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Mathematics of cyclic redundancy checks. The cyclic redundancy check (CRC) is based on division in the ring of polynomials over the finite field GF (2) (the integers modulo 2), that is, the set of polynomials where each coefficient is either zero or one, and arithmetic operations wrap around. Any string of bits can be interpreted as the ...
A cyclic redundancy check (CRC) is an error-detecting code commonly used in digital networks and storage devices to detect accidental changes to digital data. [1][2] Blocks of data entering these systems get a short check value attached, based on the remainder of a polynomial division of their contents. On retrieval, the calculation is repeated ...
Computation of a cyclic redundancy check is derived from the mathematics of polynomial division, modulo two. In practice, it resembles long division of the binary message string, with a fixed number of zeroes appended, by the "generator polynomial" string except that exclusive or operations replace subtractions.
Usually, the second sum will be multiplied by 2 32 and added to the simple checksum, effectively stacking the sums side-by-side in a 64-bit word with the simple checksum at the least significant end. This algorithm is then called the Fletcher-64 checksum. The use of the modulus 2 32 − 1 = 4,294,967,295 is also generally implied. The rationale ...
Luhn algorithm. The Luhn algorithm or Luhn formula, also known as the " modulus 10" or "mod 10" algorithm, named after its creator, IBM scientist Hans Peter Luhn, is a simple check digit formula used to validate a variety of identification numbers. It is described in US patent 2950048A, granted on 23 August 1960. [1]
up to 2 bits of triplet omitted (cases not shown in table). Though simple to implement and widely used, this triple modular redundancy is a relatively inefficient ECC. Better ECC codes typically examine the last several tens or even the last several hundreds of previously received bits to determine how to decode the current small handful of ...
Barrett reduction. In modular arithmetic, Barrett reduction is a reduction algorithm introduced in 1986 by P.D. Barrett. [ 1 ] A naive way of computing. would be to use a fast division algorithm. Barrett reduction is an algorithm designed to optimize this operation assuming is constant, and , replacing divisions by multiplications.
division/modulo xxHash [8] 32, 64 or 128 bits product/rotation t1ha (Fast Positive Hash) [9] 64 or 128 bits product/rotation/XOR/add GxHash [10] 32, 64 or 128 bits AES block cipher pHash [11] fixed or variable see Perceptual hashing: dhash [12] 128 bits see Perceptual hashing: SDBM [2] [13] 32 or 64 bits mult/add or shift/add also used in GNU ...