Issue:
Use of RMCE-encrypted exFAT media created on macOS Catalina on Windows devices will incur an abnormally-long Media Close process on the Windows Device.
Cause:
This is due to certain differences in how macOS writes the container's file size information, compared to how Windows does the same thing.
Upon closing such a Catalina-created Container, or performing any other function (e.g. Challenge-Response) on an ExFat media, the Windows device will attempt to "correct" what it sees as a size discrepancy issue, and this process can take a great deal of time.
Recommendation:
At present, customers creating Container-Encrypted media on media formatted using ExFAT are cautioned to not use that media on Windows devices.
Note: If it is imperative that customers use macOS Catalina-created exFAT Container-encryped media on a Windows machine, they are warned that the process of closing the macOS Catalina-generated RMCE media on the Windows device can incur a very long wait while Windows "pads out" the space used by the Container so that Windows will see the space used by the media is congruent.
Side-Benefit of waiting it out on Windows devices: Although this process may take something like 1/2 hour for a 16GB USB media, once Windows has "fixed" what it sees as non-congruent file size attributes, the Container-encrypted media should be fully Mac/Windows interchangeable without needing to be "fixed" again, so the slow process cost should not be incurred during a second or subsequent use of the same media.
Detailed discussion of this issue, and solutions considered:
In response to customer complaints regarding how long the formatting step could take on macOS Devices, WinMagic had implemented fast-formatting for exFAT drives on macOS when creating container-encrypted media some versions ago. However, under macOS Catalina, this causes aspects of the media size to be seen as not congruent when the media is used in Windows, and Windows starts to "fix" it which takes a long time.
Due to differences in macOS Catalina security compared to earlier versions of macOS, WinMagic considered (and rejected) the following options to avoid this problem:
- Roll back to using the slower formatting, which does not experience this issue, but will cost additional time for all customers when creating container-encrypted media on the macOS platform. This was rejected since most customers will upgrade to Catalina if possible, so all customers would be penalized by extended formatting times.
- Find a solution to this issue. SecureDoc developers developed a patch which works well on all other macOS versions such as Mojave, High Sierra and Sierra, but does not work on macOS Catalina (due to its higher level security).
- Solve the problem in Catalina. A solution had been found, but it was decided that the inconvenience to macOS Catalina users would be too great. It was rejected because a) it requires that the user be logged into an Administrator account, and b) it requires that the user must intervene 2-3 times per item of media to either click "Allow" or to enter a password.