Question 1

What is a cryptographic hash function?

Accepted Answer

A cryptographic hash function takes any input and produces a fixed-length digest. The same input always produces the same output, but even a single character change produces a completely different hash — this sensitivity is called the avalanche effect.

Question 2

Which hash algorithm should I use?

Accepted Answer

For file integrity verification: SHA-256 or SHA-512. For passwords: never store raw hashes — use bcrypt, scrypt, or Argon2 with a unique salt. Avoid MD5 and SHA-1 for security purposes as both are cryptographically broken.

Question 3

What is the difference between MD5, SHA-1, and SHA-256?

Accepted Answer

MD5 produces a 128-bit (32-char) hash; SHA-1 produces 160-bit (40-char); SHA-256 produces 256-bit (64-char). MD5 and SHA-1 have known collision vulnerabilities. SHA-256 is the current recommended standard for most security applications.

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