Abstract: Audio jack coupled secure magnetic card readers in accordance with embodiments of the invention are described. One embodiment includes reading data from at least one track of data encoded on a magnetic stripe using a magnetic read head, encrypting the data using an encryption circuit, encoding the encrypted data into a transmission format using an encoder, passing the encoded data through an anti-aliasing filter to generate a data signal, and transmitting the data signal. on the microphone channel of an audio jack.

Abstract: A system for verifying the authenticity of data contained in a magnetic medium using the remanent noise characteristics of the magnetic medium. In one embodiment, the invention includes a sensing unit configured to generate a signal indicative of the magnetic field of the magnetic medium, an analog-to-digital converter (ADC) in communication with the sensing unit and configured to digitize the analog signal, a filter in communication with the ADC configured to enhance the component of the signal associated with the remanent noise characteristic, a data extraction unit, in communication with the ADC and the filter configured to measure at least bit duration and peak location and an authentication extraction unit, in communication with the filter and the data extraction unit configured to extract a set of scaled samples from the output of the filter representative of the remanent noise characteristic.