Resource constrained encryption does not have an extensive history in symmetric cryptography. Examples of recent lightweight block ciphers are HIGHT and PRESENT. However, both of them do not afford favorable security against attacks such as linear and differential cryptanalysis. Portable handheld devices in wireless communication systems are rising as strong competitors to large traditional electronic devices and require advanced safety and security mechanisms. Scalable Encryption Algorithm (SEA) is one such security mechanism specially designed for wireless applications with portable devices like sensor nodes, RFIDs and other low power operated electronic gadgets. This paper describes SEA, a block cipher that provides lightweight security solution that conquers the limitations of resource constrained environments.