Eliot Shore, a widower who lives in Ottawa, is suing Avid Dating Life Inc and Avid Life Media Inc, the corporations that run Ashley Madison.com, law firms, Charney Lawyers and Sutts, and Strosberg said in a statement.
He joined the website "for a short time in search of companionship," but never met anybody in person, they said in a statement.
Since the hack last month, Avid Life has indefinitely postponed the adultery site's IPO plans. Avid values itself at $1 billion and reported revenue of $115 million in 2014, up 45 percent from the preceding year.
The hackers object to the site's business practices, specifically a "paid delete" option that allows people to pay to remove all their information but, they say, does not actually do that.
David Kennedy, founder and security consultant at TrustedSec, said that the fresh release appears to be authentic.
"Everything appears to be legit," he said in an email. "We have portions downloaded and its confirmed legitimate thus far."
A report in Vice Media's online technology site Motherboard, which first reported the new data dump, said the release bore the same fingerprints as Tuesday's release.
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The additional release will likely ratchet up the pressure on Avid Life, which has been quiet about exactly how much and what sort of data was stolen in a breach in July.
The company, which also owns websites CougarLife.com and EstablishedMen.com, did not immediately respond to requests for comment.