Performance and Security Evaluation of 256-bit Elliptic Curves for Resource-Constrained UVS Systems: A Comparative Study of Curve25519, Edwards25519, secp256r1, and secp256k1

Unmanned Vehicle Systems (UVS) require secure and efficient cryptographic mechanisms to protect communication links from interception and unauthorized control. However, these systems often rely on resource-constrained embedded hardware with limited processing power, memory, and energy. Elliptic Curve Cryptography (ECC) is therefore a suitable candidate because it provides strong security with relatively small key sizes. This study evaluates the performance and security of four standardized 256-bit elliptic curves: Curve25519, Edwards25519, secp256r1, and secp256k1. The comparison focuses on Elliptic Curve Point Multiplication (ECPM), the most computationally expensive operation in ECC-based key exchange and digital signature protocols. To ensure fairness, all curves were evaluated using the same 256-bit scalar, constant-time Montgomery ladder scalar multiplication, and projective coordinates to avoid costly modular inversions. The methodology combines a mathematical analysis based on an assumed 8-bit microcontroller model with software-based Python experiments on a general-purpose platform. The experiments compare the relative behavior of the curves under identical conditions, while the implications for constrained devices are interpreted through their mathematical structure and implementation characteristics. The mathematical and experimental comparison shows that Edwards25519 and Curve25519 achieve higher computational efficiency and lower memory usage than secp256r1 and secp256k1, while maintaining approximately 128-bit classical security. They also provide stronger implementation-level security due to their efficient curve forms, regular arithmetic structures, and resistance to side-channel-related implementation risks. In contrast, secp256r1 and secp256k1 require more execution time, memory, and implementation care. Overall, Curve25519 and Edwards25519 are the suitable candidates for secure cryptographic deployment in resource-constrained UVS systems, especially highly constrained microcontroller-based platforms such as 8-bit devices.