Search results
Results from the WOW.Com Content Network
So, 6 is a perfect number because the proper divisors of 6 are 1, 2, and 3, and 1 + 2 + 3 = 6. [2] [4] There is a one-to-one correspondence between the Mersenne primes and the even perfect numbers, but it is unknown whether there exist odd perfect numbers. This is due to the Euclid–Euler theorem, partially proved by Euclid and completed by ...
Jean Argles (1925–2023), British code breaker in World War II; Arne Beurling (1905–1986), Swedish mathematician and cryptographer. Lambros D. Callimahos, US, NSA, worked with William F. Friedman, taught NSA cryptanalysts. Ann Z. Caracristi, US, SIS, solved Japanese Army codes in World War II, later became deputy director of National ...
In the asymptotic setting, a family of deterministic polynomial time computable functions : {,} {,} for some polynomial p, is a pseudorandom number generator (PRNG, or PRG in some references), if it stretches the length of its input (() > for any k), and if its output is computationally indistinguishable from true randomness, i.e. for any probabilistic polynomial time algorithm A, which ...
In number theory, a perfect number is a positive integer that is equal to the sum of its positive proper divisors, that is, divisors excluding the number itself. For instance, 6 has proper divisors 1, 2 and 3, and 1 + 2 + 3 = 6, so 6 is a perfect number. The next perfect number is 28, since 1 + 2 + 4 + 7 + 14 = 28.
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, "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 ...
In the above example, the code group, 1001, 1002, 1003, might occur more than once and that frequency might match the number of times that ABC occurs in plain text messages. (In the past, or in non-technical contexts, code and cipher are often used to refer to any form of encryption ).
The problem in the running code was discovered in 1995 by Ian Goldberg and David Wagner, [4] who had to reverse engineer the object code because Netscape refused to reveal the details of its random number generation (security through obscurity). That RNG was fixed in later releases (version 2 and higher) by more robust (i.e., more random and so ...
For example, suppose that the plaintext to be encrypted is attackatdawn. The person sending the message chooses a keyword and repeats it until it matches the length of the plaintext, for example, the keyword "LEMON": LEMONLEMONLE. Each row starts with a key letter. The rest of the row holds the letters A to Z (in shifted order).