SHA-256 (Secure Hash Algorithm 256-bit) is part of the SHA-2 family and produces a 256-bit (64 hex character) hash. It is widely used in security protocols, digital signatures, and blockchain. This tool uses the browser's built-in Web Crypto API — your data never leaves your device.
SHA-256 produces a 256-bit digest using the Merkle-Damgård construction with a Davies-Meyer compression function operating on 32-bit words. It is the workhorse of modern integrity checking — used in TLS certificates, code signing, container image digests, Bitcoin block headers, and content-addressed storage. The 128-bit collision resistance is comfortably beyond brute-force for the foreseeable future.
This calculator uses the browser's Web Crypto API directly, so the 64-character hex string you see matches openssl dgst -sha256, sha256sum, and Python's hashlib byte-for-byte. Non-ASCII input is encoded as UTF-8 before hashing.
Yes — as of 2026 there are no published practical attacks on SHA-256. It provides 128-bit collision resistance and 256-bit preimage resistance, which is well beyond any feasible brute force, and it remains the default in TLS, code signing and Bitcoin.
They share the goal — a 256-bit cryptographic hash — but use completely different internals. SHA-256 uses the Merkle-Damgård construction with a Davies-Meyer compression function; SHA-3 (Keccak) uses a sponge construction. SHA-3 is not a replacement; both are NIST-approved.
No. SHA-256 is a one-way function — there is no key and no decoding step. Any service offering to "reverse a SHA-256 hash" is doing a brute-force or dictionary lookup against precomputed common inputs.
Determinism is a defining property of cryptographic hash functions. The compression function has no random or time-dependent state, so the same byte sequence always maps to the same 256-bit output — the basis for content-addressing systems like git, IPFS and Bitcoin.
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