Hash Functions: SHA-256 and Beyond
Explore cryptographic hash properties: collision resistance, preimage resistance, and applications.
What is a Cryptographic Hash Function?
A cryptographic hash function takes arbitrary-length input and produces a fixed-length output (digest). It must be: deterministic, fast to compute, preimage-resistant (can't reverse), collision-resistant (can't find two inputs with same hash), and avalanche-sensitive (small change → completely different hash).
SHA-2 Family
The SHA-2 family (designed by NSA, standardized by NIST) includes:
- SHA-256 — 256-bit output, widely used
- SHA-384 — 384-bit output
- SHA-512 — 512-bit output, faster on 64-bit CPUs
SHA-256 is used in Bitcoin, TLS certificates, and Git commit IDs.
All lessons in this course
- Symmetric Encryption: AES and Stream Ciphers
- Asymmetric Encryption: RSA and Elliptic Curves
- Hash Functions: SHA-256 and Beyond
- Digital Signatures and Certificates