Abstract: Secure auditability of monitoring processing using public ledgers that are particularly useful for monitoring surveillance orders, whereby an overseeing enforcer (“E”) checks if law enforcement agencies and companies are respectively over-requesting or over-sharing user data beyond what is permitted by the surveillance order, in a privacy-preserving way, such that E does not know the real identities of the users being surveilled, nor does E get to read the users' unencrypted data. Embodiments of the present invention also have inbuilt checks and balances to require unsealing of surveillance orders at the appropriate times, thus enabling accounting of the surveillance operation to verify that lawful procedures were followed, protecting users from government overreach, and helping law enforcement agencies and companies demonstrate that they followed the rule of law.

Abstract: A method of sending content comprising receiving a membership request from a client at an anonymizer, the membership request being encrypted with a public key of the anonymizer, generating a table from a prefix-free source coding scheme with a full binary tree, a pseudonym range, and a master key, sending the table, the pseudonym range, and the master key, all encrypted with a public key of the client, receiving a content request with an encoded content name, the content request being encoded using the table, a pseudonym from the pseudonym range, and the master key, decoding the content name of the content request using the pseudonym, the table, and the master key, retrieving content corresponding to the content name, and sending the content and the encoded content name. Secure information sharing is also provided for.