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The Aristocrat Cipher is a type of monoalphabetic substitution cipher in which plaintext is replaced with ciphertext and encoded into assorted letters, numbers, and symbols based on a keyword. The formatting of these ciphers generally includes a title, letter frequency, keyword indicators, and the encoder's nom de plume . [ 1 ]
Edgar Allan Poe's "The Gold-Bug" and Sir Arthur Conan Doyle's Sherlock Holmes tale "The Adventure of the Dancing Men" are examples of stories which describe the use of frequency analysis to attack simple substitution ciphers. The cipher in the Poe story is encrusted with several deception measures, but this is more a literary device than ...
The affine cipher is a type of monoalphabetic substitution cipher, where each letter in an alphabet is mapped to its numeric equivalent, encrypted using a simple mathematical function, and converted back to a letter. The formula used means that each letter encrypts to one other letter, and back again, meaning the cipher is essentially a ...
The previous examples were all examples of monoalphabetic substitution ciphers, where just one cipher alphabet is used. It is also possible to have a polyalphabetic substitution cipher, where multiple cipher alphabets are used. The encoder would make up two or more cipher alphabets using whatever techniques they choose, and then encode their ...
The table below shows the support of various stream ciphers. Stream ciphers are defined as using plain text digits that are combined with a pseudorandom cipher digit stream. Stream ciphers are typically faster than block ciphers and may have lower hardware complexity, but may be more susceptible to attacks.
For example, the character A is mapped to p, while a is mapped to 2. The use of a larger alphabet produces a more thorough obfuscation than that of ROT13; for example, a telephone number such as +1-415-839-6885 is not obvious at first sight from the scrambled result Z'\c`d\gbh\eggd. On the other hand, because ROT47 introduces numbers and ...
Classical ciphers are typically vulnerable to known-plaintext attack. For example, a Caesar cipher can be solved using a single letter of corresponding plaintext and ciphertext to decrypt entirely. A general monoalphabetic substitution cipher needs several character pairs and some guessing if there are fewer than 26 distinct pairs.
The Atbash cipher is a particular type of monoalphabetic cipher formed by taking the alphabet (or abjad, syllabary, etc.) and mapping it to its reverse, so that the first letter becomes the last letter, the second letter becomes the second to last letter, and so on. For example, the Hebrew alphabet would work like this: