A computer based method of protecting sensitive documents is provided, the method comprising identifying a first document, generating a registration key associated with the first document, identifying a second document, generating a production key associated with the second document, and producing an alert if a segment of the production key is identical to a segment of the registration key. For example, the registration key may comprise a digital fingerprint and registration metadata and the production key may comprise a digital fingerprint and production metadata, and the method may produce an alert of the digital fingerprint of the production key matches the digital fingerprint of the registration key.