Patent ID: 7945544

Claim:
A computer-implemented method, the method comprising: (A) for a first data item comprising a first plurality of parts, (a1) applying a first function to each part of said first plurality of parts to obtain a corresponding part value for each part of said first plurality of parts, wherein each part of said first plurality of parts comprises a corresponding sequence of bits, and wherein the part value for each particular part of said first plurality of parts is based, at least in part, on the corresponding bits in the particular part, and wherein two identical parts will have the same part value as determined using said first function, wherein said first function comprises a first hash function; and (a2) obtaining a first value for the first data item, said first value obtained by applying a second function to the part values of said first plurality of parts of said first data item, said second function comprising a second hash function; (B) for a second data item comprising a second plurality of parts, (b1) applying said first function to each part of said second plurality of parts to obtain a corresponding part value for each part of said second plurality of parts, wherein each part of said second plurality of parts consists of a corresponding sequence of bits, and wherein the part value for each particular part of said second plurality of parts is based, at least in part, on the corresponding bits in the particular part of the second plurality of parts; and (b2) obtaining a second value for the second data item by applying said second function to the part values of said second plurality of parts of said second data item; and (C) ascertaining whether or not said first data item corresponds to said second data item based, at least in part, on said first value and said second value.