Hash Generator

A cryptographic hash function takes any input and produces a fixed-length output (the hash or digest). It has three key properties: deterministic (same input always produces same output), one-way (you can't reverse a hash to get the input), and collision-resistant (it's computationally infeasible to find two different inputs that produce the same hash).

For new applications: SHA-256 is the default choice. It's fast, widely supported, and still secure. SHA-512 produces a longer hash (512 bits vs 256) for higher security margins. SHA-1 is deprecated for security use — it has known collision attacks — but still appears in legacy systems and Git. Use SHA-256 unless you have a specific reason to choose otherwise.

Everything runs in your browser using the Web Crypto API. No data is sent to any server. However, hashing is not encryption — a SHA-256 hash of a password or secret does not protect it if an attacker has the hash and can try inputs (dictionary attacks). Never hash secrets without a salt and key-stretching function.

That's by design — hashes are deterministic. This property makes them useful for verification: publish a hash, recipient hashes their copy, match means the data is identical. The trade-off is that an attacker can precompute hashes for common inputs (rainbow tables), which is why password storage needs salting.

Hashing is one-way — there's no key and no way to reverse it. Encryption is two-way — you can encrypt and decrypt with the right key. Hash files to verify integrity. Encrypt files to protect content. Confusing the two is a common security mistake (storing password hashes without salt, or 'encrypting' with MD5).