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For example where denotes the exclusive disjunction (XOR) operation. [2] This operation is sometimes called modulus 2 addition (or subtraction, which is identical). [ 3 ] With this logic, a string of text can be encrypted by applying the bitwise XOR operator to every character using a given key.
The four-square cipher is a manual symmetric encryption technique. [1] It was invented by the French cryptographer Felix Delastelle.. The technique encrypts pairs of letters (digraphs), and falls into a category of ciphers known as polygraphic substitution ciphers.
In the history of cryptography, the Nihilist cipher is a manually operated symmetric encryption cipher, originally used by Russian Nihilists in the 1880s to organize terrorism against the tsarist regime. The term is sometimes extended to several improved algorithms used much later for communication by the First Chief Directorate with its spies.
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 ...
With the Caesar cipher, encrypting a text multiple times provides no additional security. This is because two encryptions of, say, shift A and shift B, will be equivalent to a single encryption with shift A + B. In mathematical terms, the set of encryption operations under each possible key forms a group under composition. [26]
For example, "UQJHSE" could be the code for "Proceed to the following coordinates." When using a cipher the original information is known as plaintext , and the encrypted form as ciphertext . The ciphertext message contains all the information of the plaintext message, but is not in a format readable by a human or computer without the proper ...
In this decryption example, the ciphertext that will be decrypted is the ciphertext from the encryption example. The corresponding decryption function is D(y) = 21(y − b) mod 26, where a −1 is calculated to be 21, and b is 8. To begin, write the numeric equivalents to each letter in the ciphertext, as shown in the table below.
As above, let be the length of the string to be decrypted and let be the number of rails used during encryption. We will add two variables, x {\displaystyle x} and y {\displaystyle y} , where x + 1 {\displaystyle x+1} = the number of diagonals in the decrypted Rail Fence, and y {\displaystyle y} = the number of empty spaces in the last diagonal.