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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 ...
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.
In 2001, Barak et al., showing that black-box obfuscation is impossible, also proposed the idea of an indistinguishability obfuscator, and constructed an inefficient one. [8] [7] [2] Although this notion seemed relatively weak, Goldwasser and Rothblum (2007) showed that an efficient indistinguishability obfuscator would be a best-possible obfuscator, and any best-possible obfuscator would be ...
For CFB-8, an all-zero IV and an all-zero plaintext, causes 1/256 of keys to generate no encryption, plaintext is returned as ciphertext. [10] For OFB-8, using all zero initialization vector will generate no encryption for 1/256 of keys. [11] OFB-8 encryption returns the plaintext unencrypted for affected keys.
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.
Rather, in a good S-box each output bit will be affected by every input bit. More precisely, in a good S-box each output bit will be changed with 50% probability by every input bit. 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 ...
For example, with the current S-box AES emits no fixed differential with a probability higher than (4/256) 50 or 2 −300 which is far lower than the required threshold of 2 −128 for a 128-bit block cipher. This would have allowed room for a more efficient S-box, even if it is 16-uniform the probability of attack would have still been 2 −200.
A book cipher is a cipher in which each word or letter in the plaintext of a message is replaced by some code that locates it in another text, the key. A simple version of such a cipher would use a specific book as the key, and would replace each word of the plaintext by a number that gives the position where that word occurs in that book.