signyourdoc
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Digital signatures are a secure electronic equivalent of handwritten signatures that authenticate the sender, ensure message integrity, and provide non-repudiation. They involve a process where a sender uses a private key to sign a document, which the receiver can verify using the sender's public key. Trusted Certification Authorities (CAs) play a crucial role in certifying public keys, establishing a trust model for secure communication.
signyourdoc
- 1. Digital Signature •Important application of public key Cryptography •Electronic form of Signature •Serves the same purpose as of handwritten signature but is much secure signyourdoc.com 9571333822
- 2. Why Digital Signature ? – Authenticate identity of sender – Ensure the original Content of Message – Non-RepudiationVerifiability by independent, public or third party signyourdoc.com 9571333822
- 4. How digital Signature works? User A User B Use A’s private key to sign the document Transmit via the Internet User B received the document with signature attachedVerify the signature by A’s public key stored at the directory
- 5. Digital Signature Generation and Verification Message Sender Message Receiver Message Message Hash function Digest Encryption Signature Hash function Digest Decryption Expected Digest Private Key Public Key
- 6. Certification Authority (CA) • A trusted agent who certifies public keys for general use (Corporation or Bank). – User has to decide which CAs can be trusted. • The model for key certification based on friends and friends of friends is called “Web of Trust”. – The public key is passing from friend to friend. – Works well in small or high connected worlds. – What if you receive a public key from someone you don’t know?
- 7. CA model (Trust model) Root Certificate CA Certificate Browser Cert. CA Certificate Server Cert.
- 8. Digital Certificates • Digital Certificate is a data with digital signature from one trusted Certification Authority (CA). • This data contains: – Who owns this certificate – Who signed this certificate – The expired date – User name & email address
- 10. Digital Signatures (1) Required Conditions: 1.Receiver can verify claimed identity of sender. 2.Sender cannot later repudiate(deny) contents of message. 3.Receiver cannot have concocted message himself.
- 11. Digital Signatures (2) • Asymmetric-key signatures • Symmetry-key signatures • Message digests signyourdoc.com 9571333822