CRC64

CRC64 is a type of cyclic redundancy check that uses a 64-bit checksum to detect errors in data. It operates by treating the input as a binary polynomial and performing division by a fixed 64-bit generator polynomial in GF(2). The resulting remainder, the CRC value, is appended to the data or stored alongside it. On receipt or retrieval, the same division is performed; a zero remainder indicates that no detectable errors were introduced, within the capabilities of the algorithm.

There are several standardized variants of CRC64, differing mainly in the choice of generator polynomial and in certain bit-ordering and finalization settings. Two widely referenced variants are CRC-64-ECMA-182 and CRC-64-ISO (also referred to in ITU contexts). CRC-64-ECMA-182 uses the 64-bit polynomial 0x42F0E1EBA9EA3693 and typically adopts non-reflected input and output with no final xor. Other variants use different polynomials and may apply reflection of input bytes, as well as different initial and final XOR values. Because of these differences, implementations are not interchangeable without selecting the same variant.

Computation can be performed with bitwise iteration,, or more efficiently with table-driven methods that store precomputed per-byte remainders. Modern processors may also provide hardware acceleration for CRC64, improving throughput in data-intensive tasks. CRC64 offers stronger error-detection capabilities than CRC32 due to its larger state, reducing the probability of undetected errors in large data blocks; however, like all CRCs, it is not a cryptographic checksum and should not be used for security purposes.

Applications commonly include data integrity verification in storage systems, archival formats, network protocols, and large-scale data transfers where a 64-bit checksum provides a balance between detection strength and resource usage.