topic Re: Longitudinal Redundancy Check (LRC) Process in Integration and Testing

Longitudinal Redundancy Check (LRC) Process

swainjk — Fri, 23 Mar 2012 15:11:09 GMT

The Card-Present Transactions Implementation Guide, Appendix E, requires a longitudinal redundancy check (LRC) prior to submitting the track data. It specifies that the LRC character follows the End Sentinel. It does not specify how the LRC is calculated. I have a 2-part question:

1) Every card that I have checkrf has a semi-colon (":")in the position and using Telecom standard ISO 1155 for LRC calculation does not produce a byte value that converts to a semi-colon. My question is what characters are included in the LRC calculation (at which characters does the calculation start and stop and is the semi-colon really the LRC value?

2) The guide does not provide instructions on how to submit the LRC calculation result to Authorize.Net. How do you really know if I did it or not? Is it really necessary?

Re: Longitudinal Redundancy Check (LRC) Process

TJPride — Fri, 23 Mar 2012 20:36:27 GMT

That's an operation specific to the swiper, as in the swiper should be doing the check and throwing an error if the calculation is off. What you get out of the swiper should be text that's able to be fed straight into Authorize.net. Does your swiper not do the conversions?

Re: Longitudinal Redundancy Check (LRC) Process

swainjk — Wed, 28 Mar 2012 17:04:06 GMT

Thanks for clarifying. The guide did not do a good job here.