This page is a guideline to the use of one-time pads and how to set up one-time pad communications in only four steps. One-time pad encryption is unbreakable if properly applied. However, the security of the system entirely depends on the correct use of the one-time pads and the their secure distribution.
For over 400 years,the problem remained. How could Alice design a cipherthat hides her fingerprint, thus stopping theleak of information? The answer is randomness. Imagine Alice rolleda 26 sided die to generate a longlist of random shifts, and shared this with Bobinstead of a code word. Now, to encrypther message, Alice uses the list ofrandom shifts instead. It is important thatthis list of shifts be as long as the message,as to avoid any repetition. Then she sends it to Bob, whodecrypts the message using the same list of randomshifts she had given him. Now Eve will have a problem,because the resulting encrypted message will havetwo powerful properties. One, the shifts never fallinto a repetitive pattern. And two, the encrypted messagewill have a uniform frequency distribution. Because there is no frequencydifferential and therefore no leak, it is nowimpossible for Eve to break the encryption. This is the strongestpossible method of encryption, and it emerged towards theend of the 19th century. It is now known asthe one-time pad. In order to visualize thestrength of the one-time pad, we must understand thecombinatorial explosion which takes place. For example, the CaesarCipher shifted every letter by the same shift, which wassome number between 1 and 26. So if Alice was toencrypt her name, it would result in one of26 possible encryptions. A small number of possibilities,easy to check them all, known as brute force search. Compare this to the one-timepad, where each letter would be shifted by a differentnumber between 1 and 26. Now think about the numberof possible encryptions. It's going to be 26 multipliedby itself five times, which is almost 12 million. Sometimes it'shard to visualize, so imagine she wrote hername on a single page, and on top of it stackedevery possible encryption. How high do youthink this would be? With almost 12 millionpossible five-letter sequences, this stack of paperwould be enormous, over one kilometer high. When Alice encrypts hername using the one-time pad, it is the same as pickingone of these pages at random. From the perspective ofEve, the code breaker, every five letterencrypted word she has is equally likely tobe any word in this stack. So this is perfectsecrecy in action.