This document defines the crypto suite for SPECK for the ISO/IEC 18000 air interfaces standards for radio frequency identification (RFID) devices. Its purpose is to provide a common crypto suite for security for RFID devices that can be referred to by ISO committees for air interface standards and application standards. The crypto suite is defined in alignment with existing air interfaces. SPECK is a symmetric block cipher that is parameterized in both its block length and key length. In this document, a variety of block/key length options are supported. This document defines various methods of use for the cipher. A Tag and an Interrogator can support one, a subset, or all of the specified options, clearly stating what is supported.