Patent ID: 8306954

Claim:
A computer implemented method for comparing data of a first and a revised version of a file to determine differences between the versions, comprising: segmenting the first and the revised versions into blocks of digital data of equal size; moving a reference frame of a set resolution across adjacent portions of one of the blocks of the revised version the set resolution of the reference frame being a number of bits less than a number of bits defining the equal size of the blocks of digital data; obtaining plural coarse signatures of the one of the blocks of the revised version based on said moving the reference frame across adjacent portions of the one of the blocks of the revised version, the set resolution of the reference frame defining the coarse signatures; comparing each of the plural coarse signatures of the one of the blocks of the revised version to a coarse signature of a comparable one of the blocks of the first version; determining whether any of the plural coarse signatures of the one of the blocks of the revised version matches the coarse signature of the comparable one of the blocks of the first version based on said comparing; and in response to determining none of the plural coarse signatures of the one of the blocks of the revised version match the coarse signature of the comparable one of the blocks of the first version, repeating said moving the reference frame across adjacent portions of one of the blocks of the revised version, obtaining plural coarse signatures of the one of the blocks of the revised version based on said moving, comparing each of the plural coarse signatures of the one of the blocks of the revised version to the coarse signature of the comparable one of the blocks of the first version, and determining whether any of the plural coarse signatures of the one of the blocks of the revised version matches the coarse signature of the comparable one of the blocks of the first version based on said comparing.