Patent ID: 8381062

Claim:
A method of storing a file for subsequent proof of recoverability, comprising: sending a file to an archive server, the file having file segments; identifying a set of validation segments from the file segments, the set of validation segments including one or more subsets of the set of validation segments for verifying recoverability of the file on the archive server; determining, for each of the one or more subsets of the set of validation segments, recoverability attributes applicable to the subset of the set of validation segments; defining a validation function, the validation function responsive to a challenge for computing validation values, the validation values for comparison with corresponding recoverability attributes based on a particular subset of the set of validation segments from which the recoverability attributes were derived, the validation function such that substantial computational resources are required to determine the validation values corresponding to a particular subset without knowledge of one or more of the validation segments in the particular subset; storing the set of validation segments with the file on the archive server; storing the recoverability attributes in an association with corresponding validation segments of the file, the recoverability attributes for subsequent comparison with the corresponding validation values; and receiving a challenge, the challenge indicative of a request to validate recoverability of the file from the archive server, further comprising: identifying, at the archive server, the validation function; determining, as a function of the received challenge, an indication of the subset of validation segments; applying the validation function to each of the validation segments in the indicated subset to compute a validation value; and comparing the validation value to a corresponding recoverability attribute to assess recoverability of the file.