CRC8

CRC8 is a type of cyclic redundancy check that produces an 8-bit checksum used to detect errors in digital data. It is commonly used to verify the integrity of small messages in communications and storage systems.

CRC8 treats the data as a polynomial over the finite field GF(2). A fixed generator polynomial of degree 8 is used to divide the data polynomial; the remainder, expressed as 8 bits, is the CRC value.

In practice, CRC-8 implementations are defined by four parameters: the generator polynomial, the initial remainder, whether input and output are bit-reflected, and a final xor value. Several variants exist. The polynomial 0x07 is a common default for general-purpose CRC-8, while other variants such as 0x31 and 0x1D are used in specific standards and devices (for example, some Maxim/Dallas parts and SAE-J1850).

Computing the CRC can be done bit by bit or with a precomputed lookup table of 256 entries for speed. The calculation is linear in the number of data bytes and requires only a small amount of memory for the table.

CRC-8 provides a lightweight error-detection mechanism suitable for short frames, but its 8-bit width limits its ability to detect all error patterns, especially long sequences of errors. It is typically used where resource constraints favor simplicity over stronger checks provided by higher-width CRCs.