Encrypted "--reverse" filenames are always different

[borisbrodski]

I'm using encfs to create encrypted backup using following mount cmd:

encfs --extpass='/bin/bash -c "cat /root/.private/encfs-password"' --reverse /media/HDD /media/HDD-encfs --public

It works fine (besides too long filenames) for the initial backup. But incremental backups are impossible due to the fact, that each time I restart my machine and execute encfs ... -reverse ... using the same password and the same .encfs6.xml again, I get different filenames and most probably also different encrypted content.

Reading man page and googling I found no way to somehow fix random "salt" or "seed" in place, to make encfs always encrypt data in the same way.

Reproduction:

$ encfs --reverse /media/HDD /media/HDD-encfs --public
$ ls -1 /media/HDD-encfs
,Q053BzFjMwl,rTuaTKKOf1h9maHjbce,V6OCQivamZTd1
.
..
6us3Gp7-0dDyG8iimpY8LgnN
AFIrvoPetkjN6-6-pYkC,9t4
Xs3w-rSwjDq79h2j3XQNz6gZ
$ encfs -u /media/HDD-encfs
Filesystem unmounting: /media/HDD-encfs
$ encfs --reverse /media/HDD /media/HDD-encfs --public
$ ls -1 /media/HDD-encfs
,Wutuamh41
.
..
MYkuiSJV9phMLWAzB0dvtTo1
YfumyAM6y,
y7ViwnRaMZiDud57

Example .encfs6.xml to repoduce the problem:

?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE boost_serialization>
<boost_serialization signature="serialization::archive" version="7">
    <cfg class_id="0" tracking_level="0" version="20">
        <version>20100713</version>
        <creator>EncFS 1.9.5</creator>
        <cipherAlg class_id="1" tracking_level="0" version="0">
            <name>ssl/aes</name>
            <major>3</major>
            <minor>0</minor>
        </cipherAlg>
        <nameAlg>
            <name>nameio/stream</name>
            <major>2</major>
            <minor>1</minor>
        </nameAlg>
        <keySize>192</keySize>
        <blockSize>1024</blockSize>
        <plainData>0</plainData>
        <uniqueIV>0</uniqueIV>
        <chainedNameIV>0</chainedNameIV>
        <externalIVChaining>0</externalIVChaining>
        <blockMACBytes>0</blockMACBytes>
        <blockMACRandBytes>0</blockMACRandBytes>
        <allowHoles>1</allowHoles>
        <encodedKeySize>44</encodedKeySize>
        <encodedKeyData>XXXXX</encodedKeyData>
        <saltLen>20</saltLen>
        <saltData>XXXXX</saltData>
        <kdfIterations>159434</kdfIterations>
        <desiredKDFDuration>500</desiredKDFDuration>
    </cfg>
</boost_serialization>

[Pinkbyte]

Can you try to set 'saltLen' to 0?

[borisbrodski]

Unfortunately I can't reproduce this problem any more. It definitely occurred and skewed up my entire backup. I could reproduce it then again multiple times while posting this issue.

But later on without doing any upgrade or other change of any component on my system the problem disappears.