Objective: Understand the role, mechanism, and applications of digital signatures in cryptography.

Introduction to Digital Signatures

Key Concepts

  1. Mechanism of Digital Signatures:
    • Involves creating a hash of the original data and then encrypting this hash with the signer’s private key.
    • Verification is done by decrypting the signature with the signer’s public key and comparing the decrypted hash with a freshly computed hash of the original data.
  2. Public Key Infrastructure (PKI):
    • A framework of policies, hardware, software, and procedures needed to create, manage, distribute, use, store, and revoke digital certificates.
    • Essential for the management of public keys used in digital signatures.

Common Digital Signature Standards

  1. RSA-Based Signatures:
    • Utilizes the RSA algorithm for signing and verification processes.
    • Commonly used due to its security and widespread support.
  2. ECDSA (Elliptic Curve Digital Signature Algorithm):
    • A variant of the Digital Signature Algorithm (DSA) that uses elliptic curve cryptography.
    • Offers better security with shorter key lengths compared to RSA.

Hands-on Exercise: Creating and Verifying a Digital Signature


  1. Select or create a digital document to sign.
  2. Generate a hash of the document.
  3. Encrypt the hash with your private key to create a digital signature.
  4. To verify, decrypt the digital signature with the corresponding public key.
  5. Compare the decrypted hash with a new hash of the document to ensure they match.

Practical Application

Further Reading and Resources