Proof of retrievability for archived files

摘要

A proof of retrievability (POR) mechanism is applicable to a data object for providing assurances of data object possession to a requesting client by transmitting only a portion of the entire data object. The client compares or examines validation values returned from predetermined validation segments of the data object with previously computed validation attributes for assessing the existence of the data object. Since the archive server does not have access to the validation function prior to the request, or challenge, from the client, the archive server cannot anticipate the validation values expected from the validation function. Further, since the validation segments from which the validation attributes, and hence the validation values were derived, are also unknown to the server, the server cannot anticipate which portions of the data object will be employed for validation.

主权项

1. A method comprising:
identifying a set of validation portions from a plurality of data portions comprising a data object, the set of validation portions including one or more subsets of validation portions for verifying recoverability of the data object; determining, for each of the one or more subsets of the set of validation portions, recoverability attributes applicable to the subset of the set of validation portions; defining a validation function, the validation function responsive to a challenge and for computing validation values, the validation values for comparison with corresponding recoverability attributes based on a particular subset of the set of validation portions from which the recoverability attributes were derived, the recoverability attributes for subsequent comparison with the corresponding validation values; receiving a challenge indicative of a request to validate recoverability of the data object; identifying the validation function responsive to the challenge for computing validation values; determining, as a function of the received challenge, an indication of the subset of validation portions; applying the validation function to each of the validation portions in the indicated subset to compute a validation value; and comparing the validation value to a corresponding recoverability attribute to assess recoverability of the data object.