Yup, it&#x27;s as simple as putting a magnetic stripe reader and putting it into a shell.  These are a commodity on Alibaba now [1].<p>The idea of using headphone jack for data transfer has been around since the Commodore PCs [2]<p>The software side is pretty standard too [3].  It&#x27;s a standard analog to digital conversion.<p>[1] <a href="http:&#x2F;&#x2F;www.alibaba.com&#x2F;showroom&#x2F;headphone-jack-magnetic-card-reader.html" rel="nofollow">http:&#x2F;&#x2F;www.alibaba.com&#x2F;showroom&#x2F;headphone-jack-magnetic-card...</a><p>[2] <a href="http:&#x2F;&#x2F;www.zimmers.net&#x2F;anonftp&#x2F;pub&#x2F;cbm&#x2F;crossplatform&#x2F;transfer&#x2F;transfer.html#wire-tape-audio" rel="nofollow">http:&#x2F;&#x2F;www.zimmers.net&#x2F;anonftp&#x2F;pub&#x2F;cbm&#x2F;crossplatform&#x2F;transfe...</a>
And 
<a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Commodore_Datasette" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Commodore_Datasette</a><p>[3] <a href="http:&#x2F;&#x2F;www.slideshare.net&#x2F;ShipengXu&#x2F;data-transmission-through-audio-jack-on-ios" rel="nofollow">http:&#x2F;&#x2F;www.slideshare.net&#x2F;ShipengXu&#x2F;data-transmission-throug...</a>