Systems and methods consistent with the present invention encode a list so users of the list may make inquires to the coded list without the entire content of the list being revealed to the users. Each item in the list turns on one or more bits in the array 110. Once each item in the list has been encoded by an encoder, a bit array with high and low values is used to represent the items in the list. The bit array may be embodied in a validation system for allowing users to query the list to determine whether an inquiry item is on the list 105. The validation system determines which bits to check by executing the same coding process executed by the encoder. If all the bits are high, then the inquiry item is determined to be part of the list, if at least one of the bits is low, then the inquiry item is determined not to be part of the original list. An exemplary encoder and validation system comprises a standardizer, a hashing function unit, an extraction circuit, and an offset circuit.