High granular multi-level-security model for improved usability

Working with existing multi-level-security (MLS) models reduces the usability especially when users try to transfer information to persons with different security categories. A main reason for the problems occurring with the information exchanging is that the existing MLS models assign a specific security level to documents. The assigned security level equals the highest security level of the textual content within the document. Based on the commonly used Bell LaPadula model, an extended model with an increased granularity is introduced. It is shown that users can access to parts of documents with higher security levels without causing a security compromise. This enables information exchange and it leads to an increased usability of the MLS model.