Secure email itself is hardly a new idea, and the 'old-school' way of implementing it relies on pubic key cryptography. As recent events have reconfirmed, introducing an intermediary is not a very good idea if communication between two parties is to be and remain secure. They are trying to make it 'easy' for users by taking care of key management and shifting all cryptographic operations to the server. There have been quite a few new services that are trying to reinvent secure email in recent years. The underlying RF standard used varies by manufacturer, and both Type A and Type B are common. While smart cards that have only a contactless interface do exist, dual-interface cards that have both contacts and an antenna for RF communication are the majority. The communication protocol (T=CL) they use is defined in ISO 14443 and is very similar to the T1 protocol used by contact cards. They draw power and communicate with the reader using RF induction. Contactless cards on the other hand do not need to have physical contact with the reader. Those traditional cards are referred to as ' contact smart cards'.

Size, electrical characteristics and communication protocols are defined in the 7816 series of ISO standards.

The pads are used to both provide power to the card and establish serial communication with its I/O interface. Traditionally, smart cards connect with a card reader using a number of gold-plated contact pads. As discussed in previous posts, a smart card is a secure execution environment on a single chip, typically packaged in a credit-card sized plastic package or the smaller 2FF/3FF/4FF form factors when used as a SIM card.

Android nfc smart card reader