CRYPTO LABThe light-pulse delivery service
Quantum
Courier.
A little light. A long journey.
Can you trust what arrives?
Receiver calibration
Orange: disclosed sample. Mint: remaining candidate bits.
The model: Eve intercepts and resends every pulse, choosing each basis independently with equal probability. In an otherwise ideal, noiseless channel, each sifted bit has a 1 in 4 error chance. For t independent samples, detection = 1 − (3/4)t. This is the chance of finding at least one error under that attack, not the chance your channel is safe.
Flight cleared.
A route worth remembering
You earned your wings.
Find your next gameTry an experimentThe light bench
Prepare 64 fresh, identical simulated photons. What happens when you turn the receiver?
Make a prediction, then send a batch.
Same basis: the prepared bit every time. Different basis: an equal chance of 0 or 1 on each fresh photon, not necessarily an even split in a batch. This classical simulation uses browser random numbers; it is not quantum hardware.
Look a little deeperWhy this works
The + and × symbols represent two polarization measurement bases. Each has two states, which we call 0 and 1. Measuring in the other basis produces an unpredictable result and prepares a new state.
In BB84, Alice sends random states. Bob makes independent basis choices before Alice announces hers. They keep matching positions, disclose a sample, and use authenticated public discussion to assess errors and process the remaining bits.
What this game simplifies: perfect single photons, no loss, ideal detectors, and a simple intercept/resend attack. The teaching replays deliberately contain eight matches out of twelve and selected outcomes. They are not frequency experiments. The game’s “pause on any error” rule is a conservative puzzle rule, not a practical QKD threshold.
A full system needs an authenticated classical channel, finite-size security analysis, error correction and privacy amplification. None is implemented here. QKD establishes key material; it does not send a secret message in these light pulses.
Bennett & Brassard’s original BB84 paper (1984)
Shor & Preskill’s security proof (2000)
Flight badges, daily routes, and saved progress
Each flight starts at 3 badges. An incorrect submission costs one; using a hint costs one once per flight. You always earn at least 1 for completing a flight. Restart for a fresh attempt. Your best score for each of six flights is saved in this browser, up to 18.
The daily route has three tasks and one shared score out of 3. It changes at midnight UTC and uses a public date seed to make the same teaching puzzle for everyone. This seed is not cryptographic randomness. A route you already started keeps its date. Only your most recently completed daily date and best score are saved.
Progress stays in this browser. No account or uploads.