The Financial Crimes Enforcement Network — a unit within Treasury that guards against money laundering — requested comments on the proposed rules, saying they were aimed at closing loopholes that can be exploited.

“The rule, which applies to financial institutions and is consistent with existing requirements, is intended to protect national security, assist law enforcement, and increase transparency while minimizing impact on responsible innovation,” Treasury Secretary Steven Mnuchin said in a statement.

Concerns over money laundering and the ability of financial firms to know the identities of their crypto clients have been at the forefront as Washington has weighed how to regulate digital assets. While critics say that instruments like Bitcoin make the illicit transfer of funds easier, crypto advocates say that the network of digital ledgers known as the blockchain allows money to be traced more easily than cash and can actually help law enforcement.

The Treasury said it will take public comment for 15 days on the plan, which is certain to draw widespread criticism from the cryptocurrency industry. The added restrictions would place a series of new burdens on crypto exchanges and other firms involved in the transfer of digital assets.

The focus of the rule is on so-called unhosted wallets that are not held on a registered exchange or by a bank. The new regulation would effectively require exchanges sending money to one of these self-hosted wallets, which are not held in an exchange or bank, to take a series of compliance steps which could be costly and time consuming.

“The ability for individuals to engage in digital peer-to-peer transactions is the foundation of the crypto economy,” said Kristin Smith, head of the Blockchain Association. “Undercutting that ability with last-minute rulemaking in the twilight days of an outgoing administration is not the way to make the type of long-lasting, responsive regulations that will support the safe growth of this industry in the U.S.”