Generate and verify checksums safely
A cryptographic hash maps input data to a fixed-length digest. Even a one-byte change produces a different result, making hashes useful for integrity checks, cache keys, digital-signature workflows and identifying duplicate data.
SHA-256 and SHA-512 remain appropriate for general integrity verification. MD5 and SHA-1 are retained for legacy checksums only.
HMAC combines a secret key with a hash so recipients can verify integrity and authenticity when they share the key.
Fast general-purpose hashes are unsuitable for password databases. Use a salted password KDF such as Argon2, scrypt or bcrypt.
How to use the hash generator
- Choose text input or select a local file.
- Select hexadecimal or Base64 output and enable HMAC only when a shared secret is required.
- Click Calculate hashes to generate all digests.
- Paste a published checksum to see whether one of the calculated results matches.
Algorithm guidance
MD5 and SHA-1 have known collision weaknesses and should not be used for new security designs. A matching legacy checksum can still detect ordinary download corruption, but it does not prove authenticity when an attacker can replace both the file and checksum.
Frequently Asked Questions
Does ZeeSharp upload the file I hash?
No. The selected file is read and hashed by your browser. Only a generic tool-usage event is recorded when you press Calculate.
Why does the same text sometimes produce a different hash elsewhere?
Encoding and invisible characters matter. A trailing newline, different Unicode normalization or UTF-8 versus another encoding changes the underlying bytes and therefore the digest.
What is the difference between a hash and HMAC?
A plain hash uses only the message. HMAC also uses a secret key, allowing someone with the same key to verify that the message and signature belong together.
Can a cryptographic hash be reversed?
Hashes are designed as one-way functions. However, weak or predictable inputs can still be discovered through guessing and lookup tables, which is why plain hashing is not adequate password protection.