An example operation may include one or more of receiving a request to verify a first encrypted document from a computing device, retrieving a second set of encrypted tokens of a second encrypted document from a blockchain, determining a similarity value of the first encrypted document with respect to the second encrypted document based on a first set of encrypted tokens in the first encrypted document and the second set of encrypted tokens in the second encrypted document, and outputting the determined similarity value to the computing device in response to the request.