Objective: Understand the purpose, functionality, and applications of cryptographic hash functions.

Introduction to Hash Functions

Key Concepts

  1. Understanding Hash Values:
    • The output of a hash function, known as the hash value or hash, appears as a seemingly random string of characters.
    • Even a small change in the input will significantly change the hash.
  2. Applications of Hash Functions:
    • Data Integrity Checks: Verifying the integrity of data or files.
    • Password Storage: Storing passwords in hashed form for security.
    • Digital Fingerprints: Unique representation of data for identification.

Common Hash Algorithms

  1. SHA (Secure Hash Algorithm) Family:
    • Includes SHA-1, SHA-256, and SHA-512 among others.
    • Widely used in various security applications and protocols.
  2. MD5 (Message Digest Algorithm 5):
    • Once widely used but now considered vulnerable and not recommended for security-critical applications.

Hands-on Exercise: Generating and Comparing Hash Values


  1. Choose a piece of text or a file.
  2. Generate the hash value using an algorithm like SHA-256.
  3. Modify the input slightly (e.g., change a character in the text).
  4. Generate the new hash and compare it with the original hash to observe the differences.

Practical Application

Further Reading and Resources