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Lattice problem. In computer science, lattice problems are a class of optimization problems related to mathematical objects called lattices. The conjectured intractability of such problems is central to the construction of secure lattice-based cryptosystems: lattice problems are an example of NP-hard problems which have been shown to be average ...
Lattice-based cryptography is the generic term for constructions of cryptographic primitives that involve lattices, either in the construction itself or in the security proof. Lattice-based constructions support important standards of post-quantum cryptography. [ 1] Unlike more widely used and known public-key schemes such as the RSA, Diffie ...
In computing, a linear-feedback shift register ( LFSR) is a shift register whose input bit is a linear function of its previous state. The most commonly used linear function of single bits is exclusive-or (XOR). Thus, an LFSR is most often a shift register whose input bit is driven by the XOR of some bits of the overall shift register value.
XOR cipher. In cryptography, the simple XOR cipher is a type of additive cipher, [ 1] an encryption algorithm that operates according to the principles: A 0 = A, A A = 0, A B = B A, (A B) C = A (B C), (B A) A = B 0 = B, For example where denotes the exclusive disjunction (XOR) operation. [ 2] This operation is sometimes called modulus 2 ...
Bacon's cipher or the Baconian cipher is a method of steganographic message encoding devised by Francis Bacon in 1605. [ 1][ 2][ 3] A message is concealed in the presentation of text, rather than its content. Baconian ciphers are categorized as both a substitution cipher (in plain code) and a concealment cipher (using the two typefaces).
In cryptanalysis, frequency analysis (also known as counting letters) is the study of the frequency of letters or groups of letters in a ciphertext. The method is used as an aid to breaking classical ciphers . Frequency analysis is based on the fact that, in any given stretch of written language, certain letters and combinations of letters ...
Generally, the basic security of cryptographic hash functions can be seen from different angles: pre-image resistance, second pre-image resistance, collision resistance, and pseudo-randomness. Pre-image resistance: given a hash it should be hard to find any message such that . This concept is related to that of the one-way function.
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 receiver deciphers the text by performing ...