Implementing RSA in smart cities

Privacy-preserving Smart City“Implementing RSA for sensor nodes in smart cities” was published as part of the “Special issue on security and privacy for smart cities” by the “Personal and Ubiquitous Computing” peer-reviewed journal.

Article abstract: In smart city construction, wireless sensor networks (WSNs) are normally deployed to collect and transmit real-time data. The nodes of the WSN are embedded facility that integrated sensors and data processing modules. For security and privacy concerns, cryptography methods are required for data protection. However, the Rivest-Shamir-Adleman (RSA) cryptosystem, known as the the most popular and deployed public key algorithm, is still hardly implemented on embedded devices because of the intense computation required from its inherent arithmetic operations. Even though, different methods have being proposed for more efficient RSA implementations such as utilizing the Chinese remainder theorem, various modular exponentiation methods, and optimized modular arithmetic methods. In this paper, we propose an efficient multiplication for long integers on the sensor nodes equipped with 16-bit microcontrollers. Combined with this efficient multiplication, we obtain a faster Montgomery multiplication. The combined optimized Montgomery multiplication, the Chinese remainder theorem, and the m-ary exponentiation method allowed for execution times of less than 44.6 × 106 clock cycles for RSA decryption, a new speed record for the RSA implementation on MSP430 microcontrollers.