SHA-256 Hash Generator

Generate SHA-256 (256-bit) hashes from text or files. The industry standard for security, used in Bitcoin, TLS, and code signing.

Enter text and click Generate to create a SHA-256 hash

Other Hash Algorithms

What is SHA-256?

SHA-256 (Secure Hash Algorithm 256-bit) is a cryptographic hash function from the SHA-2 family, producing a 256-bit (32-byte) hash value. Published by NIST in 2001, it is the most widely used secure hash function today, powering Bitcoin, TLS/SSL, digital signatures, and code signing.

How SHA-256 Works

SHA-256 processes data in 512-bit blocks through 64 rounds of compression. It maintains a 256-bit state (eight 32-bit words initialized to the first 32 bits of the fractional parts of the square roots of the first 8 primes). Each round applies sigma functions, majority/choice functions, and adds a round constant derived from cube roots of the first 64 primes.

Output

64 hex characters (256 bits)

Year

2001

Status

✓ Secure

Common Use Cases

  • Bitcoin and cryptocurrency mining
  • TLS/SSL certificate verification
  • Digital signatures (ECDSA with SHA-256)
  • Code signing and software verification
  • File integrity verification
  • Data deduplication and content addressing

Security Considerations

SHA-256 has no known practical attacks. The best theoretical attack reduces security from 256 bits to approximately 254.9 bits, which is negligible. SHA-256 is approved by NIST, NSA, and is the backbone of Bitcoin's security model. It is considered safe for all current applications.

SHA-256 vs Other Algorithms

SHA-256 offers the best balance of security and performance in the SHA-2 family. It's twice as fast as SHA-512 on 32-bit systems but slightly slower on 64-bit systems. Compared to SHA-3-256, SHA-256 is faster in software but SHA-3 offers a different internal structure as a hedge against SHA-2 vulnerabilities.

Frequently Asked Questions

What is SHA-256?
SHA-256 is a cryptographic hash function that produces a 256-bit hash. Part of the SHA-2 family designed by the NSA, it is the most widely used secure hash function, powering Bitcoin, TLS, and digital signatures.
Is SHA-256 secure?
Yes. SHA-256 has no known practical attacks. It provides 128 bits of collision resistance and 256 bits of preimage resistance, far beyond what is computationally feasible to break with current or foreseeable technology.
How does Bitcoin use SHA-256?
Bitcoin uses double SHA-256 (SHA-256 applied twice) for block hashing, transaction verification, and proof-of-work mining. Miners must find a nonce that produces a SHA-256 hash below a target value.
How long is a SHA-256 hash?
A SHA-256 hash is 256 bits (32 bytes), typically displayed as a 64-character hexadecimal string. Example: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
What is the difference between SHA-256 and SHA-512?
SHA-256 uses 32-bit operations and produces a 256-bit hash, while SHA-512 uses 64-bit operations and produces a 512-bit hash. SHA-512 is actually faster than SHA-256 on 64-bit processors but produces a longer output.
Can SHA-256 be used for password hashing?
No. While SHA-256 is cryptographically secure, it is too fast for password hashing. Attackers can compute billions of SHA-256 hashes per second. Use bcrypt, Argon2, or scrypt for passwords instead.
What is HMAC-SHA256?
HMAC-SHA256 combines SHA-256 with a secret key for message authentication. It's widely used in API authentication (AWS Signature V4), JWT tokens, and webhook verification.