Digital fingerprinting was introduced for the protection of intellectual property (IP). Since each copy of the IP will receive a distinct fingerprint, it can also be used as an identification for the IP or the chip. However, existing fingerprinting techniques are not practical due to expensive cost of creating fingerprints and lack of effective methods to verify the fingerprints. In the paper, we propose a practical scan chain based fingerprinting method, where we utilize the Q-SD and Q'-SD connection styles in scan design to create digital fingerprint. This has two major advantages. First, fingerprints are created as a post-silicon procedure and therefore there will be little fabrication overhead; Second, altering the Q-SD or Q'-SD connection style requires us to modify test vectors in order to maintain fault coverage. This indeed enables us to verify the fingerprint from test vectors. We perform experiment on standard benchmarks to demonstrate the low design overhead of this approach. We also conduct security analysis to show that such fingerprints are robust against various attacks.