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SHA-256 Generator

Generate SHA-256 hash instantly using this free and secure online tool.

SHA-256 Generator

SHA-256 Checker

What is SHA-256?

SHA-256 is part of the SHA-2 family of cryptographic hash functions and is widely used for data integrity and security applications. It produces a fixed-size 256-bit (32-byte) hash, typically represented as a 64-character hexadecimal string.

History of SHA-256

SHA-256 was designed by the National Security Agency (NSA) and published by the National Institute of Standards and Technology (NIST) in 2001 as part of the SHA-2 standard. It was created to address vulnerabilities in its predecessor, SHA-1, which had begun to show weaknesses against collision attacks.

How SHA-256 Works

SHA-256 takes an input message and processes it in several steps to produce a hash:

  • Message padding: the input is padded to a multiple of 512 bits.
  • Message parsing: the padded message is divided into 512-bit blocks.
  • Initialization: eight 32-bit words are initialized with predefined constants.
  • Compression function: each block is processed through a series of logical operations, modular additions, and bitwise shifts.
  • Final hash: after all blocks are processed, the eight words are concatenated to produce the final 256-bit hash.

SHA-256 Calculation Example

For example, hashing the string hello using SHA-256 results in:

2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824

Where SHA-256 is Used

  • Digital signatures and certificates
  • TLS/SSL for secure web communication
  • Blockchain technologies (Bitcoin, Ethereum, etc.)
  • File integrity checks (e.g., verifying downloads)
  • Commit hashes in Git version control

Important Note About Passwords

SHA-256 should not be used to store passwords. Although it is cryptographically secure, it is designed to be fast, making it vulnerable to brute-force and dictionary attacks. For passwords, use specialized algorithms like bcrypt,scrypt, or Argon2which are intentionally slow and include salt to protect against these attacks.

Sources & References

  • NIST FIPS PUB 180-4: SHA-2 Standard
  • Wikipedia: SHA-2
  • Bruce Schneier, Applied Cryptography, 2nd Edition, 1996, Wiley
  • William Stallings, Cryptography and Network Security: Principles and Practice, 8th Edition, 2019, Pearson

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