A method of identifying anomalous behavior can include transforming input data to a series of numbers, determining first features and second features of the series of numbers that, given the same numbers in a different order, produce a different value for the respective feature, encoding the series of numbers by a key value indicating a number associated with a cell of a grid of cells to which the first and second features map, and determining, based on whether the key value has been previously provided, whether the input is anomalous.