These codebooks provided little or no security. Such codebooks were commonly used, mainly to reduce telegraph costs by compressing words and phrases into short number-codes or letter-codes.
ONE TIME PAD SYSTEM CODE
The story of one-time pad starts in 1882, when the Californian banker Frank Miller compiles his “Telegraphic Code to Insure Privacy and Secrecy in the Transmission of Telegrams”. Small one-time keys are by no means unbreakable, because the security of the encryption depends on the crypto algorithm they are used for. Such one-time keys, limited in size, are only valid for a single encryption session by some crypto-algorithm under control of that key. Important note: one-time pads or one-time encryption is not to be confused with one-time keys (OTK) or one-time passwords (sometimes also denoted as OTP). There should only be two copies of the key: one for the sender and one for the receiver (some exceptions exist for multiple receivers).Each key is used only once, and both sender and receiver must destroy their key after use.Key and plaintext are calculated modulo 10 (digits), modulo 26 (letters) or modulo 2 (binary).The key is truly random (not generated by a simple computer function or such).The key is at least as long as the message or data that must be encrypted.However, if only one of these rules is disregarded, the cipher is no longer unbreakable. Even infinite computational power and infinite time cannot break one-time pad encryption, simply because it is mathematically impossible. If these rules are applied correctly, the one-time pad can be proven unbreakable (see Claude Shannon’s “Communication Theory of Secrecy Systems”). We can only talk about one-time pad if some important rules are followed. Whatever technological progress may come in the future, one-time pad encryption is, and will remain, the only truly unbreakable system that provides real long-term message secrecy. Used by Special Operations teams and resistance groups during WW2, popular with intelligence agencies and their spies during the Cold War and beyond, protecting diplomatic and military message traffic around the world for many decades, the one-time pad gained a reputation as a simple yet solid encryption system with an absolute security which is unmatched by today’s modern crypto algorithms. It is the only existing mathematically unbreakable encryption. The One-time pad One-time pad (OTP), also called Vernam-cipher or the perfect cipher, is a crypto algorithm where plaintext is combined with a random key.
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