In 2013, candidate Bill de Blasio promised a more transparent and open City Hall. This week, Mayor de Blasio claimed his administration has “a lot of transparency.”

He has a funny way of showing it.

De Blasio’s administration has denied an open-records request for emails between city officials and political consultant Jonathan Rosen, a trusted de Blasio adviser. The mayor’s dealings with Rosen — whose firm, BerlinRosen, has close ties to de Blasio, his 2013 mayoral campaign, and his nonprofit lobbying group, the Campaign for One New York — have come under scrutiny. BerlinRosen received subpoenas related to federal and state investigations into the mayor’s fundraising.

De Blasio has denied wrongdoing and has promised to back up his assertions. He has said the Campaign for One New York’s activities were separate from City Hall’s — and yet now, by fighting requests for records, he’s tying the two together with claims for a need for privacy. He can’t have it both ways.

In explaining the denial of records, de Blasio cited a little-known exception to the state’s Freedom of Information Law. Rosen, de Blasio said, is an “agent of the city.”

Not so fast, says Robert Freeman, the executive director for the state’s Committee on Open Government. It is true that correspondence that includes opinions and recommendations can be kept private when it’s between city officials and consultants retained by the government. But Rosen isn’t paid by New York City — so his correspondence in this case should be public record, Freeman said.

The mayor’s counsel, Maya Wiley, said she thinks personal advisers can fit that exception, and she’s named five, including Rosen, who she says do. We have our doubts — and the Freedom of Information Law operates under a presumption of access. A blanket “no” is unacceptable. Any correspondence regarding facts, statistics or data, for instance, is public, even if Rosen were a city “agent.”

Perhaps de Blasio wants his own version of transparency and access. It doesn’t work that way. He has promised openness — but he’s making those promises from behind a closed door and an opaque curtain.