What is a one-time pad?
A one-time pad combines plaintext with a pre-shared random key stream. For binary data, this is commonly described as XOR. If every key byte is random, secret, and used only once, the ciphertext alone does not reveal which same-length plaintext was sent.
Why this matters
Modern encryption usually depends on computational assumptions: certain problems are believed to be too expensive to solve. Correct one-time-pad secrecy is different. It is information-theoretic, which is why it remains meaningful in post-quantum discussions.
Why every app does not use it
The operational cost is high. A 1 MB file needs 1 MB of fresh key material. Keys must be generated well, exchanged safely, stored securely, tracked accurately, and never reused. ONE exists because the product embraces that operational reality instead of hiding it.
Key consumption
Every encrypted byte consumes one byte of key material. Send 10 KB and roughly 10 KB of key is no longer available. When the key reaches zero, the secure workflow is to create and exchange a new key.
Failure modes
Key reuse is dangerous. Weak randomness, compromised devices, unsafe backups, incorrect offset tracking, or sending the key through a network can invalidate the security model. OneCryption's website should say this plainly because the most security-aware customers are allergic to magical claims.
Sources worth reading
Claude Shannon, Communication Theory of Secrecy Systems
Gilbert Vernam, Secret Signaling System patent