  Akbarpour and Li (2020) formalized credibility as an auction desideratum
where the auctioneer cannot benefit by implementing undetectable deviations
from the promised auction and showed that, in the plain model, the ascending
price auction with reserves is the only credible, strategyproof,
revenue-optimal auction. Ferreira and Weinberg (2020) proposed the Deferred
Revelation Auction (DRA) as a communication efficient auction that avoids the
uniqueness results from Akbarpour and Li (2020) assuming the existence of
cryptographic commitments and as long as bidder valuations are MHR. They also
showed DRA is not credible in settings where bidder valuations are
$\alpha$-strongly regular unless $\alpha > 1$. In this paper, we ask if
blockchains allow us to design a larger class of credible auctions. We answer
this question positively, by showing that DRA is credible even for
$\alpha$-strongly regular distributions for all $\alpha > 0$ if implemented
over a secure and censorship-resistant blockchain. We argue ledgers provide two
properties that limit deviations from a self-interested auctioneer. First, the
existence of smart contracts allows one to extend the concept of credibility to
settings where the auctioneer does not have a reputation -- one of the main
limitations for the definition of credibility from Akbarpour and Li (2020).
Second, blockchains allow us to implement mechanisms over a public broadcast
channel, removing the adaptive undetectable deviations driving the negative
results of Ferreira and Weinberg (2020).
