It is claiming to be an approach to avoid censorship though still unclear if it is secure for use. Many apps that work over mobile are to be highly insecure.
T Dev D of Samourai Wallet explains:
“Pony Direct can uses to forward bitcoin transactions via SMS even when internet connections are block or shut down. Simply using the app to send a transaction via SMS to any cooperating and internet-connected Android device. It will effectively route around any internet censorship being practices where the sender is live”.
The team bills itself as privacy activists and people who dedicate their lives to creating the software that Silicon Valley will never build. Thus the regulators will never allow and the VC’s will never invest in.
Internet censorship is a government favorite to shut down dissidents. However, there are many reason to believe it would be a first response when Bitcoin is a real threat. At present, SMS is the best way around to such scenarios.
T Dev D clarifies on the question of how SMS within the Samourai wallet operates:
“The issue is that as SMS can only contain up to 160 characters, a way to find to send as many SMS as possible. Thus to communicate the bitcoin transaction to the party capable of broadcasting it on the network. The first SMS in the sequence contains info on the total number of SMS in the series, the hash ID that must be matching at the end, a batch ID, a sequencing number, and a portion of the actual transaction hex. The following SMS contain a sequencing number, the batch ID, and more transaction hex data. Once the receiving device has accepted the expected number of SMS for a same batch from the same incoming number. The transaction data is extractes from each message and the entire transaction is re-assembles and pushing out to the bitcoin network”.
T Dev D explains the overall status of the project,
“Samourai is moving ahead with its roadmap and experiencing rapid growth during this period of mass media attention on the crypto-currency space”. Though the wallet is on Android at the moment, “We plan to have an iOS version of our wallet for later this year.”
The pony app is available on Github and built in-house as a proof-of-concept to invite other developers to participate in building tools for it.
Pavol Rusnak published an experimental project called Smspushtx last year to allow sending Bitcoin with SMS. He registered with an inbound SMS service provider Nexmo because they didn’t charge.
He used a virtual number that allows him a webhook and points at his Flask server. The server consumes and forwards messages. However, it limited messages to 160 characters. The messages are interlink together in a chain or series. The transaction is then pushes using an Insight service API.