Abstract: A method of verifying an unverified token received may include accessing an external data store to receive data vectors that may be associated with a user of the client device; filtering data vectors that are not input data vectors; grouping data vectors into first groups based on a text field in each of the data vectors; selecting second groups from the first groups where each of the second groups include data vectors with a similar value field; selecting third groups from the second groups where each of the third groups includes data vectors with a similar input interval; for each of the third groups, determining a group value based on the value fields and input intervals; calculating an estimated token based on the group values for each of the third groups; and determining whether the unverified token can be verified by the estimated token.