4 ms·

I don't profess to know much about security, but unless TrueCrypt does block-level encryption, AND dropbox does block-level syncing, wouldn't this scheme work o

by iam 16y ago

I don't profess to know much about security, but unless TrueCrypt does block-level encryption, AND dropbox does block-level syncing, wouldn't this scheme work out really poorly for storing large TrueCrypt volumes?

foxhop 16y ago
That is a great question, If you find the answer let me know. At this point I have been playing around with 700mb file volumes. When I make an addition to the volume, it takes about 2 minutes to sync. I have not tested deletions yet.
- hedgehog 16y ago
  I used to store use TrueCrypt + Dropbox to store some important files. Dropbox will detect and sync only the changed portions of your TrueCrypt volume. It takes a while (I think it does some sort of rolling checksum thing to detect differences so it has to read through the entire thing locally) but works ok. It would only sync when the volume was unmounted though.
psykotic 16y ago
Assuming a strong form of encryption with minimal information leakage, avalanching would imply that flipping even a single bit of plaintext in a volume of N bits would force ~N/2 bits of ciphertext to change with a distribution approaching maximum entropy. Flipping any number of bits should have the same statistical effect. Of course, that's infeasible for file system encryption and isn't how TrueCrypt works. An idea is to use a one-to-one mapping between TrueCrypt blocks and DropBox files. Write a file system watcher script that picks up changes to files in the DropBox folder and mirrors the changes to the corresponding blocks in a TrueCrypt volume that lives outside the DropBox folder. The other way around, too. Do you see anything obviously wrong-headed with this approach? I admittedly don't know the details of TrueCrypt's crypto. If it already does file-level rather than block-level encryption, these tricks wouldn't be necessary. But file-level encryption would seem to leak way too much information to satisfy the truly paranoid.

by iam 16y ago

foxhop 16y ago

That is a great question, If you find the answer let me know. At this point I have been playing around with 700mb file volumes. When I make an addition to the volume, it takes about 2 minutes to sync. I have not tested deletions yet.

hedgehog 16y ago
I used to store use TrueCrypt + Dropbox to store some important files. Dropbox will detect and sync only the changed portions of your TrueCrypt volume. It takes a while (I think it does some sort of rolling checksum thing to detect differences so it has to read through the entire thing locally) but works ok. It would only sync when the volume was unmounted though.

psykotic 16y ago

Assuming a strong form of encryption with minimal information leakage, avalanching would imply that flipping even a single bit of plaintext in a volume of N bits would force ~N/2 bits of ciphertext to change with a distribution approaching maximum entropy. Flipping any number of bits should have the same statistical effect. Of course, that's infeasible for file system encryption and isn't how TrueCrypt works. An idea is to use a one-to-one mapping between TrueCrypt blocks and DropBox files. Write a file system watcher script that picks up changes to files in the DropBox folder and mirrors the changes to the corresponding blocks in a TrueCrypt volume that lives outside the DropBox folder. The other way around, too. Do you see anything obviously wrong-headed with this approach? I admittedly don't know the details of TrueCrypt's crypto. If it already does file-level rather than block-level encryption, these tricks wouldn't be necessary. But file-level encryption would seem to leak way too much information to satisfy the truly paranoid.