Security is a key aspect in networks that circulate critical information. Vehicular Ad Hoc Network (VANET) is one such network where vehicles transmit and receive traffic information and emergency alerts. It is imperative to ensure only legitimate nodes join the network, since VANET thrives on authentic and accurate information. This paper proposes a vehicle authentication scheme based on weak encryption. Weak encryption in this context means encryption is not used as a means to realize confidentiality but to achieve a less obvious goal of authentication. We present the scheme in a detailed manner, followed by a brief discussion. Our future work includes simulation studies to estimate overheads and exploring possibilities of integrating our scheme with others.