Understanding Cryptographic Hashes
A Hash Function takes an input (or 'message') and returns a fixed-size string of bytes. The output, often called the 'digest' or 'checksum', is unique to that specific input. Even a tiny change in the input (like changing one letter) produces a completely different hash.
Common Algorithms
SHA-256 (Secure Hash Algorithm 2)
The industry standard for security. Used in Bitcoin, SSL certificates, and secure password storage. It produces a 256-bit (64-character) signature.
MD5 (Message Digest 5)
Fast but older. Considered insecure for passwords due to collision vulnerabilities, but still widely used for file integrity checks (checksums).
Why use File Hashing?
When you download software from the internet, how do you know the file wasn't tampered with by a hacker? Developers provide a Checksum (usually SHA-256) on their website.
By uploading the file to this tool, you can generate its hash and paste the developer's checksum into the "Verify Checksum" box. If they match, the file is authentic and safe to run.
What is HMAC?
HMAC (Hash-based Message Authentication Code) is a mechanism for calculating a message authentication code involving a cryptographic hash function in combination with a secret cryptographic key. It allows you to verify both the integrity and the authenticity of a message.