SecureExplore

From Globesoft:

SecureExplore developed by GlobeSoft is used to encrypt/decrypt files and/or whole directories from the Windows shell (e.g. Explorer.exe and Find.exe). The program uses a 128 bit secret key algorithm to let a user (or group of users) encrypt/decrypt sensitive information, that no one else should have access to. You can export a certificate and distribute it to other people within a group. The people in the group may then encrypt and decrypt files using that certificate.