Security experts informs that Google Wallet stores unencrypted data on mobile devices. Informations such as cardholder name, transactions dates, last four digits of credit card number, account alance are not encrypted. ViaForensics informs that the application encrypts only credit card number.
„While Google Wallet does a decent job securing your full credit cards numbers (it is not insecurely stored and a PIN is needed to access the cards to authorize payments), the amount of data that Google Wallet stores unencrypted on the device is significant (pretty much everything except the first 12 digits of your credit card). Many consumers would not find it acceptable if people knew their credit card balance or limits“ - the company states.

Source: The Register
15.12.2011