The FBI is asking for more than $20 million in the 2018 fiscal year budget to counter what the bureau sees as the threat of encryption, both in devices and in real-time communications tools such as text or voice apps.

The request is part of the Department of Justice’s proposed budget for the next fiscal year, and Deputy Attorney General Rod Rosenstein said during a Senate hearing Tuesday that the FBI would use the money for a wide variety of things. In his testimony, Rosenstein said that the increased use of encryption, which the FBI and other law enforcement agencies refer to as the problem of “going dark”, is a growing challenge and needs funding support.

“The seriousness of this threat cannot be overstated. ‘Going Dark’ refers to law enforcement’s increasing inability to lawfully access, collect, and intercept real-time communications and stored data, even with a warrant, due to fundamental shifts in communications services and technologies,” Rosenstein said.

“This phenomenon is severely impairing our ability to conduct investigations and bring criminals to justice. The FBI will use this funding to develop and acquire tools for electronic device analysis, cryptanalytic capability, and forensic tools.”

In the proposed budget, the FBI asked for $21.6 million to address the encryption issue. As Rosenstein said in his testimony, the money may be used for developing or buying tools and techniques to analyze encrypted devices, perform forensic analysis, or cryptanalytic analysis, all of which are time consuming and expensive. While the FBI has been raising concerns about the use of encrypted communications for years, much of the current concern comes from the proliferation of encrypted communications apps and devices that store user data in encrypted form by default.

Most current iPhones and Android devices have encrypted data storage enabled by default, and law enforcement agencies have struggled to bypass the protections. During the tense showdown between Apple and the FBI last year over an encrypted iPhone used by a terrorist, the bureau sought a court order to get Apple to build a backdoored version of iOS specifically to bypass the device’s encryption. Apple officials called the request offensive and fought it. Eventually the FBI bought a technique from a third party to unlock the phone.

But that case was just one of many involving encrypted devices, and FBI officials and others in the law enforcement community have continued to push for methods to bypass or weaken encryption systems, both in transit and at rest. Privacy advocates and security experts have pushed back, saying that any backdoored or intentionally weakened encryption system would put all users at risk.