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I need to split an USB flash disk into two USB drives, each one with its own drive letter, but one of these has to be hidden.

In the non-hidden partition I want to place my software, and in the hidden partition I need to place some files that are required by the software in order to work.

Moreover, only the software may read, write, delete or execute the files in this partition.

I thought to use a little partition viewed as a CD-ROM drive, as they do in many flash drives, but this solution does not allow to write other data in a second moment, and it's visible to the user that can read the file.

Obviously the software must be able to access to partition and read, write, delete or execute the content.

Is there a solution to do so, possibly that work also on Linux?

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What you want is technically impossible.

You want two partitions. One of the partitions is only accessible to the software that is stored on the drive. Impossible. This is because the computer that the USB drive is plug into uses it's OWN drivers to write to the USB drive, so thus it isn't constrained to file permission.

No software will ever meet your needs because it breaks the paradigm.

The best you can do is create a hidden partition that only Truecrypt can understand. It will still look like it has data, but it won't be discernible. But it will look like free space and you run the risk of other users overwriting it.

The only way to meet your write restrictions is to get a USB drive that has hardware implementation of write restrictions.

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You can always partition a thumb drive into multiple partitions... but I'm a bit confused as to what you mean by "hidden". Honestly... the only ways to implement a truly hidden partition are very difficult and dangerous to the data at best. With true-crypt, you can make an encrypted volume that exists as a file on the "un-encrypted" drive... which you can mount to a different drive-letter... and there are ways to partition the thumb-drive and leave 1/2 of it marked as free-space... which actually contains an encrypted volume. The risk is... because it appears as free-space it might accidentally get overwritten in a dozen different ways. I've even seen a 3rd option done... where you have a true-crypt volume file on the un-encrypted space... and in the true-crypt volume.. you have it split into two partitions where the 1st is treated normally... and the 2nd is marked as free-space... which contains a 2nd true-crypted volume... which would need to be mounted as a 3rd drive.

If you're going to that level of trying to hide your data... you're doing something wrong. (either technically, or morally. I hope it's not the latter)

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Thank you for answer, i know truecrypt and it's a very good tool, but with the encryption as a file on the visible drive, there is the risk of an accidental delete (for ex formatting the drive). What i need instead is a drive accessible in read/write only from the software but not from the user. Like with linux file permission, the only owner need to be the software without the possibility to change this setting. About the mean of the term hidden, i don't need a truly hidden partition, but only the possibility to make this data invisible. – Francesco Jul 29 '11 at 17:41
Format the volume using NTFS & use the NTFS-ACLs... admittedly, if the OS isn't running, you can bypass the permissions (in linux/etc...) but this should work for basic office/desktop usage. You can also look into bitlocker (built into windows) for encryption... but this can be more frustration than it's worth. – TheCompWiz Aug 2 '11 at 15:08

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