  Checksum algorithms are widely employed due to their use of a simple
algorithm with fast computational speed to provide a basic detection capability
for corrupted data. This paper describes the benefits of adding the design
parameter of increased data block size for modular addition checksums, combined
with an empirical approach to modulus selection. A longer processing block size
with the right modulus can provide significantly better fault detection
performance with no change in the number of bytes used to store the check
value. In particular, a large-block dual-sum approach provides Hamming Distance
3-class fault detection performance for many times the data word length
capability of previously studied Fletcher and Adler checksums. Moduli of 253
and 65525 are identified as being particularly effective for general-purpose
checksum use.
