Patent ID: 8183980
Filing Date: 2012-05-22
Classification: G07C,H04L

Abstract:
1. A method of maintaining a secure access system that uses a unidirectional communication protocol, the secure access system comprising at least one credential, at least one reader, and a device upstream of said reader, the method comprising: reading a credential with a reader; said reader generating a first message comprising credential data associated with said credential and a first code; transmitting said first message to an upstream device; said upstream device analyzing said credential data in order to determine the authenticity of said credential and further analyzing said first code in order to determine the authenticity of said reader; receiving, at said reader, a prompting signal transmitted by said upstream device; in response to receiving said prompting signal from said upstream device, said reader generating a second message comprising a second code, wherein said second code is different from said first code; and transmitting, by said reader, said second message to said upstream device, wherein a first code selection algorithm is used to generate said first code, wherein said first code selection algorithm generates said first code based upon at least one of time of day, total operation time of said reader, a reader unique ID, number of cards read, and a reader manufacturer ID, wherein a second code selection algorithm is used to generate said second code, and wherein the first and second code selection algorithms are different.