Introduction to DIGITAL SIGNATURE in Cryptography.pptx

Introduction to DIGITAL SIGNATURE

1. INTRODUCTION TO DIGITAL SIGNATURE PRESENTED BY: Mehak Parvaiz 182143

2. Why We Need Digital Signature. A real life example could be the case of a user C, posing as a user A, sending a funds transfer request(from A’s account to C’s account) to bank B. The bank might happily transfer the funds from A’s account to C’s account, after all, it would think that user A has requested for the funds transfer. A I am user A B C

3. User A could send a funds transfer request to bank B over the internet. After the bank performs the funds transfer as per A’s instructions, A could claim that he never sent the fund transfer instructions to the bank. Thus, A denies, his funds transfer instructions. That is the reason, we need digital signature. A B I never send that message, which you claim to have recieved

4. Digital Signature A digital signature is a mathematical technique used for message authentication, non-repudation and message intregity. Digital signature are based on public key cryptography, also known as asymmetric crypography. Using a public key algorithm, two keys are generated-- one public and one private. For encryption and decryption, the person who creates the digital signature uses a private key to encrypt signature-related data. The only way to decrypt that data is with the signer’s public key. If the recipient can’t open the document with the signer’s public key, that indicates there’s a problem with the document or the signature. This is how digital signatures are authenticated. {Note: It is not used for confidentiality.}

5. How It Work Sender Reciever

6. Confidentiality A digital signature does not provide confidential communication. If confidentiality is required, the message and the signature must be encrypted using either a secret-key or public-key cryptosystem. Original Message Hash algorithm Hash code Encryption Private key A Digitally Signed Document Encryption Public key B Encrypted Message Decrypted Message Original Message Hash Algo Decryption Hash Code Hash Code Digital Signature Decryption Private key B Public key A Signature are valid when hash code are equal

7. Application of digital signature Order through internet. Online Contract / agreement. Online payment. Transfer Of Authenticate information. Transfer of government. documents etc.

8. Thank You