The document, a European Council survey of member countries' views on encryption regulation, offered officials' behind-the-scenes opinions on how to craft a highly controversial law to stop the spread of child sexual abuse material (CSAM) in Europe.

The proposed law would require tech companies to scan their platforms, including users' private messages, to find illegal material. However, the proposal from Ylva Johansson, the EU commissioner in charge of home affairs, has drawn ire from cryptographers, technologists, and privacy advocates for its potential impact on end-to-end encryption.

For years, EU states have debated whether end-to-end encrypted communication platforms, such as WhatsApp and Signal, should be protected as a way for Europeans to exercise a fundamental right to privacy -- or weakened to keep criminals from being able to communicate outside the reach of law enforcement.

Experts who reviewed say it provides important insight into which EU countries plan to support a proposal that threatens to reshape encryption and the future of online privacy. Of the 20 EU countries represented the majority said they are in favor of some form of scanning of encrypted messages, with Spain's position emerging as the most extreme.

"Ideally, in our view, it would be desirable to legislatively prevent EU-based service providers from implementing end-to-end encryption," Spanish representatives said in the document. 

In its response, Spain said it is "imperative that we have access to the data" and suggests that it should be possible for encrypted communications to be decrypted.

Spain's interior minister, Fernando Grande-Marlaska, has been outspoken about what he considers the threat posted by encryption. When reached for comment about the leaked document, Daniel Campos de Diego, a spokesperson for Spain's Ministry of Interior, says the country's position on this matter is widely known and has been publicly disseminated on several occasions.

Edging close to Spain, Poland advocated in the leaked document for mechanisms through which encryption could be lifted by court order and for parents to have the power to decrypt children's communications.

Several other countries say they would give law enforcement access to people's encrypted messages and communications.