Room 40 1.0 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The application lies within Security Tools, more precisely Personal Security. According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software. The actual developer of this free software for Mac is SevenBits.
From the developer:
Room 40 is an encryption software program designed to keep your important data safe, secure, and away from prying eyes. Without Room 40, whenever you send important documents over e-mail, copy them to portable flash drives, or even let others use your computer, you are potentially giving unknown people a treasure-trove of personal data.
You may want to check out more software for Mac, such as No More Room in Hell, RingCentral Rooms or Room EQ Wizard, which might be related to Room 40.