2.  A 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 and was nor altered in
transit.
 Digital signatures are commonly used for software distribution,
financial transaction and in cases where it is important to detect
forgery and tampering.
 A digital signature authenticates electronic document in a similar
manner a handwritten signature authenticates a printed document.

3.  To provide authenticity,Integrity and Non-repudiation to electronic
documents.
 To use the Internet as the safe and secure medium for e-commerce
and e-governance.

4.  Owner public key.
 Owner name.
 Expiration date of public key.
 Name of the issuer(the CA that issue the digital ID)

Serial number of digital signature.

5. Cryptographic GoalsCryptographic Goals
Cryptographic goals
Data integrity Authentication Non-repudiation
Message
authentication
Entity authenticationArbitrary length
hash functions
Message
Authentication
codes (MACs)
Digital signatures
Authentication
primitives
Digital signatures
MACs
Digital
signatures
Symmetric-key
ciphers:
Block ciphers
Stream ciphers
Public-key
ciphers
Confidentiality

7. Paper Electronic
May be Forged Cannot be copied
Signature Independent of the
Document
Signature Depends on the
Document
Hand writting expert needed Any computer User
Error Prone Error Free
AuthenticityAuthenticity
IntegrityIntegrity
Non-Non-
repudiationrepudiation

8.  The Information Technology Act, 2000 provides for use of Digital
Signatures on the documents submitted in electronic form in order
to ensure the security and authenticity of the documents filed
electronically. Certification Agencies are appointed by the office of
the Controller of Certification Agencies (CCA) under the provisions
of IT Act, 2000. There are a total of seven Certification Agencies
authorised by the CCA to issue the Digital Signature Certificates.
 Tata Consultancy Services Ltd.
 National Informatics Centre.
 Institute for Development & Research in Banking Technology
(IDRBT)

9.  MTNL
 Customs & Central Excise
 Code Solutions Ltd., (A division of Gujarat Narmada Valley
Fertilisers Company Ltd.)
 Safescrypt
 e-Mudhra CA

10.  Using asymmetric – key cipher.
 Using keyed hash function.

11.  public-key cryptography involves the use of asymmetric key
algorithms.
 Asymmetric key algorithms used to create mathematically related
key pair.
 A secret private key and a published public key.
 Protects the confidentiality and integrity of a message.
 The message is encrypted using the public key,which can only be
decrypted using the private key.

13.  To preserve the integrity of a message,the
message is passed through an algorithm called
Hash Function.
 The hashed function creates a compressed
image of message that can be used as a
fingerprint.
 For Compatibility
 For Integrity
 For efficiency