On 1/24/21, professor rat
David Chaum Elixxer net boasts this ...
https://techraptor.net/technology/news/encryption-expert-proposes-backdoor-c...
"Chaum has devised a system which he believes will allow governments to decrypt communications of criminals without allowing mass surveillance. "
Decryption of messages on the network can only occur through the cooperation of nine separate servers.
The key with approaches like that is to require one of the individuals decrypting the messages be one of the people involved in sending or receiving or being acted on by (which is posisble on a blockchain) them. Then when decryption is needed to handle crime, it only works if a victim or participants in that crime are involved. If nobody involved in it wants it decrypted, it's not enough crime to decrypt.