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.