In this paper, we propose a new cryptosystem based on matrix translation and Elliptic curve cryptography for developing a secure routing algorithm to provide energy efficient and secured data communications in Wireless Sensor Networks. Moreover, the newly proposed techniques are implemented by decomposing the process into the key generation phase, encryption phase, cluster based secure routing phase and decryption phase. For this purpose, we introduce two new tables namely space reference table and String Position based ASCII value and Prime number generation Table. Here, the Space reference table is used to assign the values for the spaces that are occurring in the sentence before the encryption and decryption process. Next, it uses the String Position based ASCII value and Prime number generation Table developed in this work to convert the strings into numerical digits and to allocate the nearest prime number for the generated numerical digits. In addition, we propose two new algorithms namely ASCII AND PRIME NUMBER based Encryption/Decryption Algorithm and a Secure Routing Algorithm using cipher text conversion and distance vectors called Matrix Translation and Elliptic Curve based Cryptosystem for Secure Routing Algorithm for performing cluster based and energy efficient secure routing. The major advantages of the proposed secure routing system include the increase in security, packet delivery ratio and overall network performance and also decrease in energy consumption and delay. This work has been implemented using NS2 simulator and Java. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.