How to use 2-factor auth on mtgox, even without a smartphone

[bitcoinBull]

So, bitcoins are now probably the most wanted target of hackers and trojan-botnet operators in search of easy profit. They are the most easily monetized score of digital theft, valued at face in BTC while credit card numbers are sold for pennies on the dollar.

Every time you download programs, or re-install windows using that iso you got a from a torrent, chances are ever greater that there is a trojan/virus. The chances are also good that it will go Fully UnDetected by most, if not all, Anti-Virus programs (botnet operators use a "FUD crypter" for this). If so, your mtgox password will be captured and added to the botnet database of login/password form submissions.

Then dude takes your mtgox funds.

I lost roughly 2000 USD from my MT.Gox account at 08:40 JST on the 31th of may 2012.

A lot of that going on.

"MtGox account got cleared out"
 - http://bitcointalk.org/index.php?topic=85533.0

"All BTC disappeared from my Mt. Gox account"
 - http://bitcointalk.org/index.php?topic=88368.0

Another:
 - http://bitcointalk.org/index.php?topic=80562.msg941759#msg941759

And another:
"My mtgox account got compromised, what can I do?"
 - http://bitcointalk.org/index.php?topic=84585.0

And on other services as well.  Here same thing happened to some GLBSE users:
 - http://bitcointalk.org/index.php?topic=84893.0

In none of these was the person using multi-factor authentication.  Mt. Gox has had Yubikey support for a while.  Mt. Gox accounts now support Google Authenticator:
 - https://mtgox.com/press_release_20120605.html

But not you! Because you used 2-factor auth for withdrawals and dude only has your mtgox password, not your OTP private key.
 

Step 1:

Go to your mtgox security center and click "ADD NEW" under software authenticators.



Take a screenshot of this window, print it out, and lock it in a safe. Or copy/paste the secure private key and save it encrypted to a USB and lock that in a safe. Write it on a post-it, memorize it and then eat the post-it. Whatever you do, keep it secret but don't lose it.


Step 2:

If you have an android phone, install the google authenticator app for android. If you have an iOS device (iPod touch, iPad, iPhone), install the iOS app.

If you have neither, you can use this html5 google authenticator app. Download the zip file, extract it and open the index.html in your browser.

Now click the plus sign and add your secure private key. You are only running a local html5 app, so your secure private key is not being shared with anyone. You can even do this on an offline computer; you don't have to be online to use your secure private key to generate a one-time-passcode.




Step 3:

Use your generated one-time-passcode in the mtgox security center.



This passcode changes every 30 seconds. That's how long you have to type it into mtgox and "save" your new 2-factor auth system.




Step 4:

Add your new 2-factor method to "Withdrawal" to protect withdrawals.






Step 5:

Also add it to "Security Center". Otherwise, anyone with your login password can simply go to security center and remove your 2-factor auth protection.






Now a one-time-passcode is needed to remove 2-factor from withdrawals.



Step 6:

Your withdrawals are now protected.





CAVEAT on using the google authenticator html5 app:

Obviously, if you use your 2-factor "secure private key" on the same computer, it can be stolen along with the password. So pray that dude's trojan doesn't keylog everything, just login form passwords to sites like mtgox. Or use the google authenticator app on an offline computer. If you're ultra-paranoid, remember that your secure private key could be captured at set-up time when done on an insecure computer.

Also, the html5 app saves the secure private key to html5 localStorage, so click the (x) after use to remove it. Or clear it from the browser's cache/localStorage.

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[koin]

Or use the google authenticator app on an offline computer.

the clock on an offline computer will vary over time, which will make your otp give a bad result.  update the time manually if the otp is gives doesn't work.

[nedbert9]

This


This type of professional documentation for account security should have been developed by all the high profile Bitcoin sites that use Google 2FA.


It's a statement about their professionalism that they don't take the time to do this.

[markm]

This seems to assume you have a phone? Yet subject/title said even without one?

Is it that if you have no phone you have to get a yubikey instead?

-MarkM-

[phatsphere]

Is it that if you have no phone you have to get a yubikey instead?

if you have no phone, you can use the html5 app.

And if you don't have a graphical front-end at all (text-only terminal console), there is a python script on github that does the hmac hash calculation for you.

h

[sinner]

is there a way to use 2 factor auth on your bitcoin wallet?

[bitcoinBull]

Is it that if you have no phone you have to get a yubikey instead?

if you have no phone, you can use the html5 app.

And if you don't have a graphical front-end at all (text-only terminal console), there is a python script on github that does the hmac hash calculation for you.

h

btw, if you use that python script, you have to add padding to the "secure private key" mtgox provides (other google auth apps will accept the secret key without padding). So "RPAAJZCGOW7NSAAJCFRCCHIN44" with base32 padding becomes "RPAAJZCGOW7NSAAJCFRCCHIN44======".

Code:

>>> import hmac, base64, struct, hashlib, time
>>> import onetimepass as otp
>>> my_secret = "RPAAJZCGOW7NSAAJCFRCCHIN44======"
>>> otp.get_totp(my_secret)
956735

[foo]

Very cool, thanks for the guide. Put up a donation address and I will send you a few bitcents for your trouble.

I also found that the HTML5 app works in Opera Mobile, so I now have Google Auth on my Nokia (Symbian) phone!

[bitcoinBull]

Very cool, thanks for the guide. Put up a donation address and I will send you a few bitcents for your trouble.

I also found that the HTML5 app works in Opera Mobile, so I now have Google Auth on my Nokia (Symbian) phone!

You're very welcome. tip jar: 1DUCK7StixdPxMCia8qgqQ6zoaGRdGRnqU

[buddrulez]

NIce work on the tut very handy ifor! I will throw some your way aswell soon thanks!

[Hasimir]

As an alternative to deleting the entry (on computers rather than phones) when you're done, just store the entire GAuth directory on an encrypted volume (e.g. TrueCrypt) and only mount it when you need it.

[bitcoinBull]

As an alternative to deleting the entry (on computers rather than phones) when you're done, just store the entire GAuth directory on an encrypted volume (e.g. TrueCrypt) and only mount it when you need it.

That's a good idea, but it won't work. The GAuth page/app uses html5 localStorage, so the entry/"secret key" gets saved to the browser's data/cache folder, not to the folder with the GAuth html and javascript files.

You could edit the GAuth javascript file and replace the hardcoded example alice@google.com. Then it would be contained in the Gauth folder.

[Hasimir]

btw, if you use that python script, you have to add padding to the "secure private key" mtgox provides (other google auth apps will accept the secret key without padding). So "RPAAJZCGOW7NSAAJCFRCCHIN44" with base32 padding becomes "RPAAJZCGOW7NSAAJCFRCCHIN44======".

Code:

>>> import hmac, base64, struct, hashlib, time
>>> import onetimepass as otp
>>> my_secret = "RPAAJZCGOW7NSAAJCFRCCHIN44======"
>>> otp.get_totp(my_secret)
956735

Yep, that works.  Is there a way to report the number of seconds the OTP is valid for?  I can only see the check for whether it's true or false (and invoking that in the same script will always return true).

[Hasimir]

As an alternative to deleting the entry (on computers rather than phones) when you're done, just store the entire GAuth directory on an encrypted volume (e.g. TrueCrypt) and only mount it when you need it.

That's a good idea, but it won't work. The GAuth page/app uses html5 localStorage, so the entry/"secret key" gets saved to the browser's data/cache folder, not to the folder with the GAuth html and javascript files.

You could edit the GAuth javascript file and replace the hardcoded example alice@google.com. Then it would be contained in the Gauth folder.

Ah well, the Python script will be good enough for me.  Which takes care of that problem.

[Korbman]

Excellent tutorial, and well written. We should see more like this!

[Stephen Gornick]

Two-factor provides security when every withdrawal or security change (e.g., change password, e-mail address, remove two-factor, etc.) action will require a new OTP to be entered.

This is addressed in this thread:

A plea to exchanges ... lets do 2 factor right!
 - http://bitcointalk.org/index.php?topic=109424.0

If your exchange or EWallet provider claims to have two-factor but doesn't do two-factor right, let them know otherwise they'll continue thinking they are protecting their customers which can be even worse, due to having a false sense of security ("oh ya, I have two factor -- I'm safe storing even larger amounts there now!").

Here's a list of EWallets where two-factor is offered:
 - http://bitcoin.stackexchange.com/a/4114/153

[jborkl]

and a Gox yubikey is only $29 last time I checked.

They sent me one for free,  it is really I nice piece of hardware.

short press and long press. So you have built in additional press to withdraw

[no name]

Or use the google authenticator app on an offline computer.

the clock on an offline computer will vary over time, which will make your otp give a bad result.  update the time manually if the otp is gives doesn't work.

I tried to set 2fa on mtgox use this method via offlline computer (mini winxp on hirens boot usb) and get wrong otp. I had set  time and date same in second and get different otps. Online (same comp as mtgox session) generated otp well matched.

any advice, what is going wrong? thanks in advance!

[Hasimir]

Or use the google authenticator app on an offline computer.

the clock on an offline computer will vary over time, which will make your otp give a bad result.  update the time manually if the otp is gives doesn't work.

I tried to set 2fa on mtgox use this method via offlline computer (mini winxp on hirens boot usb) and get wrong otp. I had set  time and date same in second and get different otps. Online (same comp as mtgox session) generated otp well matched.

any advice, what is going wrong? thanks in advance!

This is most likely the clock creep issue.  The OTP only lasts for 30 seconds, so if the clock is wrong it will not be calculated for the correct time as observed by Mt. Gox.  The best solution is to use a system connected to a time (NTP) server, otherwise you'll have to update the clock manually.

[foo]

Or use the google authenticator app on an offline computer.

the clock on an offline computer will vary over time, which will make your otp give a bad result.  update the time manually if the otp is gives doesn't work.

I tried to set 2fa on mtgox use this method via offlline computer (mini winxp on hirens boot usb) and get wrong otp. I had set  time and date same in second and get different otps. Online (same comp as mtgox session) generated otp well matched.

any advice, what is going wrong? thanks in advance!

Wrong time zone on the offline computer?