checksum

storage, communications A computed value which depends on

the contents of a block of data and which is transmitted or

stored along with the data in order to detect corruption of

the data. The receiving system recomputes the checksum based

upon the received data and compares this value with the one

sent with the data. If the two values are the same, the

receiver has some confidence that the data was received

correctly.

The checksum may be 8 bits (modulo 256 sum), 16, 32, or some

other size. It is computed by summing the bytes or words of

the data block ignoring overflow. The checksum may be

negated so that the total of the data words plus the checksum

is zero.

Internet packets use a 32-bit checksum.

See also digital signature, cyclic redundancy check.

(1996-03-01)