SHA1 Hash Generator

What is SHA-1?

SHA-1 produces a 160-bit digest for any input: 20 raw bytes, or 40 lowercase hexadecimal characters. Hash typed text or uploaded files and get both forms back.

Why it is treated as legacy

SHA-1's collision resistance is broken. Two different inputs can be constructed to produce the same digest, which destroys the property that signatures and certificates depend on.

The retreat was gradual and well documented. NIST deprecated SHA-1 in 2011, disallowed it for digital signatures after 2013, and has been transitioning away from its remaining uses since. Plenty of deployed systems still emit SHA-1 values, which is why computing one remains a real need.

Are there alternatives?

For anything new, BLAKE3, SHA256, SHA3, BLAKE2b, and BLAKE2s are all appropriate and unbroken.

Use SHA-1 only where an existing format or protocol specifically requires it, never for new signatures, certificates, password storage, or any security-sensitive design.

Fun facts and more info

The digest is always 160 bits no matter how large the input is. Hashing runs one way, so it is not encryption and cannot be reversed.

Broken collision resistance does not mean broken everywhere. Nobody can currently take a SHA-1 digest and find an input that produces it, so the attacks that matter involve an adversary crafting both inputs themselves. That distinction is exactly why signatures had to go first while some legacy uses linger on.