SHA-3 (512-bit) Hash Generator

What this SHA3-512 generator does

This tool computes the SHA3-512 hash of any text, returning a 512-bit value as 128 hexadecimal characters. It offers the strongest fixed-length SHA-3 output and a structurally distinct alternative to SHA-512 for high-assurance applications.

How it works

SHA3-512 (FIPS 202) is a sponge built on the Keccak-f[1600] permutation. The 1600-bit state is split into a 576-bit rate (72 bytes) and a 1024-bit capacity. The message is padded with the multi-rate rule — append 0x06, pad with zeros, then OR 0x80 into the last byte — and absorbed 72 bytes at a time, applying 24 rounds of the theta, rho, pi, chi, and iota mixing steps on each absorb. The first 512 bits of the final state are squeezed out as the digest. This runs entirely in browser JavaScript using BigInt lane arithmetic.

Why choose SHA3-512 over SHA-512?

The two algorithms produce equally large digests but have fundamentally different internal designs. SHA-512 uses a Merkle-Damgård construction, which is vulnerable to length-extension attacks — an adversary who knows hash(message) can compute hash(message + extra) without knowing the original message. SHA3-512’s sponge construction is immune to this, making it the preferred choice in any protocol where length-extension is a concern, such as when building custom MACs.

From a security-level standpoint, SHA3-512 provides 256-bit collision resistance and 512-bit preimage resistance, identical to SHA-512. The choice often comes down to ecosystem: SHA-512 is more widely supported in older systems, while SHA3-512 is the forward-looking NIST standard (FIPS 202, 2015) with cleaner security proofs.

When to use SHA3-512

• High-assurance data integrity: Signing or fingerprinting extremely sensitive data where you want the widest available SHA-3 digest and immunity to length-extension.
• Protocol design: New cryptographic protocols that benefit from the sponge model’s flexibility — SHA-3 underpins SHAKE128, SHAKE256, and SHA-3 derived XOFs all using the same Keccak core.
• Cross-checking other hashes: When you have an SHA-512 hash from one system and need to verify with a structurally different algorithm before trusting a result.
• Compliance requirements: Some government and financial regulations specify FIPS 202 algorithms; SHA3-512 is one of the four standardized FIPS 202 variants.

Reference examples

Note that hello and Hello produce completely different hashes — the avalanche effect means any single-character change flips roughly half the output bits.

Tips and notes

• SHA3-512 cannot be length-extended, unlike plain SHA-512.
• The smaller rate (72 bytes) means more permutation calls per byte than SHA3-256 (136 bytes), so SHA3-512 is the slowest SHA-3 variant but offers the highest 256-bit security level.
• Because this runs in browser JavaScript, throughput for multi-megabyte inputs is slower than a native implementation. For large files, prefer a CLI tool like openssl dgst -sha3-512 or sha3sum.
• This tool hashes the UTF-8 encoding of the text you enter. If you need to hash raw bytes or a binary file, you need a binary-capable tool.