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SHA-512 Hash Generator

SHA-512 with a real, byte-verified SHA-512crypt ($6$) implementation for Linux /etc/shadow-style password hashes, a live SHA-256 vs SHA-512 speed benchmark, and the SHA-2 family in one comparison table.

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What this tool does

Computes SHA-512 from text or a file, a real SHA-512crypt ($6$) implementation -- the exact algorithm Linux uses to hash passwords in /etc/shadow -- a live speed benchmark comparing SHA-256 against SHA-384 and SHA-512 in your own browser, and a self-check against the official standard test vectors. This is a focused, SHA-512-specific companion to this site's general Hash Generator -- here for the one genuinely counter-intuitive fact about SHA-512 and the one real system that still builds passwords directly from it.

SHA-512 is often faster than SHA-256 -- despite the bigger output

This surprises most people: on a 64-bit CPU, SHA-512 can out-throughput SHA-256 even though it produces twice the digest size. The reason is architectural, not cryptographic -- SHA-256 operates on 32-bit words, while SHA-512 operates on 64-bit words, which is exactly the native register width of basically every CPU made since the mid-2000s. SHA-256 leaves half of each 64-bit operation unused; SHA-512 doesn't. The benchmark on this page runs both algorithms against identical data in your actual browser so you can see the real throughput difference on your own hardware, rather than taking it on faith.

SHA-512crypt: the algorithm behind /etc/shadow's $6$ hashes

Unix password hashes stored with a $6$ prefix use SHA-512crypt, specified by Ulrich Drepper in 2007/2012 -- a proper key-derivation construction built on top of raw SHA-512, not raw SHA-512 itself. It salts the password, runs a deliberately convoluted mixing step, and then iterates the whole thing 5,000 times by default (tunable up to 999,999,999 rounds via a rounds=N$ prefix) -- exactly the kind of deliberate slowness that makes a hash suitable for passwords, unlike bare SHA-256 or SHA-512 used directly. It predates Argon2id and bcrypt's wider adoption and is still what /etc/shadow uses on most Linux systems that haven't switched to yescrypt. The implementation here follows Drepper's specification exactly and is verified byte-for-byte against openssl passwd -6 output.

Self-check against FIPS 180-4 and RFC 4231

FIPS 180-4 publishes the official SHA-512 test vectors and RFC 4231 publishes the official HMAC-SHA512 test vectors -- computed live here via the browser's native Web Crypto implementation and checked against the published values.

The SHA-2 family

SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224 and SHA-512/256 are all the same underlying design at different word sizes and truncations -- SHA-384 and SHA-512/256 are simply SHA-512 run with different initial values and truncated output, included specifically so a truncated digest can't be mistaken for (or trivially related to) the full SHA-512 output of the same input.

Privacy

Everything, including the $6$ crypt and the benchmark, runs entirely in your browser. Nothing is uploaded, and no password you test here ever leaves your machine.

FAQ

Frequently asked questions

Is SHA-512 actually faster than SHA-256?
Often, yes, on 64-bit hardware -- SHA-512 operates on 64-bit words that match the CPU's native register width, while SHA-256's 32-bit words leave half of every 64-bit operation unused. Run the benchmark tab on this page to see the real difference on your own browser and hardware.
What is $6$ / SHA-512crypt?
The password-hashing scheme most Linux systems use in /etc/shadow -- not raw SHA-512, but a deliberately slow construction (5,000+ iterations by default) built on top of it, specified by Ulrich Drepper. It predates wider Argon2id/bcrypt adoption and is still common today.
Is it safe to type a real password into the $6$ tool?
Nothing here is sent anywhere -- the entire computation runs in your browser via JavaScript. That said, as a general habit, prefer a throwaway or example password over your actual one on any web tool.
Is raw SHA-512 safe for passwords?
No -- raw SHA-512, like SHA-256, is deliberately fast, which is exactly the wrong property for password storage. SHA-512crypt ($6$) exists specifically because it wraps SHA-512 in a slow, iterated construction; for new systems, Argon2id is the current best-practice recommendation over any SHA-2-based crypt scheme.
What is the difference between SHA-384 and SHA-512?
SHA-384 is SHA-512 run with different initial constants and its output truncated to 384 bits -- the truncation is specifically designed so a SHA-384 digest can't be trivially derived from or related to a SHA-512 digest of the same input.
How is this different from the main Hash Generator?
The main Hash Generator covers nine algorithms side by side for quick comparison. This tool goes deep on SHA-512 specifically: a real SHA-512crypt implementation, a live speed benchmark, and the FIPS 180-4/RFC 4231 self-check -- depth on one algorithm rather than breadth across several.
Is anything I hash, benchmark, or crypt here sent anywhere?
No. Every computation runs entirely in your browser -- this tool has no server component.
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