Secured SMS by Nokia: A_Brief_Introduction_to_Secure_SMS_Messaging_in_MIDP_en.pdf

The Legion of the Bouncy Castle
http://www.bouncycastle.org/

The idea is not how to secure SMS, because it is already done and available in the market, but how to make Secure SMS accessible to all or majority of users, whithout the need to modfy/interfere with their SIM card data and configuration. Basically we need the Secure SMS to be used in the most convenient way and covering a maximum of users.

A secure SMS API such as the Nokia example here under could be perfect,

The disadvantage is not the API itself but the fact that one need to install it on the mobile phone Sim menu, thus intervention is need on all users phones and that could be a gigantic task for a payment system that would like to address the masses

The Docomo Example:

NTT DoCoMo launched 'i-Mode', a WAP-based solution in Japan and it has been a huge success.
http://voicendata.ciol.com/content/goldbook/goldbook07/107031222.asp

The Felica system is based on the Sony smart-card technology of the same name. Smart cards are usually about the size of a credit card and contain a microchip inside that can be loaded with personal data.

All the handsets used with DoCoMo's new service run on the Symbian operating system, a company representative said on Monday.