A computer-implemented method of electronically authenticating a user at a venue or event entry, comprising: electronically storing in a database, per user, an account comprising a unique user identifier, a unique identifier of a mobile device of the user, and ticket data for at least one ticket purchased by the user; executing a code generation program on a certain mobile device of a user such that the certain mobile device locally and periodically creates and displays a bar code unique to the mobile device user and the certain mobile device, the locally, periodically created bar code comprising a user identifier candidate value, a mobile device identifier candidate value, and a date/time candidate value, the bar code being independent of venue and event data; and at a venue or event entry subsystem, with the certain mobile device displaying the locally and periodically created bar code: a) electronically reading the bar code from the certain mobile device, b) electronically decoding the bar code into the user identifier candidate value, the mobile device identifier candidate value, and the date/time candidate value, and c) electronically accessing a unique user identifier stored in the database using the decoded mobile device identifier candidate value, and comparing a first one-way encryption hash of the user identifier candidate value, the mobile device identifier candidate value, and date/time candidate value with a second one-way encryption hash of the unique user identifier and the unique mobile device identifier accessed from the database and of a date/time value, wherein when the comparing results in a match of the first one-way encryption hash and the second one-way encryption hash, automatically positively authenticating the mobile device user at the venue or event entry, and, determining if there are tickets for the event associated with the account of the user; in response to determining that there are tickets for the event or venue associated with the account of the user, allowing or enabling the user to redeem the tickets for the event or venue associated with the account of the user to gain entry to the event or venue; and wherein the code generation program is configured with the unique user identifier and the unique mobile device identifier prior to execution on the certain mobile device. electronically storing in a database, per user, an account comprising a unique user identifier, a unique identifier of a mobile device of the user, and ticket data for at least one ticket purchased by the user; executing a code generation program on a certain mobile device of a user such that the certain mobile device locally and periodically creates and displays a bar code unique to the mobile device user and the certain mobile device, the locally, periodically created bar code comprising a user identifier candidate value, a mobile device identifier candidate value, and a date/time candidate value, the bar code being independent of venue and event data; and at a venue or event entry subsystem, with the certain mobile device displaying the locally and periodically created bar code: a) electronically reading the bar code from the certain mobile device, b) electronically decoding the bar code into the user identifier candidate value, the mobile device identifier candidate value, and the date/time candidate value, and c) electronically accessing a unique user identifier stored in the database using the decoded mobile device identifier candidate value, and comparing a first one-way encryption hash of the user identifier candidate value, the mobile device identifier candidate value, and date/time candidate value with a second one-way encryption hash of the unique user identifier and the unique mobile device identifier accessed from the database and of a date/time value, a) electronically reading the bar code from the certain mobile device, b) electronically decoding the bar code into the user identifier candidate value, the mobile device identifier candidate value, and the date/time candidate value, and c) electronically accessing a unique user identifier stored in the database using the decoded mobile device identifier candidate value, and comparing a first one-way encryption hash of the user identifier candidate value, the mobile device identifier candidate value, and date/time candidate value with a second one-way encryption hash of the unique user identifier and the unique mobile device identifier accessed from the database and of a date/time value, wherein when the comparing results in a match of the first one-way encryption hash and the second one-way encryption hash, automatically positively authenticating the mobile device user at the venue or event entry, and, determining if there are tickets for the event associated with the account of the user; in response to determining that there are tickets for the event or venue associated with the account of the user, allowing or enabling the user to redeem the tickets for the event or venue associated with the account of the user to gain entry to the event or venue; and wherein the code generation program is configured with the unique user identifier and the unique mobile device identifier prior to execution on the certain mobile device.