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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