The fourth time I called, a human being answered the phone and told me the problem had been fixed. I hurried back to the A.T.M., scanned in my QR code, sent some Voldemorts $25 in crisp bills and called my mom. The whole experience had not done much to allay my misgivings about Bitcoin; what did allay them was Mike Hoats, the nice bearded man Coin Cafe sent over to fix the A.T.M.

We got to talking after I made my payment, and he told me that, while no one at Coin Cafe believed people should fund criminal activity by paying the ransom, their job was to broker the purchase and sale of Bitcoins, which, like cash, could be used for any purpose. CryptoWall had thrust them into the unwitting role of ransomware advisers, coping with grandmothers crying on the phone at the thought of losing all their photos or small-business owners whose family income was on the line. Coin Cafe didn’t like profiting from the victims (according to the company, these transactions are in the low single digits as a percentage of its total business), but they were downright mortified to learn that CryptoWall had anointed them as one of their Bitcoin providers of choice, with praise for their “fast, simple service.” That’s how my mom found out about Coin Cafe — from her ransom note.

This referral is only one of the handy services CryptoWall provides to ensure a more seamless customer experience. Others include the ability to “decrypt one file for free” and a message interface one can use “in case of any problems with payment or having any other questions.” What next, I wondered. Twenty percent off when you refer this malware to a friend? Frequent virus cards? Black Friday ransom specials?

“I THINK they like the idea they don’t have to pretend they’re not criminals,” Chester Wisniewski, a senior security adviser at the computer security firm Sophos, told me when I reached him in Vancouver by phone. “By using the fact that they’re criminals to scare you, it’s just a lot easier on them.” They don’t have to hire a professional translator to get their English perfect, Mr. Wisniewski explained, or engage in any of the baroque subterfuge required of someone pretending to be a Nigerian gentleman farmer who just needs a little help claiming his inheritance.

In addition to being criminals, these peddlers of ransomware are clearly businesspeople, skillfully appropriating all the tools of e-commerce. From branding (CryptoWall is a variant of a fearsome earlier virus called CryptoLocker, which was shut down last year) to determining what they can extort (ransomware hackers have tested the market with prices as low as $100 and as high as $800,000, which the city of Detroit refused to pay in order to have its database decrypted), these operators are, as Mr. Wisniewski put it, part of “a very mature, well-oiled capitalist machine.” It’s also an incredibly lucrative machine: Some experts estimate that CryptoLocker hackers cleared around $30 million in 100 days in 2013. And more than a million PCs worldwide have been hit with the CryptoWall virus.