Confidentiality is usually covered by the use of a Confidentiality Agreement or Non-Disclosure Agreement (NDA), which defines a set of rules or a promise limiting access or places restrictions on certain types of information. Areas that have legal agreements covering confidentiality are:
Legal Confidentiality
Medical Confidentiality
Clinical and Counseling Psychology
Commercial Confidentiality
Banking Confidentiality
Public Policy Concerns
Religious Confidentiality
As a rule of thumb, it is best to treat all Personal Identifiable Information (PII) as confidential and to secure it (i.e., require authentication both to access the data and log access to the data).
The US National Institute of Standards and Technology (NIST) describe the kinds of data that should be treated as PII1) as:
Name, such as full name, maiden name, mother‘s maiden name, or alias
Personal Identification Number (PIN), such as:
• Social security number (SSN),
• Passport number,
• Driver‘s license number,
• Taxpayer identification number,
• Patient identification number,
• Financial account number, and
• Credit card number
NIST also identifies information which potentially can be used to identify people:
Address information, such as street address or email address
Telephone numbers, including mobile, business, and personal numbers
Personal characteristics, including photographic image (especially of face or other distinguishing characteristic), x-rays, fingerprints, or other
Biometric image or template data (e.g., retina scan, voice signature, facial geometry)
Information identifying personally owned property, such as vehicle registration number or title number and related information
Information about an individual that is linked or linkable to one of the above (e.g., date of birth, place of birth, race, religion, weight, activities, geographical indicators, employment information, medical information, education information, financial information).