Hardware Watermarking is one of the popular countermeasures to prevent hardware counterfeiting. A robust watermark has to be invisible to the attacker, yet allow the verifier to access it easily. It should also be resistant to design transformations and should allow the defender to deploy at any stage in the design transformation process. To address this we propose SIGNED: A lightweight watermarking technique that relies on challenge-response generation. We evaluate SIGNED on ISCAS85, ITC99, and MIT-CEP benchmarks to show that SIGNED incurs less overheads and is resistant against removal and detection attacks.