For a general description of public key encryption and how it differs from the secret key variety, please see last month's article at http://www.dominopower.com/issues/issue199909/encryption001.html. I'll cover the nuts and bolts of public key encryption here.

If you look through Lotus' developer documentation, you'll find very little about public key encryption. What you do find will apply to sending mail, not to saving documents in a database. This is because the Notes architecture assumes public key encryption will be used for mail and secret key encryption will be used for documents. I don't think this is stated anywhere explicitly, but it's certainly implied in the design.

Fortunately, we can use an undocumented feature to encrypt saved documents with public keys. The process differs depending on whether your users have the R4 or R5 client. I'll cover the R5 procedure first because it's simpler.

As is always the case with undocumented features: tread at your own risk. Features are often undocumented because they don't work reliably, may change measurably in future releases, or may vanish without notice.

R5 Public key encryption
To set up R5 public key encryption, you'll use almost the same procedure I described last month for secret key. Let's go back to the Human Resources database example (if you're not sure what this example is, check out last month's article first). The HR department wants to track each employee's name, department, job title, salary range, and current salary, as shown in Figure A.

FIGURE A


The Employee form contains attributes which describe each employee. Roll over picture for a larger image.

Say we want to limit access to the SalaryRangeLow, SalaryRangeHigh, and CurrentSalary fields. First select a field to encrypt. I'll start with SalaryRangeLow. Double-click it to bring up the Field Properties dialog. Click the Options (beanie) tab, and at the bottom of the window under Security options, select "Enable encryption for this field", as shown in Figure B. Repeat this step for each field on the form you want to encrypt, for example SalaryRangeHigh and CurrentSalary.

FIGURE B


Enable encryption in the Field Properties dialog for each field you want to encrypt. Roll over picture for a larger image.