Preserving privacy of digital communication information

A computer implemented method for verifying that information in a sender entity has been correctly recorded in a receiver entity, while preserving privacy by not revealing the information from the sender entity, comprising the following steps:

• a) encoding the information in the sender entity computer and sending the encoded sender information from the sender entity computer to a receiver entity computer;
• b) generating with the receiver entity computer a proof of content based on the encoded sender information, and sending the proof of content to the sender entity computer from the receiver entity computer;
• c) verifying information with the sender entity computer, to thereby make a verification, that the proof of content received corresponds with the information in the sender entity computer by comparing values of the proof of content received with values of a proof of content known in advance that correspond to the verified information;
• d) generating in the sender entity computer a further encoding of the information in the sender entity computer, and sending said further encoding to the receiver entity computer;
• and
• e) computing a similarity proof demonstrating that the encoding from step a) and the further encoding from step d) have been done with the information in the sender entity computer, without revealing the information from the sender entity, and sending said similarity proof to the receiver entity.