DicipheredTextSpecialCharacters.txt

shared memory multiprocessors are widely accepted in many areas of computing today because they provide costeffective solutions for performancecdemanding applications. a large number of super computers fall in this category, as well as numerous smpcbased commercial servers. however, fundamental differences between parallel and se$uential processing make programming for multiprocessors inherently difficult. programmers reason about the possible results of execution by reasoning about the ordering of the shared memory accesses. while that ordering is trivially wellcdefined at the hardware level on a unicprocessor machine, it is not the case on a machine with multiple processors, or a unicprocessor machine running a multicthreaded program. different processors might see different orderings between a pair of shared memory accesses, and if this is overlooked by the compiler or the programmer, the result of the execution is at worst wrong, and at best difficult to understand.  codes generally substitute different length strings of characters in the output, while ciphers generally substitute the same number of characters as are input. there are exceptions and some cipher systems may use slightly more, or fewer, characters when output versus the number that were input.  codes operated by substituting according to a large codebook which linked a random string of characters or numbers to a word or phrase. for example, "u$,hse" could be the code for "proceed to the following coordinatesp" 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 mechanism to decrypt it.  the operation of a cipher usually depends on a piece of auxiliary information, called a key ror, in traditional nsa parlance, a cryptovariables. the encrypting procedure is varied depending on the key, which changes the detailed operation of the algorithm. a key must be selected before using a cipher to encrypt a message. without knowledge of the key, it should be extremely difficult, if not impossible, to decrypt the resulting ciphertext into readable plaintext.  most modern ciphers can be categori[ed in several ways  by whether they work on blocks of symbols usually of a fixed si[e rblock cipherss, or on a continuous stream of symbols rstream cipherss. by whether the same key is used for both encryption and decryption rsymmetric key algorithmss, or if a different key is used for each rasymmetric key algorithmss. if the algorithm is symmetric, the key must be known to the recipient and sender and to no one else. if the algorithm is an asymmetric one, the enciphering key is different from, but closely related to, the deciphering key. if one key cannot be deduced from the other, the asymmetric key algorithm has the public/private key property and one of the keys may be made public without loss of confidentiality.