Seán

I made a remote desktop connection to my work PC and from a few quick tests, these features are already implemented (version 1.0.116). I renamed a 7MB file and several seconds later the filename changed on my remote desktop screen. Normally it would take 3 minutes for a 7MB file to upload due to my sluggish DSL uplink at home (40KB/s max up). I copied a 8.6MB Zip file file into my shared folder on my home PC and copied the identical Zip file on work PC into the same shared folder straight away. A transfer briefly flickered in the 'Transfers' tab and the only thing that happened was that the time stamps were synced. For the modified file test, I added a small text file to that 8.6MB file on my home PC. A transfer appeared in the 'Transfers' tab for about 5 seconds and then got a 'Download complete' notificaiton on my work PC. I checked the Zip file there and it has the text file, so this pretty much confirms that it only transferred the difference to bring the Zip file on my work PC in sync. Edit: After a further file edit test, it seems like a partial sync is only done if matching contents of the file remain in the same spot at the other end. For example, when I deleted the first file in the 8.6MB zip file, BitTorrent Sync spent a few minutes re-uploading the file to my work PC. Basically, when I added the text file to the Zip file, everything else in the zip file remained the same as the text file data was simply appended to the end of the file, but when I deleted the first file, everything in the zip file would have been shifted towards the start of the file to fill the gap left over by the deleted file.

I would be interested in this feature also, as it would be very useful for sharing spare disk space between one or more friends or work colleagues to backup each other's selected folders and/or to improve sync performance, exactly like how BitTorent Sync does with sharing folders, but without anyone being able to view another user's files sync'd to their device. So basically when you would go to share a folder, in addition to the full access, read-only and 1-time secret options, there would be a encrypted no-access option, where sync'd files would remain encrypted at the other end. If let's say the device with the original shared folder has a hard disk failure and was the only device with the decrypted data, then the user would create a share on the replacement device using the full access secret and it would then sync with the device with the encrypted share, but as the encryption key is derived from the full access secret, the data would be decrypted to the replacement device. Another advantage would be that if your home internet connection goes down while at work, you could ask your friend or work colleague to switch on their computer with the encrypted share. As long as your data was already sync'd with their computer, it would sync with your work computer. Of course if your home PC + internet connection and their computer are both online, your data would also sync with your work computer a lot faster.

Personally I'd like it to work so I could do the following on my Android (v4.0.4) phone, i.e. first two being equivalent functionality to the desktop version: Sync my phone's 'Pictures' folder with a new folder on the PC, so everytime I take a picture, it's automatically on my PC. Same vice versa if I wish to take pictures with me to show on my phone. Sync my phone's 'Music' folder with a new folder on the PC. This could be 1-way, i.e. read-only folder on the phone, so when I add music to the folder on my PC, it's automatically added to the phone. Ability to select which shared folders to sync over the mobile network. For example, I would like to always have the pictures folder sync'd over 3G, but not other folders. Selective sync - For example, if one has a 10GB shared folder with a 100MB folder of important data inside, that this specific folder only could be synced to the phone. Another possible idea for the mobile version would be the ability to use it to cache data waiting to be synced with other devices (e.g. up to a user defined amount such as 200MB), which would be useful for users with a slow uplink at home and have their office PC switched off while out of the office. For example, if I add a 100MB of files to my shared folder, the mobile app would add this to its cache while the desktop version would sync as normal any other devices running BT Sync using the shared secret. If I head to work and switch on my PC, BT Sync would then start syncing as usual, but once it detects the mobile App on the network with the cached data, it would fetch this from the mobile App. If more data needs to be synced than the max cache size, then it would continue syncing the rest over the internet as usual.

Besides trust, one big potential issue would be getting malware that grabs the list of secrets, particularly with a large team of users, as the more devices there are with the same secret, the higher the chance one will get hit by malware, possibly without even the affected user knowing. Another possible way would be if the key is eavesdropped, for example, if anyone's e-mail account is compromised the hacker could do a search for any e-mail containing a BT Sync secret. Certificate based authentication/authorisation is one way to go, but instead of using an major certificate authority, one option would be to allow one device to run as a master with a private certificate authority, like with Windows Server. Off hand I cannot think of any other way of preventing unwanted key sharing. For example, if MAC address authentication is used, the malware would just need to read the MAC address so the hacker can spoof it. On the other hand, if MAC address, device ID, etc. authentication is used, BT Sync could throw a security warning if two different IP addresses connect with the same MAC address or identification method and cause all clients to discontinue sharing until the secret is changed.

At least this confirms one thing on my wishlist. I'm also sure glad to see it does not depend on user accounts. For example, to set up Dropbox, Google Drive, etc. with a team of users, every user requires their own account first, then sharing a folder between users and of course a hefty purchase for a team account. Where as with BitTorrent Sync, just install BT Sync and create a shared folder on each user PC with the matching shared secret. So much easier to set up and no ridiculously priced team account required either.

My wishlist is as follows: Ability to prioritise syncing by file size, e.g. where it syncs the smallest file, then the next smallest and so on until the biggest file is synced last. Also, if a smaller file is changed/added while syncing a large file, pause the large file until the smaller file is synced.Choose which share folders to display 'Download Complete' notifications for. For example, I have my mother's Documents folder sync'd 1-way to a backup folder on my PC. Every time she imports her photos, saves a document, etc. I get tray notifications. If I turn off notifications, I'm no longer notified if files in other shared folders are modified, such as if I share a folder with a work colleague.Add file versioning. A workaround at the moment for Windows Vista/7/8 PCs is enable 'Previous Versions' on the HDD containing the shared folder.Keep this sync utility freeware. This is my third day with the Alpha and already really impressed with it. So far syncing between my home PC, laptop and work PC works great and based on looking at my home PC via Remote Desktop from work, it appears to sync quicker than Dropbox. I much look forward to doing away with Dropbox once this reaches a stable release.