Hashing · 256 bits, 64 hex characters
SHA-256
SHA-256 produces a 256-bit digest and is the default choice for integrity and signatures.
Key facts
| Output | 256 bits, 64 hex characters |
|---|---|
| Block size | 512 bits |
| Rounds | 64 |
| Standard | FIPS 180-4 |
| Security | No practical collision found |
| Common uses | TLS, signatures, content addressing |
The current default
SHA-256 is part of the SHA-2 family and the most common modern hash. Certificates, code signing, blockchain systems and content-addressed storage use it. No practical collision has been found, and the best generic collision attack still requires about 2^128 work.
It is fast, widely implemented and available in every browser through the Web Crypto API. That combination makes it the safe default when a protocol does not specify something else.
SHA-256 versus SHA-512
SHA-512 uses 64-bit words and a 1024-bit block, and can be faster than SHA-256 on 64-bit CPUs for large inputs. SHA-256 is more common in protocols and has a smaller digest. Both are secure; the choice usually follows the protocol or the platform.
Truncated variants such as SHA-224 and SHA-384 exist and are not the same as taking the first bytes of a longer digest. Use the named variant when a specification asks for it.
Frequently asked questions
Is SHA-256 enough for passwords?
No. It is too fast. Use a memory-hard or adaptive password hash.
Can I truncate SHA-256 to save space?
Truncation weakens collision resistance. Use the named truncated variant only when a standard defines it.