Hash / Message Authentication Codes
Compute cryptographic hashes (digests) and message authentication codes (MACs) in your browser. A hash maps any input to a fixed-size fingerprint — SHA-256, SHA-512, SHA-3, BLAKE2 and more — useful for integrity checks, deduplication and commitments. A MAC adds a secret key, so only key-holders can produce or verify the tag, authenticating both integrity and origin.
The MAC picker covers HMAC (over any digest), CMAC (block-cipher based), KMAC (Keccak), Poly1305, GMAC, SipHash and keyed BLAKE2, with adjustable output length for XOFs such as SHAKE. Insecure legacy digests like MD5 and SHA-1 are clearly flagged.
Hashes are one-way and cannot be reversed — there is no “decrypt”. To turn a password into a key, use a slow KDF in the Key Derivation tool rather than a plain hash.
Frequently asked questions
- Can I reverse a hash?
- No — cryptographic hashes are one-way. Identical input always gives identical output, but you cannot recover the input from the digest.
- What is the difference between a hash and a MAC?
- A hash needs no key, so anyone can compute it. A MAC mixes in a secret key, so only someone with the key can produce or verify the tag — proving authenticity, not just integrity.
- Should I hash passwords with SHA-256?
- No. Plain hashes are far too fast for passwords. Use a dedicated password KDF such as Argon2id, scrypt or PBKDF2 in the Key Derivation tool.