Santosh Seminar

8/6/2019 Santosh Seminar

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INTRODUCTIONA digital signature scheme typically consists of three

algorithms:

Key generation algorithm

Signing algorithm

Signature verifying algorithm

Two main properties are required:-

1)a signature generated from a fixed message and fixed

private key should verify the authenticity of that

message by using the corresponding public key.2) It should be computationally infeasible to generate a

valid signature for a party who does not possess the

private key.


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HISTORY

In 1976, Whitfield Diffie and Martin Hellman first

described the notion of a digital signature scheme.

The first widely marketed software package to offer

digital signature was Lotus Notes 1.0, released in 1989,

which used the RSA algorithm.


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WHAT IS A DIGITALSIGNATURE

BAPUNI

( BAPUNIS PUBLIC KEY)

( BAPUNIS PRIVATE KEY )

BAPUNI has been given two keys. One ofBAPUNI's keys is called a Public Key, the other iscalled a Private Key.


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Bapuni s Co-worker

:-

Anyone can get Bapuni 's

Public Key,

but Bapuni keeps his

Private Key to himselfBapuni 's Public key is available to anyone whoneeds it, but he keeps his Private Key to himself.Keys are used to encrypt information.

Encrypting information means "scrambling itup", so that only a person with the appropriate keycan make it readable again.Either one of Bapuni's two keys can encrypt data,

and the other key can decrypt that data.


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"Hey bapuni,how about HNFmsEm6Un

BejhhyCGKOK

lunch at Taco Bell. JUxhiygSBCEiC 0QYIh/

hear they have free refills!" Hn3xgiK Bcy LK1

UcYiY lxx2lCFHDC/A

HNFmsEm6Un BejhhyCGKOK "Hey bapuni, how about

JUxhiygSBCEiC 0QYIh/ Hn3xgiK lunch at Taco Bell.

BcyLK1UcYiY lxx2lCFHDC/A I hear they have freerefills!"

With his private key and the right software,bapuni can put digital signatures on documentsand other data.A digital signature is a "stamp" bapuni places onthe data which is unique to bapuni, and is verydifficult to forge.


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To sign a document,bapunis software willcrunch down the data into just a few lines by aprocess called "hashing". These few lines arecalled a message digest. (It is not possible to

change a message digest back into the originaldata from which it was created.)


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bapuni's software then encrypts the messagedigest with his private key. The result is thedigital signature.

Finally, bapunis software appends the digitalsignature to document. All of the data that washashed has been signed.


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USES OF DIGITALSIGNATURES

As organizations move away from paperdocuments with ink signatures or authenticity

stamps, digital signatures can provide addedassurances of the evidence to provenance,identity, and status of an electronic document as well as acknowledging informed consent andapproval by a signatory.

The United States Government Printing Office(GPO) publishes electronic versions of thebudget, public and private laws, andcongressional bills with digital signatures.Universities including Penn State, University ofChicago, and Stanford are publishing electronicstudent transcripts with digital signatures.


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DIGITALSIGNATURES VS. INK ON PAPER

SIGNATURES An ink signature can be easily replicated from onedocument to another by copying the image manually ordigitally.Digital signatures cryptographically bind an electronicidentity to an electronic document and the digital signaturecannot be copied to another document.Paper contracts often have the ink signature block on thelast page, and the previous pages may be replaced after a

signature is applied.Digital signatures can be applied to an entire document,such that the digital signature on the last page will indicatetampering if any data on any of the pages have been altered.


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CONCLUSION

It is the best technology for the Security point of view.

We can easily handle this technology, for overcome

many problems.


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BIBLOGRAPHY

J. Katz and Y. Lindell, "Introduction to ModernCryptography" (Chapman & Hall/CRC Press, 2007)For books in English on electronic signatures, see:Stephen Mason, Electronic Signatures in Law (Tottel,second edition, 2007);Dennis Campbell, editor, E-Commerce and the Lawof Digital Signatures (Oceana Publications, 2005);Lorna Brazell, Electronic Signatures Law andRegulation, (Sweet & Maxwell, 2004);M. H. M Schellenkens, Electronic SignaturesAuthentication Technology from a Legal Perspective,(TMC Asser Press, 2004).

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