Dennis Shasha

Secure Rural Banking On	a Single Insecure Cellphone

AUTHORS: Dennis Shasha

Providing basic financial services to rural people can enhance their
security by eliminating the need for them to hold cash
and can offer them alternative venues for borrowing.
Placing a branch in rural villages is not however cost effective.
In recent
years, the concept of branchless banking has emerged in which a person
who has a phone and sufficient liquidity (called a shopkeeper hereafter)
acts as a bank agent.
Others in the village (hereafter called farmers) perform withdrawals
and depositions with the shopkeeper.
Because the farmers and shopkeepers may not trust one another completely,
though they both trust the bank.
Because the possibilities for fraud are legion, some form of security is
The farmers are unsophisticated, so the protocols
must be simple and intuitive.
We present such a protocol that is robust to dishonest shopkeepers, farmers,
and eavesdroppers. The protocol assumes that at least the shopkeeper has a
phone and that the farmer can read numbers
and can converse.