INFORMATION SECURITY AND AUDIT
1. Overview of information security
2. Information and Network Security Policies
3. Cryptography and PKI
4. Network security applications
5. Design Principles
6. Compliance, Evaluation system and Law
7. Malicious logic and attacks
8. Vulnerability analysis and IT Audit
9. Intrusion detection and log analysis
LAB WORK -ISA
SOLVED PRACTICE QUESTIONS
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Digital Signature

A digital signature is a cryptographic technique used to validate the authenticity and integrity of digital messages, documents, or software. It serves as a digital equivalent of a handwritten signature or a stamped seal but with far more inherent security. Digital signatures are widely used in various security protocols and applications, including email communication, software distribution, and financial transactions.

  1. Key Pair:
    • Private Key: Used to create the digital signature. This key is kept secret by the signer.
    • Public Key: Used to verify the digital signature. This key is shared publicly.
  2. Hash Function:
    • A cryptographic algorithm that converts data into a fixed-size hash value (digest). Common hash functions include SHA-256 and SHA-3.
  3. Signature Algorithm:
    • An algorithm that uses the private key to create the digital signature from the hash of the message. Examples include RSA, DSA, and ECDSA.

Process of Creating a Digital Signature:

  1. Hashing:
    • The original message or document is processed through a hash function to produce a hash value (message digest). This hash value uniquely represents the original data.
  2. Signing:
    • The hash value is encrypted using the signer's private key, creating the digital signature. This ensures that only the holder of the private key could have created the signature.

Process of Verifying a Digital Signature:

  1. Hashing:
    • The recipient processes the received message or document through the same hash function used during the signing process to produce a hash value.
  2. Decrypting:
    • The recipient decrypts the digital signature using the signer's public key, which retrieves the original hash value created during the signing process.
  3. Comparing:
    • The recipient compares the decrypted hash value with the hash value computed from the received message. If they match, the message is verified as authentic and unaltered.

Applications of Digital Signatures:

  1. Email Security:
    • Digitally signed emails ensure that the sender's identity is authenticated and the message has not been tampered with.
  2. Software Distribution:
    • Software developers use digital signatures to sign software packages, ensuring users that the software is authentic and has not been modified.
  3. Document Signing:
    • Legal and business documents are often signed digitally to provide proof of the signer's identity and the document's integrity.
  4. Financial Transactions:
    • Digital signatures secure online transactions, ensuring the authenticity and integrity of transaction data.
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