2009
Michael Paik and Lakshminarayanan Subramanian
ACM SIGOPS Operating Systems Review

SigNet: Low Cost Auditable Transactions using SIM cards and Mobile Phones
The absence of reliable network connectivity in the developing world has resulted in the use of paper receipts remaining the de facto standard for tracking transactions of various types. This includes both cash transactions (microfinance-related disbursements and repayments, purchases, money transfers) and noncash goods (food commodities to/from godowns or warehouses). Such receipts are susceptible to loss, damage and alteration . . .