Method and apparatus for verifying a value for a batch of items

Abstract

A method and apparatus for verifying a total value for a batch of items, and particularly a total postage value for a batch of mail pieces. A batch of mail is prepared in a conventional manner in accordance with information generated by a data processing system. The information is also provided to a secure manifest system which generates an output to be marked on each item. The manifest system determines a particular value for each item and generates a message identifying the entire batch. The message is encrypted and expressed as k ordered numbers. The ordered numbers are taken as parameters of a function f(x)=a.sub.o +a.sub.1x +. . . a.sub.k-1 x.sup.k-1 mod p. A unique arbitrary value, x.sub.i, is selected for each item and a value f of x.sub.i is determined. Each item is then marked with indicia including the postage value v.sub.i, x.sub.i, and f(x.sub.i). A party may then sample the batch to obtain k items, determine the parameters, a, from k ordered pairs x.sub.i, f(x.sub.i), decrypt the message and verify the postage value, V. Where the batch includes a number of classes the values, x.sub.i, for each class may be chosen to be members of the same class of congruent residues. A second function g.sub.j (x.sub.i) may then be computed to identify each class and tested in the manner described above. Further assurance is provided by testing each value, x.sub.i, to assure that for a given class, each value, x.sub.i, is of the same class of congruent residues.