Ruhi Ppt -Digital Signature

8/6/2019 Ruhi Ppt -Digital Signature

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DIGITAL SIGNATUREDIGITAL SIGNATURE

Ruhi Jain

Information Technology

07EAYIT045


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Digital SignatureDigital Signature

I agree

Ecdjbh75dh877vnjid46vbc98866gf

My place of birth is Mumbai

Jhjk9869bhjnklkm565cbjbkjkjd869

I am an engineer

Lokinx789dxjh334bmjhk898cbhgfh

I am 30 years old

Jyuir48jhd898jhgjjkl58jh545hb009b

o These are digital signature of same person on different

documents


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ConceptConcepty A 1024 bit number is used which is a very big

number

y Large pair of numbers exist in this range with

each pair having property

A message encrypted with only one element ofthe pair can be decrypted only by other

element of the pair

y Two number of a pairs are called keys , the

Public Key and the Private Key. User himself

generates his own pair of keys


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y Any message irrespective of length can be

compressed into smaller length message

called Digest or Hash

y Small change in message will change the

hash value.


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Digital SignatureDigital Signature


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What is Digital Signature ?What is Digital Signature ?

y A digital signature is a mathematical

scheme for demonstrating the

authenticity of a digital message or

document.

y Digital signature are numbers.

y They are document content dependent.

y Digital signatures employ a type ofasymmetric cryptography.


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Each individual generates his own pair of

keys.

y Public Key known to everyone and is

used for making digital signature.

y Private Keys known only to owner and

is used to verify digital signature.


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DefinitionDefinition

A digital signature scheme typically consists of threealgorithms:

y A key generation algorithm that selects a privatekey uniformly at random from a set of possible

private keys. The algorithm outputs the private keyand a corresponding public key.

y A signing algorithm that, given a message and aprivate key, produces a signature.

y A signature verifying algorithm that, given a

message, public key and a signature, either acceptsor rejects the message's claim to authenticity.


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Digital Signature DiagramDigital Signature Diagram


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Public Key Infrastructure(PKI)Public Key Infrastructure(PKI)

y Some trusted agency is required which

certifies the association of an individual

with the key.

Certifying authority(CA)

y This association is done by issuing a

certificate to user by CA.

Public Key Certificate(PKC)

y All public key certificates are digitally

signed by CA.


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Drawbacks of paper signatureDrawbacks of paper signature

y They may be forged.

y They are document independent.

y Handwriting experts needed.

y Error prone.


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Why use Digital Signature???Why use Digital Signature???

y Authenticity

y Integrity

y Non-repudiation


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ApplicationApplication

Judiciary

y Instant posting of judgments on web

y Secured electronic communication

y Authentic archiving of records

y Submissin of affidavits

y

Giving certified copies of judgment


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Telecommunication

y Subscribers

Service management

mobile authentication of messages

mobile phone as credit cards

y Internal

Inter/intra office s authentic

communicationProcurement of material

Network management functions


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E-Governance

y Empowering citizens

accountability

transparency

elimination of intermediatory

encouraging citizen to exercise their

rights


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QUERIESQUERIES

Ruhi Ppt -Digital Signature

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