Patent ID: 8311218

Claim:
Logic encoded in one or more non-transitory tangible media for execution with a processor and when executed, is operable to: generate, from a first value, based on rounding information, a first security key that matches a second security key whenever the first value and a second value from which the second security key is generated differ by less than a non-zero predetermined amount; wherein the second security key is generated from the second value rounded to a multiple of a rounding interval nearest to the second value; and wherein the rounding information includes a rounding direction indication, the rounding direction indication indicative of a direction in which the second value is rounded to the multiple of the rounding interval nearest to the second value, wherein the logic operable to generate the first security key is further operable to: when the first value minus a floor value is less than one-fourth of the rounding interval or greater than three-fourths of the rounding interval, round the first value to a multiple of the rounding interval nearest to the first value, the floor value being a multiple of the rounding interval nearest to and less than or equal to the first value; and when the first value minus the floor value is between one-fourth of the rounding interval and three-fourths of the rounding interval, round the first value to a multiple of the rounding interval nearest to the first value in the direction determined from the rounding direction indication.