Wireless Transport Layer Security (WTLS) is a security protocol, part of the Wireless Application Protocol (WAP) stack. It sits between the WTP and WDP layers in the WAP communications stack.
WTLS is derived from TLS. WTLS uses similar semantics adapted for a low bandwidth mobile device. The main changes are:
- Compressed data structures — Where possible packet sizes are reduced by using bit-fields, discarding redundancy and truncating some cryptographic elements.
- New certificate format — WTLS defines a compressed certificate format. This broadly follows the X.509 v3 certificate structure, but uses smaller data structures.
- Packet based design — TLS is designed for use over a data stream. WTLS adapts that design to be more appropriate on a packet based network. A significant amount of the design is based on a requirement that it be possible to use a packet network such as SMS as a data transport.
WTLS has been superseded in the WAP Wireless Application Protocol 2.0 standard by the End-to-end Transport Layer Security Specification.