IP protection is a recent field of research. If passive protection schemes, mainly IP watermarking and fingerprinting, have been studied for more than fifteen years, active protection schemes using remote activation/unlocking/metering of IPs are highlighted by several recent works. Like any other new field of research, new concepts appear with sometimes not such good ideas. IP unlocking scheme without cryptography, as recently proposed in this journal, is one of these ideas. Expecting to obtain low overhead and high security this way is very hard. This comment proves this by presenting a short yet deep study.