SHA-512 hash generator — 128-character digests and HMAC-SHA512

How to use the SHA-512 hash generator

1. Put your data in Text to hash. The digest updates as you type.
2. In Input is, keep Text (UTF-8) for normal text, or pick Hex bytes or Base64 bytes if you are pasting raw binary in one of those forms.
3. Choose Output: lowercase hex, uppercase HEX, or Base64.
4. To sign a message, enter a secret in HMAC key (optional). The result label changes from SHA-512 to HMAC-SHA-512.
5. Check Digest length (always 512 bits) and Input size in bytes before you copy.

What it does and when to use it

SHA-512 is the 64-bit member of the SHA-2 family defined in FIPS 180-4. It is used where a long, collision-resistant fingerprint is wanted: Linux sha512sum checksums, some package managers, Ed25519 signatures internally, and HMAC-SHA512 signatures on exchange and payment APIs. Use this page to check a test vector or debug an HMAC header that does not verify.

For other members of the family see the SHA-384 generator and the SHA-256 generator. To hash a whole download rather than pasted text, use the file hash calculator, which has a SHA-512 checkbox.

How it works

The tool first turns your input into bytes. Text is encoded as UTF-8, so é becomes the two bytes c3 a9. Hex and Base64 input are decoded straight to bytes, and invalid characters produce an error message instead of a wrong digest.

The bytes go to the hash-wasm library, which runs SHA-512 as WebAssembly in your browser. SHA-512 pads the message to a multiple of 1,024 bits, then runs each block through 80 rounds that mix eight 64-bit state words. The final state is the 512-bit digest. With a key, the same function is wrapped in HMAC (RFC 2104): the key is mixed into an inner and an outer hash so that only someone with the key can produce the result. Nothing is uploaded.

Worked examples

Standard test value. abc gives ddaf35a193617abacc417349ae20413112e6fa4e89a97ea20a9eeee64b55d39a2192992a274fc1a836ba3c23a3feebbd454d4423643ce80e2a9ac94fa54ca49f, the example printed with the SHA-2 standard.

HMAC-SHA512. Text what do ya want for nothing? with key Jefe returns 164b7a7bfcf819e2…a38bce737, which matches test case 2 of RFC 4231.

Text versus bytes. café as UTF-8 text and 636166c3a9 as Hex bytes both report Input size 5 bytes and the same digest, 0c9dac7fe6137191…e3aeb8ce. This is a quick way to prove which bytes your program really hashes.

Limits and tips

• A hash cannot be reversed; lookup sites only guess short or common inputs.
• The HMAC key is always read as UTF-8 text. A hex or Base64 secret must be typed exactly as your code passes it.
• The text box suits pasted data. For files of any size, the file tool reads them in chunks.
• SHA-512 is fine for integrity and signatures, but never as a plain password hash.