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An ordering problem that is easy to envision occurs when the data word is transferred byte-by-byte between a big-endian system and a little-endian system and the Fletcher-32 checksum is computed. If blocks are extracted from the data word in memory by a simple read of a 16-bit unsigned integer, then the values of the blocks will be different in ...
It is used to validate the integrity of the key or compare keys without knowing their actual values. The KCV is computed by encrypting a block of bytes, each with value '00' or '01', with the cryptographic key and retaining the first 6 hexadecimal characters of the encrypted result.
Parity byte or parity word [ edit ] The simplest checksum algorithm is the so-called longitudinal parity check , which breaks the data into "words" with a fixed number n of bits, and then computes the bitwise exclusive or (XOR) of all those words.
For example, some 16-bit CRC schemes swap the bytes of the check value. Omission of the high-order bit of the divisor polynomial: Since the high-order bit is always 1, and since an n -bit CRC must be defined by an ( n + 1 )-bit divisor which overflows an n -bit register , some writers assume that it is unnecessary to mention the divisor's high ...
Each sequence begins with a one-byte token that is broken into two 4-bit fields. The first field represents the number of literal bytes that are to be copied to the output. The second field represents the number of bytes to copy from the already decoded output buffer (with 0 representing the minimum match length of 4 bytes).
A file signature is data used to identify or verify the content of a file. Such signatures are also known as magic numbers or magic bytes.. Many file formats are not intended to be read as text.
This hash function offsets the bytes 4 bits before adding them together. When the quantity wraps, the high 4 bits are shifted out and if non-zero, xored back into the low byte of the cumulative quantity. The result is a word-size hash code to which a modulo or other reducing operation can be applied to produce the final hash index.
Instead, it returns a 16-byte 128-bit RAW value based on a host identifier and a process or thread identifier, somewhat similar to a GUID. [34] PostgreSQL contains a UUID datatype [35] and can generate most versions of UUIDs through the use of functions from modules. [36] [37] MySQL provides a UUID function, which generates standard version-1 ...