Are there signature or transaction signing or bluetooth Gems?

Hello, I say hello to the Rails community. I have been away for 12 years. I regularly encounter websites that have that crisp Rails simplicity.

Around July of 2007 I worked through Rails Space Building a Social Network, and I have Agile Web Development. Both books with the front cover and table of contents chewed up by the Border Collie Chip who wanted me to take him to the beach. A really smart dog, may he rest in peace.

What I want to do is write an Affinity Group Paid Commute Ride Sharing application. The payment part is going to be done with a unit of exchange called NEFFC for Not Emit Fossil Fuel Co2. The payment activity and the ride matching I hope to do with a PC sending text messages back and forth to cell phones. The unit of exchange works about to about $40 per week per participant. The goal is for the participants to not buy $40 of gas per week, and for the extra trouble, they are paid about $40 in the NEFFC unit. The NEFFC can be exchanged for use of an electric commute car and construction of a solar array to charge the cars during the work day.

Please direct me to any Gems that do anything like the following activities:

I need a Gem to do Bluetooth cell phone connection from a PC to a cell phone. I need a Gem to attach a signature, date and checksum to a message. I need a Gem to attach a checksummed message to a transaction file somewhat like a block chain. I don’t quite understand the details of block chain.

Thanks for a few Gem names, Cordially yours, Lee