A key challenge of the embedded era is to ensure trust in reuse of intellectual properties (IPs), which facilitates reduction of design cost and meeting of stringent marketing deadlines. Determining source of the IPs or their authenticity is a key metric to facilitate safe reuse of IPs. Though physical unclonable functions solves this problem for application specific integrated circuit (ASIC) IPs, authentication strategies for reconfigurable IPs (RIPs) or IPs of reconfigurable hardware platforms like field programmable gate arrays (FPGAs) are still in their infancy. Existing authentication techniques for RIPs that relies on verification of proof of authentication (PoA) mark embedded in the RIP by the RIP producers, leak useful clues about the PoA mark. This results in replication and implantation of the PoA mark in fake RIPs. This not only causes loss to authorized second hand RIP users, but also poses risk to the reputation of the RIP producers. We propose a zero knowledge authentication strategy for safe reusing of RIPs. The PoA of an RIP producer is kept secret and verification is carried out based on traversal times from the initial point to several intermediate points of the embedded PoA when the RIPs configure an FPGA. Such delays are user specific and cannot be replicated as these depend on intrinsic properties of the base semiconductor material of the FPGA, which is unique and never same as that of another FPGA. Experimental results validate our proposed mechanism. High strength even for low overhead ISCAS benchmarks, considered as PoA for experimentation depict the prospects of our proposed methodology. © 2019 IEEE.