One-Time Pad Generator

## What the One-Time Pad Does The one-time pad (OTP) is the only cipher with mathematically proven perfect secrecy. This tool generates a random key and XORs it against your plaintext: each plaintext bit is combined with a key bit, producing ciphertext that — absent the key — is consistent with every possible message of the same length. ## Why It Is Unbreakable (Under Strict Rules) Claude Shannon proved that XOR with a truly random key as long as the message leaks zero information about the plaintext. But that proof rests on three conditions, and breaking any one collapses the security: - **The key must be truly random.** A key from a predictable pseudo-random generator is only as strong as that generator — it is no longer information-theoretically secure. - **The key must be as long as the message.** Stretching a short key (repeating it) turns the OTP into a Vigenère cipher, which falls to frequency analysis. - **The key must never be reused.** Reuse is the classic, fatal mistake: XOR two ciphertexts encrypted with the same key and the keys cancel, leaving the two plaintexts XORed together — often enough to recover both. That is why it is a *one-time* pad. ## The Practical Catch OTP is provably secure but rarely practical: you must securely distribute as much truly random key material as you will ever send. Key distribution is the hard part — if you can move a long secret key safely, you could often just move the message. This is why modern systems use shorter keys with algorithms like AES instead. ## When to Use It - Teaching perfect secrecy and the role of randomness and key reuse. - CTF and puzzle work involving XOR. - Understanding why "unbreakable" depends entirely on operational discipline. Key generation and XOR run entirely in your browser — your plaintext and key are never uploaded.