In the US, police and prosecutors continue to say encryption—the use of math to protect data from outside eyes, including those of the government—presents a significant barrier to solving crimes or following leads.
Now, on the other side of the Atlantic, the head of Europe's law enforcement body is saying that encryption is an issue in the vast majority of cases the agency sees.
"Encryption dilemma must be solved soon. Real problem in 75% of all Europol cases," Rob Wainwright, director of Europol, tweeted on Sunday.
The tweet came in response to an op-ed written by John Naughton, a professor from the Open University, and published by the Guardian, that said an opportunity for more permanently addressing law enforcement's concerns around encryption had been lost during the FBI and Apple legal fight in San Bernardino.
"The use of anonymisation and encryption technologies is widening and is key issue for law enforcement in all criminal areas."
It is not clear what sort of encryption Wainwright was referring to; be that message encryption to secure communications, or hard-drive encryption that protects data stored on devices, which was the issue at hand in the recent Apple case.
When asked about it, Claire Georges from Europol's corporate communications answered broadly about technologies used by criminals, citing encryption, anonymisation tools such as Tor, and even implied that virtual currencies such as bitcoin are part of the problem.
"The use of anonymisation and encryption technologies is widening and is key issue for law enforcement in all criminal areas," she told Motherboard in an email.
"Technology in general is used not only by cybercriminals, but also by drug dealers, child sexual offenders and other criminals involved in different illegal activities. Encryption is commonly used in secure communications and is becoming a standard protection feature in many products, such as e-wallets for virtual currencies."
Georges also pointed to Europol's Internet Organised Crime Threat Assessment (iOCTA) from 2014, which reads "The use of anonymisation tools is ubiquitous amongst the cyber underground."
Responding to a question of whether backdoors are an avenue for law enforcement, Wainwright wrote in another tweet that "back doors not the solution but regulated front door access. Finding how is key question."
Security experts say any sort of "front door," even if designed only for law enforcement, would be vulnerable to exploitation from hackers and malicious actors, undermining the security of all devices that used it.
Encryption, in some cases, may present an issue for law enforcement. But lumping message and hard-drive encryption, along with technologies such as Tor, all into the same basket is not helpful for anyone; as each requires a unique response, all balancing privacy, security, and access for police.