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Broadcast authentication mechanisms are essential to cyber-physical systems that communicate through wireless links such as wireless sensor networks (WSN) and body area network (BAN). Even though symmetric key-based authentication schemes are more prevalent among these systems, public key-based digital signature schemes have started to gain ground; notably, several research efforts have been focused on the Elliptic Curve Cryptosystem due to its low overheads. As a combination of sensing and computing platform, WSN must handle both time-sensitive as well as delay-tolerant but security-sensitive data. The cryptographic strength and verification delay of an elliptic curve digital signature are determined by the parameters of the curve's underlying finite held. The held's parameters and public key are usually generated and distributed before the WSN's deployment thus cannot be changed easily. This situation creates a need for a multi-resolution digital signature scheme that provides the signer a choice to trade off a signature's strength for faster verification time and less power consumption. In this paper, we present a digital signature scheme called Multi-Resolution Elliptic Curve Signature (MRECS) that allows the signer the ability to create signatures of different strengths from the same public key set. Compared to an implementation using a set of different keys, MRECS requires less storage overhead and has longer key lifetime at the cost of slightly higher but acceptable communication overhead. MRECS yields up to 33% computational overhead reduction compared to that of the full-size signature while maintaining a full elliptic curve strength regardless of a signature strength.