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Stream ciphers are defined as using plain text digits that are combined with a pseudorandom cipher digit stream. Stream ciphers are typically faster than block ciphers and may have lower hardware complexity, but may be more susceptible to attacks.
When the keystream is generated by a pseudo-random number generator, the result is a stream cipher. With a key that is truly random, the result is a one-time pad, which is unbreakable in theory. The XOR operator in any of these ciphers is vulnerable to a known-plaintext attack, since plaintext ciphertext = key. It is also trivial to flip ...
The two building blocks of the construction, the algorithms Poly1305 and ChaCha20, were both independently designed, in 2005 and 2008, by Daniel J. Bernstein. [2] [3]In March 2013, a proposal was made to the IETF TLS working group to include Salsa20, a winner of the eSTREAM competition [4] to replace the aging RC4-based ciphersuites.
In cryptography, a substitution cipher is a method of encrypting in which units of plaintext are replaced with the ciphertext, in a defined manner, with the help of a key; the "units" may be single letters (the most common), pairs of letters, triplets of letters, mixtures of the above, and so forth.
The attacker can then replace that text by any other text of exactly the same length, such as "three thirty meeting is cancelled, stay home". The attacker's knowledge of the one-time pad is limited to this byte length, which must be maintained for any other content of the message to remain valid.
In cryptography, a salt is random data fed as an additional input to a one-way function that hashes data, a password or passphrase. [1] Salting helps defend against attacks that use precomputed tables (e.g. rainbow tables), by vastly growing the size of table needed for a successful attack.
To generate the keystream, the cipher makes use of a secret internal state which consists of two parts: A permutation of all 256 possible bytes (denoted "S" below). Two 8-bit index-pointers (denoted "i" and "j"). The permutation is initialized with a variable-length key, typically between 40 and 2048 bits, using the key-scheduling algorithm (KSA).
The weaker version generated the additive from the text of a novel or similar book (at least one Rote Kapelle member used The Good Soldier Schweik) This text was converted to a digital additive using a technique similar to a straddling checkerboard. The ultimate development along these lines was the VIC cipher, used in the 1950s by Reino ...