create key in backend at "any local dir" failed: Calibrate: scrypt.Calibrate: scrypt: the parameters provided are invalid

[wdl1908]

Output of restic version

restic 0.3.0 (v0.3.0-29-g190673b)
compiled at 2016-11-15 21:58:36 with go1.7.3 on linux/386

Expected behavior

create a new repo

Actual behavior

create key in backend at "any local dir" failed: Calibrate: scrypt.Calibrate: scrypt: the parameters provided are invalid

Steps to reproduce the behavior

1. build according to readme
2. ./restic init -r "any local dir"

replace "any local dir" with anything on the local filesystem
I tried several different dirs also with the root user. The result is always the same.

[fd0]

Hey, thanks for reporting this. I find it really unexpected. What happens here is that restic calibrates scrypt(), a function to derive encryption keys from a password, according to the hardware it is executed on. After calibration restic checks that the parameters are strong enough, otherwise default parameters should be used. Somehow this doesn't work, so we need to find out why.

What hardware do you run restic on? Is that especially low- or high-end (in terms of CPU)?

[wdl1908]

Intel(R) Core(TM)2 Quad CPU Q8400 @ 2.66GHz
8G RAM
Linux wormhole 4.6.0-1-686-pae #1 SMP Debian 4.6.4-1 (2016-07-18) i686 GNU/Linux

So yes maybe this is a low end machine.

[fd0]

Hm, that's not what I would call "low-end" ;)

I'll write something up so we can debug this further.

[wdl1908]

I tested it on a 64bit system and it seems to work fine the 32bit system always fails. Maybe there is some 64 bit specific code that fails on 32bit.

[fd0]

Ah, that's an interesting information! I can reproduce it (on my amd64 machine) when building and running a 32 bit restic binary:

$ go run build.go --goarch 386
$ ./restic -r /tmp/foo init                      
enter password for new backend: 
enter password again: 
create key in backend at /tmp/foo failed: Calibrate: scrypt.Calibrate: scrypt: the parameters provided are invalid

[fd0]

I've found the cause and implemented a solution, it was caused by an integer overflow in the Calibrate function of the simple-scrypt library, issue is here: elithrar/simple-scrypt#6

[wdl1908]

Nice you got a specific branch I can test?

[fd0]

I'll create one once the PR is merged :)

[fd0]

See branch fix-676 and #678

[wdl1908]

Yup that fixes the problem.

[fd0]

Great, thanks for having a look!

[cschelcher]

Hi All,

Thanks for fixing this for oldies 32bits systems ;)

However, vendor version on master is not up-to-date with master (including the fix) of source repository. I tested the fix with sucess though.

Could you please update vendor on restic master repo ?

Thanks for your great work ;) !

[fd0]

That is probably because we've recently switched to a different repo layout and are now using dep for vendor management. I'll bug the author to make a new release and make a PR which updates the version.

[fd0]

Done, the code in master uses simple-scrypt master.