1. Experimenting with Electronic Commerce on the PalmPilot
Neil Daswani, Dan Boneh,
Stanford University

2. Trade-offs Vs. SmartCards no tamper resistance
no cryptographic accelerators
direct line of communication with user
more processing power
more memory

3. Trade-offs
Vs. Desktops
less memory
less processing power
portable

4. Cryptographic Primitives
* DES, SHA-1, RSA figures obtained with SSLeay
* ECC-DSA figures obtained with Certicom Security Builder Toolkit

5. E-Commerce on a PDA Small payments ($5 -> $50)
Target Application: Pony Vending Machine
Pre-pay
Vendor-specific
Where to start?
PayWord (Rivest, Shamir)

6. PDA-PayWord PalmPilot implementation of PayWord
Minimize cryptographic operations
Minimize storage requirements

7. PDA-PayWord: WithdrawalYk
{Yk, k, d, vid}SECC-DSA(User)
User’s
Wallet
Bank
Pre-Paid?
Yes
HCC=
{Yk, k, d, exp,vid}SRSA (Bank)

8. PDA-PayWord: PurchaseYk
User’s
Wallet
Yk-i+1
Yk-i
Yk-i, i, HCC
Yk-i Y1
Vendor Y0

9. PDA-PayWord: Withdrawal Timings
Note: d = 5

10. PDA-PayWord: Purchase Timings
(First time $1.50 buy)

11. Conclusions / Summary
PDA = portable commerce device w/o tamper resistance
Suitable for small payments
Commerce protocols can be adapted
Example: PDA-PayWord
leverages best of ECC and RSA
Acknowledgements: Andrew Toy
& Certicom