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SHA-256

SHA-256 is the 256-bit-output member of the SHA-2 family, widely used in TLS, blockchains, and cryptographic applications, with no known practical attacks.

Purpose

Provides a 256-bit secure hash meeting modern collision and preimage security requirements.

Mechanism

Processes input in 512-bit blocks, maintaining a 256-bit state (eight 32-bit words). Each block goes through 64 steps of nonlinear transforms (with message schedule and round constants) updating the state. Outputs a 256-bit digest.

Use cases

  • TLS 1.2/1.3 certificate signatures
  • Bitcoin proof of work
  • File integrity verification
  • HMAC-SHA256 message authentication

Examples

  • Input 
    hello
    Output 
    2cf24dba5fb0d30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824

    256 bits = 64 hex characters

Common errors

Hashing passwords directly with SHA-256 (no salt)
Use PBKDF2/bcrypt/Argon2

Related terms

SHA-1
SHA-1 is a 160-bit cryptographic hash function designed by the NSA; Google published the SHAttered collision in 2017, and it has been deprecated across standards.
GLOSSARY
SHA-512
SHA-512 is the 512-bit-output member of the SHA-2 family; faster than SHA-256 on 64-bit platforms, providing a higher security margin.
GLOSSARY
SHA-3 (Keccak)
SHA-3 is the hash standard based on the Keccak sponge construction; structurally entirely different from SHA-2, it serves as a fallback in case SHA-2 is broken.
GLOSSARY
BLAKE2
BLAKE2 is a hash function designed by Jean-Philippe Aumasson et al.; faster than MD5 with security comparable to SHA-3, a high-performance alternative to SHA-2/3.
GLOSSARY
HMAC
HMAC (Hash-based Message Authentication Code) is a message authentication code combining a hash function with a secret key, providing integrity and authenticity.
GLOSSARY

Related tools

Hash Calculator
Compute MD5, SHA-1, SHA-256, or SHA-512 hashes with hex or Base64 output. Free, private, and 100% client-side.
TOOL
Hash Compare
Compare MD5, SHA-1, SHA-256, SHA-384, SHA-512 of the same input. Free, private, 100% client-side.
TOOL
HMAC Generator
Generate HMAC (Keyed-Hash Message Authentication Code) with SHA-1/256/512. Free, private, and 100% client-side.
TOOL

References