#59 Endless encrption/decryption/sync cycle.

[Anonymous]

Originally created by: Luke.D.T... (code.google.com)@gmail.com
Originally owned by: tortoisesvn

I have been using Cryptsync with my Dropbox account for storing financial information for a few months and I love it! However lately (possibly after some sort of update) I have been having a strange problem.

What is happening is that there is an endless loop of syncing and re-syncing of a particular file between two machines. The file happens to be an MS Money sunset edition backup file. The two machines are not agreeing on what the encrypted file should be and they do this:

Machine A: New MS Money backup file in decrypted folder.
Machine A: Cryptsync crypts and syncs to Encrypted Dropbox folder.
Machine A: Dropbox uploads encrypted file
Machine B: Dropbox downloads encrypted file
Machine B: Cryptsync decrypts and syncs to decrypted folder
Machine B: (?) Cryptsync then re-encrypts the file back to Dropbox folder - not sure whether this is the case but it must do to see the behaviour I am experiencing. (?)
Machine B: Dropbox uploads new version of file different from the previous one

repeat Ad infinitum

If I download two copies of the encrypted file provided by the two machines from the version history in Dropbox and compare them in a hex editor, they are different even though the file is the same. The first 8 bytes are the same then the rest is different. Looking at the 7zip specification here: http://cpansearch.perl.org/src/BJOERN/Compress-Deflate7-1.0/7zip/DOC/7zFormat.txt, it appears that the first 8 bytes are the 7zip signature plus major and minor version bytes. Then the next header field showing a difference is the CRC.

If I manually "un7z" them and diff the decrypted files, they are identical.

For some reason one machine is encrypting the file differently than the other. Both machines are running the same version of Cryptsync (1.0.9 x64) and both running Windows 7 x64. In case it matters they are also both running the same version of 7zip (9.20 x64).

Another strange thing is that this only seems to happen for MS Money backup files and no other files.

Maybe the encryption uses some randomness which explains the difference, then that would lead to the question of why cryptsync is re-encrypting the file on both machines.

[Anonymous]

Originally posted by: Luke.D.T... (code.google.com)@gmail.com

Dropbox history screenshot attached...

[Anonymous]

Originally posted by: tortoisesvn

CryptSync relies on the last-modified-time of a file to determine whether it needs en/decrypting.
Can you check those on that file?
Is there maybe another application that changes the last-modified-time of that file? (maybe a shell extension that opens the file in read mode?)

[Anonymous]

Originally posted by: doctore... (code.google.com)@gmail.com

i have the same issue and the issue completely disappear if i used dropbox directly.

[Anonymous]

Originally posted by: Luke.D.T... (code.google.com)@gmail.com

I have no services that are changing the files. In fact, it seems to have disappeared now and I have no idea why.

[Anonymous]

Originally posted by: Luke.D.T... (code.google.com)@gmail.com

I spoke too soon it's back again. There are no services that are changing the modification time. In fact the modification time is not changing at all through the cycle.

Here is the log:
09/18/13 14:32:24 : Starting CryptSync
09/18/13 15:01:27 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_142513.mbf to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_142513.mbf.cryptsync
09/18/13 15:01:30 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_150026.mbf to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_150026.mbf.cryptsync
09/18/13 15:01:32 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset.lrd to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset.lrd.cryptsync
09/18/13 15:01:32 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset.mny to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset.mny.cryptsync
09/18/13 15:01:54 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset.mny to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset.mny.cryptsync
09/18/13 15:02:04 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset.mny to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset.mny.cryptsync
09/18/13 15:03:04 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset.mny to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset.mny.cryptsync
09/18/13 15:03:34 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_142513.mbf to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_142513.mbf.cryptsync
09/18/13 15:04:24 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset.mny to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset.mny.cryptsync
09/18/13 15:04:34 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_150026.mbf to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_150026.mbf.cryptsync
09/18/13 15:04:37 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset.mny to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset.mny.cryptsync
09/18/13 15:05:24 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset.mny to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset.mny.cryptsync
09/18/13 15:05:54 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_142513.mbf to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_142513.mbf.cryptsync
09/18/13 15:06:54 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset.mny to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset.mny.cryptsync
09/18/13 15:07:04 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_150026.mbf to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_150026.mbf.cryptsync
09/18/13 15:07:44 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_142513.mbf to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_142513.mbf.cryptsync
09/18/13 15:09:04 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_150026.mbf to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_150026.mbf.cryptsync
09/18/13 15:09:54 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset.mny to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset.mny.cryptsync
09/18/13 15:09:57 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_142513.mbf to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_142513.mbf.cryptsync
09/18/13 15:11:14 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_150026.mbf to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_150026.mbf.cryptsync
09/18/13 15:12:24 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_142513.mbf to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_142513.mbf.cryptsync
09/18/13 15:12:34 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset.mny to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset.mny.cryptsync
09/18/13 15:12:44 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset.mny to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset.mny.cryptsync
09/18/13 15:13:24 : encrypt file D:\Decrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_150026.mbf to D:\Dropbox\Encrypted\Finance\MS Money\Luke MS Money sunset AutoBackup_2013-09-18_150026.mbf.cryptsync

A screenshot of Explorer showing the modification times is attached.

[Anonymous]

Originally posted by: mas... (code.google.com)@gmail.com

Maybe I can reproduce this issue.
If I rename "dir1" to "dir2" then it re-create "dir1" (in a Truecrypt volume, I don't know if it's relevant). After that it moves back last modified files from dir2 to dir1 and endless cycle begins with those files.

[Anonymous]

Originally posted by: tortoisesvn

Try enabling the FAT workaround in the pair dialog (FAT filesystem workaround, reduces write time detection to two seconds)

[Anonymous]

Originally posted by: tortoisesvn

I'll increase the hysteresis of the FAT workaround...

Labels: Milestone-1.1.5
Status: Started

[Anonymous]

Originally posted by: tortoisesvn

(No comment was entered for this change.)

Owner: tortoisesvn

[Anonymous]

Originally posted by: tortoisesvn

This issue was closed by revision [r244].

Status: Fixed

[Anonymous]

Originally posted by: tortoisesvn

Issue 84 has been merged into this issue.