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In cryptography, ciphertext or cyphertext is the result of encryption performed on plaintext using an algorithm, called a cipher. [1] Ciphertext is also known as encrypted or encoded information because it contains a form of the original plaintext that is unreadable by a human or computer without the proper cipher to decrypt it.
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 mechanism to decrypt it. The operation of a cipher usually depends on a piece of auxiliary information, called a key (or, in traditional NSA parlance, a cryptovariable ).
Padding a message's payload before encrypting it can help obscure the cleartext's true length, at the cost of increasing the ciphertext's size and introducing or increasing bandwidth overhead. Messages may be padded randomly or deterministically, with each approach having different tradeoffs.
For instance, if all occurrences of the letter e turn into the letter X, a ciphertext message containing numerous instances of the letter X would suggest to a cryptanalyst that X represents e. The basic use of frequency analysis is to first count the frequency of ciphertext letters and then associate guessed plaintext letters with them.
This can be achieved, for instance, through the utilization of the chi-squared statistic [22] or by minimizing the sum of squared errors between the observed and known language distributions. [23] The unicity distance for the Caesar cipher is about 2, meaning that on average at least two characters of ciphertext are required to determine the ...
A method of language teaching characterized by translation and the study of grammar rules. Involves presentation of grammatical rules, vocabulary lists, and translation. Emphasizes knowledge and use of language rules rather than communicative competence. This method of language teaching was popular in the 20th century until the early 1960s.
Partially solved (all 4 ciphertexts solved between 1985 and 1986, but the solution to the 4th ciphertext has since been lost) [2] 1987 Decipher III: Unsolved [2] 1990 Kryptos: Partially solved (3 out of the 4 ciphertexts solved between 1992 and 1999) 1991 Scorpion ciphers [3] Unsolved 1999 Ricky McCormick's encrypted notes: Unsolved 2006
In colloquial use, the term "code" is often used to mean any method of encryption or concealment of meaning. However, in cryptography, code has a more specific meaning: the replacement of a unit of plaintext (i.e., a meaningful word or phrase) with a code word (for example, "wallaby" replaces "attack at dawn"). A cypher, in contrast, is a ...