It’s a seller’s market for domains suggestive of Bitcoin, cryptocurrencies, and blockchains. The domain name Tokens.com sold for $500,000 in February. Cryptoworld.com sold for $195,000 in January. Eth.com sold for $2 million at the end of 2017. Blockchain.us wants $3.45 million, and Ethereum.com is asking for $10 million. In this climate, a domain like Crypto.com is likely worth millions of dollars. But Matt Blaze, who has owned it since 1993, isn’t selling.

“No, my domain name isn’t for sale. Yes, I mean it. Yes, I’ve probably already muted you,” he tweeted in September.

Blaze is an associate professor at the University of Pennsylvania and a well-regarded cryptography researcher who is credited with the phrase and concept of “trust management,” an important framework for modeling the authenticity and reliability of parties in information security. More recently, he has been heavily involved in cybersecurity research around voting machines, and he testified in front of Congress in November. He did not respond to a request for comment, but he apparently registered the domain fairly easily. “People my age could just register names like that when we were your age,” he told security researcher Melissa Elliott on Twitter.

“It’s actually an unbelievable domain,” said Niko Younts, who sold BitcoinWallet.com for $250,000 back in 2014 and currently holds a portfolio of more than 1,000 cryptocurrency-related domains. “That word ‘crypto’ is very powerful to industry leaders, and from a marketing perspective. It could be quite literally a $10 million domain.”

Other domain sellers agreed. The pseudonymous administrator of Crypto Domains, who claims to have sold coingeek.com to billionaire and cryptocurrency enthusiast Calvin Ayre, says they would price it “in the $5 to $10 million dollar range.” New.life, another domain seller who also asked to remain pseudonymous, also priced crypto.com at $5 million to $10 million. “Crypto.com is attractive because it defines a space where billions of dollars are changing hand with the amount growing annually,” Ron Jackson, the editor of Domain Name Journal, said in an email. “I think it is definitely a 7-figure domain name. Rare to see $5-$10 million these days but I wouldn’t be shocked if it did hit $5 million.”

That’s a lot of money for anyone, and the offers have been pouring in. Blaze tweeted in January that a hopeful buyer had called his university trying to get ahold of him. “Note to the idiot who hassled my department receptionist about wanting to buy my domain. It’s not for sale,” he wrote. “And if it were for sale, it definitely wouldn’t be for sale to you.” Although the frothy market for domains peaked in December when the price of Bitcoin hit $20,000, Blaze has been getting inquiries for a while. “Just got angry email from someone who wants to buy my domain (not for sale, btw) insisting I must sell it because capitalism,” he tweeted last June. “If you want my domain bc you’re speculating on crypto currency, just send me all your bitcoins instead. I promise to lose them for you.”

The “crypto” in Blaze’s domain name is a reference to cryptography, a long-standing shorthand in the information security community. (See “don’t roll your own crypto,” a common aphorism that refers to the riskiness of developing new encryption methods instead of using established ones, as just one example.) People outside the cryptography community started using “crypto” to refer to Bitcoin and its descendants, however, as a flood of cryptocurrencies debuted over the last year.

This new colloquial use of “crypto” caused consternation in security circles. “On the internet, ‘crypto’ has always been used to refer to cryptography,” wrote Motherboard cybersecurity reporter Lorenzo Franceschi-Bicchierai. “Think, for example, the term ‘Crypto Wars,’ which refer to government (originally the US government) efforts to undermine and slow down the adoption of unbreakable communications systems.”

Blaze himself scored a decisive blow in the Crypto Wars in 1994 when he discovered that the Clipper Chip, a device designed to allow the government to listen in on anyone’s phone calls, had a critical flaw that would allow criminals to circumvent its purpose. His paper about it, “Protocol Failure in the Escrowed Encryption Standard,” is available on crypto.com.

“I think calling cryptocurrencies ‘crypto’ is a poor choice, with bad consequences for both cryptography and cryptocurrencies,” he wrote on Twitter. “That doesn’t mean I’m some kind of language prescriptivist, and your saying that ‘language evolves’ or other such prattle doesn’t invalidate my concerns.”

In response to this attitude and his refusal to sell his domain, Blaze has been told that he is shortsighted, doesn’t deserve the domain, or is just bitter that he didn’t get on the lucrative cryptocurrency train earlier. One Twitter user told Blaze he is “greatly under-utilizing an incredible asset and defacing it with political nonsense that would make CNN proud” before adding “don’t be afraid to ask for $30+ million.” Another Twitter user advised Blaze to hold out for a billion.

Earlier this month, Blaze added a disclaimer to his website. It says: “This site does not trade in or provide services related to cryptocurrencies. It is concerned with cryptography, computer and network security, and technology policy research. Warning: Many cryptocurrencies are scams, and I strongly advise against their use as investment vehicles.”

This isn’t the first time Blaze has had to defend his domain. In 2000, amid the dot-com frenzy, a Delaware company calling itself Crypto.Com, Inc. started pitching “a new keyless encryption technology for secure communications on insecure circuits.” Blaze posted a statement on crypto.com calling the claims “extravagant” and noting that he has no affiliation with the company. He also pointed to cryptographer Claude Shannon’s proof of perfect secrecy, which showed unbreakable encryption over “insecure circuits” requires the use of a key. As they say, don’t roll your own crypto.