Digital Signature

THE INSTITUTE OF CHARTERED ACCOUNTANTS OF INDIA

RAHUL YADAV

BATCH COMMENCEMENT DATE: 2ND DECEMBER 2013 PROJECT TOPIC: EXPAIN DIGITAL SIGNATURE WITH EXAMPLES.

SUBMITTED BY: -

CRO0428146

ITT CENTRE NAME: BIKANER BRANCH OF CIRC OF ICAI

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BIKANER BRANCH OF CIRC OF ICAI C-I009

BATCH NO.: Bikaner-12/13/81 CA. RAJIV AERON MISS SONALI JAIN BRANCH CHAIRMAN FACULTY MEMBER


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This Is To Certify That MR. RAHUL YADAV Has Under Taken A Project On DIGITAL SIGNATURE WITH EXAMPLES . After Going Through The Report, We Wish To Record Our Satisfaction & Commend To MISS SONALI JAIN For The Effort Put In By Their In This Exercise.

CERTIFICATE

CA. RAJIV AERON MISS SONALI JAIN BRANCH CHAIRMAN FACULTY MEMBER

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SUBMITTED BY RAHUL YADAV UNDER THE GUIDANCE OF MISS SONALI JAIN (I.T.T. FACULTY)

Submitted In Partial Fulfillment For The I.T. Training Conducted By Bikaner Branch Of I.C.A.I For The Course Of I.P.C.C.BATCH NO. BIKANER-12/13/81

REG. NO. BKN/13-14/1607

DIGITAL SIGNATURE WITH EXAMPLES


Acknowledgement

While coming on acknowledgement, it seems to me closing of long chapter of reminiscences which bloomed and gloomed at BRANCH CHAIRMEN CA Rajiv Aeron, BIKANER BRANCH OF CIRC OF ICAI, BIKANER.

This is my proud privilege to express my sincere and deep sense of gratitude my faculty member Ms. Sonali Jain for inspiration guidance, persistent involvement, scholarly suggestion and constructive critical supervision throughout the pursuit of present study.

And finally many thanks to all those friends who kept company and who directly or indirectly helped me in the completing of this project work.

RAHUL YADAV5Submitted By :- Rahul Yadav

ITT Reg. no. :- BKN/2013-14/1607

6Submitted By :- Rahul Yadav ITT Reg. no. :- BKN/2013-14/1607

Digital Signature

Introduction ….8-11 How they work ..13-15 What is D.S Technology .…16 Application ……17 Why use..Reason …18-23 WYSIWUS …..24 Public key Certificate …..25 Digital Certificate .….26 Why Digital Signature …..27 Paper vs Digital Signature ….28 Conclusion ….29 Bibliography …..30

INDEX

Submitted By :- Rahul Yadav ITT Reg. no. :- BKN/2013-14/1607 7

INTRODUCTIONA DIGITAL SIGNATURE is a mathematical scheme for demonstrating the authenticity of a digital message or document. A valid digital signature gives a recipient reason to believe that the message was created by a known sender, such that the sender cannot deny having sent the message(authentication and non-repudiation)and that the message was not altered in transit(integrity). Digital signatures are commonly used for software distribution, financial transactions, and in other cases where it is important to detectforgery or tampering.



Digital signatures are often used to implement electronic signatures, a broader term that refers to any electronic data that carries the intent of a signature, but not all electronic signatures use digital signatures. In some countries, including the United States, India, and members of the European Union, electronic signatures have legal significance. For messages sent through a non secure channel, a properly implemented digital signature gives the receiver reason to believe the message was sent by the claimed sender. Digital signatures are more difficult to forge than the handwritten type. Digital signatures can also provide non-repudiation, meaning that the signer cannot successfully claim they did not sign a message.

EXPLANATION


A digital signature scheme typically consists of three algorithms:-

A key generation algorithm that selects a private key uniformly at random from a set of possible private keys. The algorithm outputs the private key and a corresponding public key.

A signing algorithm that, given a message and a private key,

produces a signature.

A signature verifying algorithm that, given a message, public key and a signature, either accepts or rejects the message's claim to authenticity.


In 1976, Whitfield Diffie and Martin Hellman first described the notion of a digital signature scheme, although they only conjectured that such schemes existed.

Soon afterwards, Ronald Rivest, Adi Shamir, and Len Adleman invented the RSA algorithm, which could be used to produce primitive digital signatures. .

The first widely marketed software package to offer digital signature was Lotus Notes 1.0, released in1989, which used the RSA algorithm..

HISTORY


BOB ALICE

PLAIN TEXTDear Alice– The MeetingWill be Held in Embassy .

Public key(e,n)Private key(d)

CIPHERTEXTQrne cliae– Gur zasder bh ke measy

Encr

yptio

n fu

nctio

n

ORIGINAL PLAIN TEXTDear Alice—The Meeting Will be Held in Embassy

Dec

rypti

on

func

tion

No Secret key is ever exchanged.

Alice does not need her own key to use the system.


BOBALICE

I Hereby Give You A Raise.

I Hereby Give You A Raise192 2343 9102

I Hereby Give You A Raise.I Hereby Give You A Raise.

Public (e,n)Private (d)

Encrypt with the Private Key Attach to the end of the original message.

Decrypt with the Public Key Authenticate by Comparing to Plaintext Message


BOB

I Hereby Give You A Raise.

I Hereby Give You A Raise192 2343

9102

I Hereby Give You A Raise.Haye ahge kae gakg.

ALICEEvil

Evil Faked

Public (e,n)

Signature does not Match Message=>

Message not Authenticated


What is Digital Signature Technology…??Generating message’s digest (hash result)

Using Public Key to encrypt hash result

Result of the encryption: digital signature

Sender sendsmessage,digital signature andcertificate to receiver

Receiver wants to checkIntegrity :-Generating hash result, compare it to the sender’s hash result and decrypting the message with the sender’s public keyAuthenticity :-Can be checked by means of the certificate


Some common reasons for ApplyingDigital Communication

Although messages may often include information about the entity sending a message, that information may not be accurate. Digital signatures can be used to authenticate the source of messages.

The importance of high confidence in sender authenticity is especially obvious in a financial context.

For example, suppose a bank's branch office sends instructions to the central office requesting a change in the balance of an account. If the central office is not convinced that such a message is truly sent from an authorized source, acting on such a request could be a grave mistake.

Authentication :-


How do we do this if theDocument is Digital and Not Paper..?


Has this Email Signed..?Graphic

file

This can be Forged easliy…!


A True Signature: Is Authentic. Cannot be Forged. Cannot be Refused. Proves document has not been Altered. Cannot be Repudiated.

Digital Signature Which Do this for Electronic Document.


In many scenarios, the sender and receiver of a message may have a need for confidence that the message has not been altered during transmission. Although encryption hides the contents of a message, it may be possible to change an encrypted message without understanding it.

However, if a message is digitally signed, any change in the message after signature invalidates the signature. Furthermore, there is no efficient way to modify a message and its signature to produce a new message with a valid signature.


Non-repudiation, or more specifically non-repudiation of origin, is an important aspect of digital signatures. By this property, an entity that has signed some information Documents cannot at a later time deny having signed it.

. Checking revocation status requires an "online" check, e.g. checking Very roughly this is analogous to a vendor who receives credit-cards first checking online with the credit-card issuer to find if a given card has been reported lost or stolen.

Non-repudiation :-


In order to be semantically interpreted, the bit string must be transformed into a form that is meaningful for humans and applications, and this is done through a combination of hardware and software based processes on a computer system.

WYSIWYS means that the semantic interpretation of a signed message cannot be changed. In particular this also means that a message cannot contain hidden information that the signer is unaware of, and that can be revealed after the signature has been applied.

WYSIWYS is a necessary requirement for the validity of digital signatures, but this requirement is difficult to guarantee because of the increasing complexity of modern computer systems.


A public key certificate (also known as a digital certificate) is an electronic document that uses a digital signature to bind a public key with an identity — information such as the name of a person or an organization, their address, and so forth.

Public Key Certificate

In a typical public key infrastructure (PKI) scheme, the signature will be of a certificate authority (CA). There are Three Companies in INDIA which certified the Digital Signature:- 1). Infosys 2). Wipro 3). TCS

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A Digital Certificate typically contains the:

Owner's public key

Owner's name

Expiration date of the public key

Name of the issuer (the CA that issued the

Digital Certificate)

Serial number of the Digital Certificate

Digital signature of the issuer Submitted By :- Rahul Yadav

ITT Reg. no. :- BKN/2013-14/1607

A Digital Certificate is issued by a Certification

Authority (CA) and signed with the CA's

private key.


Why Digital Signature..? Authentication,

Integrity,

Low cost,

Eliminates the use of paper,

Faster Procedures,

Completely Secure.


Paper SignatureVS.

Digital SignaturePARAMETER PAPER DIGITAL

Authenticity May be Forged. Can not be Forged.

Integrity Signature independent of the Document.

Signature depends on the contents of the documents.

Non- Repudiation a. Handwriting expert needed.b. Error prone.

a. Any computer user.b. Error free.


ConclusionDigital signatures are a valuable technology

for every major corporation. Combined with RSAand PKI for certificate lifecycle management digital signatures can speed up business processes.

It as well supports any other security application based on digital certificates. For instance, Virtual Private Networks, e-mail encryption, and secure WWW portals can be realized with the digital certificates provided by RSA and PKI. The more applications a PKI is used for, the more economic it gets.


BIBLIOGRAPHY

I T T MODULES

MISS SONALI JAIN

My Hard Work

My Efforts

My Creativity

Digital Signature

Education

Transcript of Digital Signature