Hashing & Integrity Lab
A checksum only protects you if you actually check it — and if the algorithm still holds. This lab computes real SHA-256, SHA-384 and SHA-512 digests live in your browser with the Web Crypto API. Verify a published hash against what you really received, choose an algorithm you can defend, and find the tampered artifact in a set. You will watch a single flipped digit — or an invisible look-alike letter — change the entire digest, and see exactly why MD5 and SHA-1 are retired.
The real job. More noise, a tighter clock.
Verify integrity like it is your job
Every digest here is computed live in your browser with the Web Crypto API — real SHA-256, SHA-384 and SHA-512 over the exact bytes. You will verify a published checksum, pick a hash algorithm you can defend, and hunt the one tampered artifact in a set. Clear 75% to pass — finish under par for a speed bonus and a better grade.
Live arena
4 activeadversary staging…
Why MD5 & SHA-1 are retired
A hash is broken once two different inputs can be forced to the same digest (a collision). Then a matching checksum proves nothing — an attacker can swap a file for a malicious twin with the identical hash.
Two different inputs, identical MD5 (Wang & Yu, 2004)
d131dd02c5e6eec4693d9a0698aff95c2fcab58712467eab4004583eb8fb7f8955ad340609f4b30283e488832571415a085125e8f7cdc99fd91dbdf280373c5bd8823e3156348f5bae6dacd436c919c6dd53e2b487da03fd02396306d248cda0e99f33420f577ee8ce54b67080a80d1ec69821bcb6a8839396f9652b6ff72a70
d131dd02c5e6eec4693d9a0698aff95c2fcab50712467eab4004583eb8fb7f8955ad340609f4b30283e4888325f1415a085125e8f7cdc99fd91dbd7280373c5bd8823e3156348f5bae6dacd436c919c6dd53e23487da03fd02396306d248cda0e99f33420f577ee8ce54b67080280d1ec69821bcb6a8839396f965ab6ff72a70
79054025255fb1a26e4bc422aef54eb4
Highlighted nibbles are the only differences — same MD5.
Two different PDFs, identical SHA-1 (SHATTERED, 2017)
38762cf7f55934b34d179ae6a4c80cadccbb7f0a
Produced for ~$110k of GPU time in 2017. SHA-1 integrity guarantees are dead.
These digests are bundled, historical facts — nothing here recomputes them. The SHA-* checks in the lab are computed live with Web Crypto.
What this lab is
- A free, browser-based hashing lab: it computes real SHA-256, SHA-384 and SHA-512 digests live with the Web Crypto API over your exact bytes — no server, no upload.
- Verify a published checksum against the file you actually received and decide intact vs. tampered — a one-character, whitespace or homoglyph change flips the whole digest.
- Pick an algorithm you can defend: MD5 and SHA-1 are retired (practical collisions), SHA-256 or stronger is the modern default.
- Spot the single tampered artifact in a set by comparing published and live hashes, not by reading the file.
- A bundled teaching panel shows the famous MD5 (2004) and SHA-1 (SHATTERED, 2017) collision pairs — two different inputs, one digest — as static facts, never recomputed.
Frequently asked questions
What is the Hashing & Integrity Lab?
A free, in-browser training game for cryptographic integrity. It computes real SHA-256, SHA-384 and SHA-512 digests live with the Web Crypto API (crypto.subtle) over the exact bytes you see, then has you verify a published checksum, choose a defensible hash algorithm, and find the one tampered artifact in a set by hash. Everything runs client-side — nothing is uploaded.
Why are MD5 and SHA-1 treated as retired?
Both have practical collisions: two different inputs can be forced to the same digest, so a matching checksum no longer proves a file was not swapped for a malicious twin. MD5 was broken in 2004 and SHA-1 was collided in 2017 (the SHATTERED attack). For integrity and signing, use SHA-256 or stronger. The lab bundles the famous collision pairs as static teaching data and never recomputes them — MD5 is not even in Web Crypto.
Is the hashing real or simulated?
Real. SHA-256/384/512 are computed in your browser with the standard Web Crypto API. You can confirm that changing a single byte — a swapped digit, a trailing space, or an invisible Cyrillic look-alike letter — produces a completely different digest. That avalanche effect is the whole lesson: trust the hash comparison, not how the file looks.
Who is it for?
Engineers and analysts verifying downloads, releases, SBOMs and configs; anyone choosing a checksum or signing algorithm; and people prepping for a security or cloud interview. No account or install needed.