Wireless reprogramming in a wireless sensor network (WSN) involves the process of propagating a new code image or relevant command to sensor nodes. As a WSN is usually deployed in a hostile environment, secure reprogramming is a major concern. Recently, He et al. proposed a secure distributed reprogramming protocol, SDRP, based on an identity-based signature (IBS) scheme. Subsequently, they showed that SDRP is insecure against impersonation attacks due to the use of insecure IBS scheme. They then proposed a modified SDRP (MSDRP) based on Barreto et al.’s IBS scheme which is provably secure under a mathematically hard problem. Also, they proposed a DoS-resistant distributed code dissemination protocol, DiCode, based on a warrant-based proxy signature scheme. However, the two protocols are inefficient on sensor nodes: MSDRP requires a heavy pairing computation and DiCode requires two modular exponentiations with an RSA modulus n whose size is 1024 bits at an 80-bit security level to verify a signature. In this paper, we show that MSDRP with the implementation of eta T paring defined on E(F_{3^97} x E(F_{3^97}) ->E(F_3^{697}) is entirely broken. We then propose a new SDRP, S2DRP, based on a pairing-free IBS scheme to reduce the computational and communication overhead and give its performance results.