/TERM/C/cipher_text.htmhttp://www.webopedia.com/TERM/C/plain_text.htmhttp://www.webopedia.com/TERM/C/plain_text.htmhttp://www.webopedia.com/TERM/C/cipher_text.htm


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Everyone has secrets; some have more thanothers. When it becomes necessary to transmitthose secrets from one point to another, it'simportant to protect the information while it's intransit. Cryptography presents various methods fortaking legible, readable data, and transforming itinto unreadable data for the purpose of secure

transmission, and then using a key to transform itback into readable data when it reaches itsdestination.


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Its Foundation or From where it came?

It is derived from Greek wordkryptos and logos whichmeans hidden and word.

As all want a concealed &covert communication of

their task.

As the Internet and other forms ofelectronic communication become moreprevalent, electronic security isbecoming increasingly important.Cryptography is used to protect e-mailmessages, credit card information, andcorporate data. One of the most popularcryptography systems used on theInternet is Pretty Good Privacybecause

it's effective and free.
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Encryption & DecryptionData that can be read and understood without any special measuresis calledplaintextor cleartext.

The method of disguising plaintext in such a way as to hideits substance is called encryption

Encrypting plaintext results in unreadable gibberish calledciphertext

The process of reverting ciphertext to its originalplaintext is called decryption.


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Categorization:

Public key

Private key..

Keys:A key is a value that works with a cryptographic

algorithm to produce a specific ciphertext. Keys arebasically really, really, really big numbers. Key size ismeasured in bits; the number representing a 1024-bitkey is darn huge. In public key cryptography, the biggerthe key, the more secure the ciphertext.

On this basis Cryptography is classified as :-


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Private key!!orConventional key!!


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Private key!!

orConventional key!!

Conventional cryptography, also called secret-keyor symmetric-keyencryption, one key is used both for encryption and decryption. TheData Encryption Standard (DES) is an example of a conventionalcryptosystem that is widely employed by the Federal Government


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Publickey!!

Anyone can see!!


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Public key!!

The problems of key distribution are solved by public key cryptography,theconcept of which was introduced by Whitfield Diffie and Martin Hellman in1975.

Public key cryptography is an asymmetric scheme that uses a pairof keysfor encryption: a publickey, which encrypts data, and a correspondingprivate, or secretkey for decryption.

As, You publish your public key to the world while keeping your private keysecret. Anyone with a copy of your public key can then encrypt informationthat only you can read. Even people you have never met.


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conventional cryptography was oncethe only available means for relayingsecret information, the expense ofsecure channels and key distribution

relegated its use only to those whocould afford it, such as governmentsand large banks (or small children withsecret decoder rings). Public keyencryption is the technologicalrevolution that provides strong

cryptography to the adult masses.

Public key cryptography is that it allowspeople who have no preexisting security

arrangement to exchange messages securely.The need for communications involve onlypublic keys, and no private key is evertransmitted or shared. Some examples ofpublic-key cryptosystems are RSA ,Diffie-Hellman and DSA, the Digital Signature

Algorithm


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Digital signatures

A major benefit of public key cryptography is that it provides a method for employingdigital signatures. Digital signatures enable the recipient of information to verify theauthenticity of the informations origin, and also verify that the information is intact.


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Secured Digital Signature:The system described above has some problems. It is slow, and it produces an

enormous volume of data - at least double the size of the original information. Animprovement on the above scheme is the addition of a one-way hash function in theprocess. A one-way hash function takes variable-length input - in this case, amessage of any length, even thousands or millions of bits - and produces a fixed-length output; say, 160-bits. The hash function ensures that, if the information ischanged in any way - even by just one bit - an entirely different output value isproduced.


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AdvantageHigh level security..

High Integrity

No unauthorized use.No trespassing..

.


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Exploit

Banking purpose..Credit Card

A.T.MGovernment agenciesMilitary forces


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Provides data security.

Reduces the risk of intruders.

Avoid risk of getting disrupted data.

CONCLUSION


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ANY QUERIES??


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THANK YOU !!!!

HAVE A NICETIME!!!!!!

Documents

Cryptography(97 2003)