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One example of deniable encryption is a cryptographic filesystem that employs a concept of abstract "layers", where each layer can be decrypted with a different encryption key. [ citation needed ] Additionally, special " chaff layers" are filled with random data in order to have plausible deniability of the existence of real layers and their ...
The OAEP algorithm is a form of Feistel network which uses a pair of random oracles G and H to process the plaintext prior to asymmetric encryption. When combined with any secure trapdoor one-way permutation f {\displaystyle f} , this processing is proved in the random oracle model to result in a combined scheme which is semantically secure ...
To support such deniable encryption systems, a few cryptographic algorithms are specifically designed to make ciphertext messages indistinguishable from random bit strings. [4] [5] [6] Most applications don't require an encryption algorithm to produce encrypted messages that are indistinguishable from random bits.
The term "probabilistic encryption" is typically used in reference to public key encryption algorithms; however various symmetric key encryption algorithms achieve a similar property (e.g., block ciphers when used in a chaining mode such as CBC), and stream ciphers such as Freestyle [1] which are inherently random.
Since each output bit changes with the 50% probability, about half of the output bits will actually change with an input bit change (cf. Strict avalanche criterion). [ 1 ] A P-box is a permutation of all the bits: it takes the outputs of all the S-boxes of one round, permutes the bits, and feeds them into the S-boxes of the next round.
In an ideal cipher, any linear equation relating plaintext, ciphertext and key bits would hold with probability 1/2. Since the equations dealt with in linear cryptanalysis will vary in probability, they are more accurately referred to as linear approximations. The procedure for constructing approximations is different for each cipher.
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 ...
The variable p represents the probability that a collision will occur—that is, the probability that two or more inputs (balls) will be assigned the same output (bin). In a birthday attack, p is often set to 0.5 (50%) to estimate how many inputs are needed to have a 50% chance of a collision.