Auction is a promising approach for dynamic spectrum access in Cognitive Radio Networks. Existing auction mechanisms are mainly proposed to be strategy-proof to stimulate bidders to reveal their valuations of spectrum truthfully. However, they would suffer significantly from a new cheating pattern named false-name bids, where a bidder can manipulate the auction by submitting bids under multiple fictitious names. We show such false-name bid cheating is easy to make but hard to be detected in dynamic spectrum auctions. To resolve this issue, we propose ALETHEIA, a novel flexible, false-name-proof auction framework for large-scale dynamic spectrum access. ALETHEIA has the following important features: (1) it not only guarantees strategy-proofness but also resists false-name bids, (2) it enables spectrum reuse across a large number of bidders, (3) it provides the bidders the flexibility of diverse demand formats, and (4) it incurs low computational overhead. Simulation results show that ALETHEIA achieves both high spectrum redistribution efficiency and auction efficiency.