Overview of Digital Signatures

Introduction To Networks and Communications (CS 555)

Presented byBharath Kongara

What is a Digital Signature?

An electronic signature that can be used to authenticate the identity of the sender of a message or the signer of a document.

Why Digital Signatures?

• To Provide Authenticity , Non-Repudiation and Integrity to electronic documents

• To use internet as the safe and secure medium for e-Commerce and e-Governance

Digital Signatures

• Each individual generates his own key pair ( Public key known to everyone and private key only to the owner)• Private key - Used for making digital owner• Public key – Used to verify the digital signature

How it works?

Step 1: Getting a Private and Public Key

Step 2: Signing an Electronic Document• Initiate the signing process • Create a digital signature• Append the signature to the document

How it works?Step 3: Validating a Digital Signature (Receiver Side)

• Initiate the validation process• Decrypt the digital signature• Compares the document fingerprint with the

calculated one

What is a Digital Certificate and who issues it?

• A digital certificate is an electronic document that uses a digital signature to bind together a public key with an identity.• The CA issues an encrypted digital certificate

containing the sender’s public key and a variety of other identification information.

Message Digest

Data to be encoded -> MessageHash value(Message)->Message Digest or Digest

Hash Functions• MD4• MD5 • SHA-1 • SHA-2 are generally used

Uses of Digital Signature and Overall Function

• Authentication • Integrity• Non-repudiation

References

• http://en.wikipedia.org/wiki/Cryptographic_hash_function• http://www.authorstream.com/Presentation/aSGuest41865-

360870-digital-signature-ccapresentation-1-science-technology-ppt-powerpoint/• http://www.arx.com/digital-signatures-faq/• http://en.wikipedia.org/wiki/Digital_signature• http://www.webopedia.com/TERM/D/digital_certificate.html

Thank You