A method and system to verify a transaction are described. The system may
include a token generator to issue a client set of tokens to a client, a
token verification list generator to issue a verification set of tokens
to a provider, a communication module to receive a request from the
provider to redeem a provider set of tokens, and a redemption module. The
redemption module may be configured to compare the provider set of tokens
with the client set of tokens and to selectively redeem the provider set
of tokens based on the results of the comparison.