Patent ID: 7822666

Claim:
A computer-implemented method, comprising: distributing a transaction number generator to a first user; generating, at the transaction number generator, a plurality of single-use transaction numbers including a first single-use transaction number, wherein each single-use transaction number includes a routing number, an account number, and a one-time password, wherein the routing number and account number remain constant for each single-use transaction number in the plurality of single-use transaction numbers, wherein generating includes generating each one\-time password in the transaction number generator distributed to the first user so such that it is difficult to predict subsequent one-time passwords; and paying for a transaction, wherein paying includes transmitting the first single-use transaction number generated by the transaction number generator from the transaction number generator over a network to a transaction number validator: and validating, at the transaction number validator, the first single-use transaction number, wherein validating includes receiving the first single-use transaction number transmitted from the transaction number generator via the network, generating in the transaction number validator an expected one-time password and comparing the one-time password of the received first single-use transaction number with the expected one-time password, wherein the expected one-time password reflects the one-time password expected by the transaction number validator to be part of the first single-use transaction number; wherein each single-use transaction number is formatted at the transaction number generator such that its respective routing number can be used to route the single-use transaction number to the transaction number validator and wherein generating the one-time password in the transaction number generator distributed to the first user includes receiving at the transaction number generator a first personal identification number (PIN) and slowing down generation of the one-time password if the first personal identification number received is different than expected.