Bitcoin Forum

10 characters, 20? 25?

Letters, numbers, special characters?

What if a user used only letters and numbers for example?





Say a hacker gets a wallet.dat with the pass-phrase helloworld, would it break in seconds? Now what if it is helloworld!~~ or HelloWorld!~~!

Are all these "weak" pass-phrases?


What if the wallet is than also backed up online which is known as a bad practice. What are the implications of that?

you can try this, to see how strong your password is

https://howsecureismypassword.net/

usually something with 10-12 is good enough, just change the combination for every site

I have a feeling that's not the right link lol.

This might be of better use: https://howsecureismypassword.net/

yeah you are right(your link was the one that i wanted to post), it's because i was arguing with another user on another forum about gpu consumption, i confused the two link

my bad  :D

If you make them NSA proof they are good enough.  :)
 
Edward Snowden on Passwords https://www.youtube.com/watch?v=yzGzB-yYKcc

Long passwords may be seen as "strong passwords" but they might not be.
For instance;
if you use english letters only 10 char password; there're 26^10 different possibilities.
260.000.000.000
if you use alphanumerical 10 char password; there're 36^10 different possibilities
360.000.000.000
if you use alphanumerical + special chars (let's say there's 20 different special char like /,*-?=_ etc) total 8 char password; there're  56^6 different possibilities
~1.736.000.000.000

Also check this;
https://open.bufferapp.com/wp-content/uploads/2014/06/password_strength.png

12 letter is enough, if you combine both upper & lower case, numbers and special characters.
See my wifi password below:
U,F4%rw$RE,.?54
this password might take years to brute force (even with super computers).
But the thing is you've to remember you password.
And change your password frequently.


~Rude Boy

Clicked on this link expecting to see the xkcd.com cartoon on entropy. Was not disappointed.

Thats cool, 143 billion years it will take to crack my password, now i better not forget it!

How secure is this website though, doesn't look all that professional, I'd be uncomfortable using a password I've tested on there.

I'd say a strong password is simply one that strays as far as possible from convention. Don't use words that are actual words, a mix of 20 letters, numbers and special characters should be enough to provide a reasonably strong password for at least the next 5 years (until computing power reaches new heights). The question then is how/where to store your password, I personally wouldn't trust any online storage service for this, a local storage device that cannot connect to the internet would be better. You can memorize just one super strong password (of course if you can memorize each individual password it would be even better) that leads to all your other passwords.

longer passwords are stronger for obvious reasons but it mostly depends on what site or service it is for. for a bitcoin wallet i suggest 20 characters. letters, symbols, numbers. don't use words, mix everything.

they said it specifically, to not use passwords that you would then use for your normal activity, use a similar one just for testing

Other responses have been pretty accurate so far. The only other thing I'd like to mention is that the passphrase or password that OP describes should not be confused with a NXT passphrase or a Bitcoin brainwallet passphrase. For the latter two, a far higher level of security is required since you are dealing with not just a single attacker but dozens and possibly hundreds of attackers distributed all over the world using precomputed rainbow tables which can crack wallets in a manner that is not computationally expensive.

For the typical wallet password you might use to unlock a Qt or Electrum wallet, 12-20 random characters with a combination of uppercase and lowercase letters, numbers, and symbols is usually considered to be sufficient for the short to medium-term future. Keep in mind that Moore's law* states that computing power will double every 18 or so months so a password that is considered sufficient today might not be sufficient 20 years from now.

For a NXT passphrase or Bitcoin brainwallet passphrase, you really don't want anything under 30-35 characters in length and 50+ character passphrases are usually recommended. Mine, for instance, is 560 characters in length with uppercase and lowercase letters, numbers, and symbols.

*Yes, I'm aware that some predictions show that Moore's law is slowing down and will cease to remain true in the future but that's just hypothetical at this stage and beyond the scope of this thread.

EDIT: And for those who say that you shouldn't use words, this is mostly true. However, a sufficiently long and randomly generated list of words from a large enough pool should be uncrackable by any brute force method. Some people might find a list of English words to be more memorable compared to traditional passwords. Electrum uses this method, and so does NXT. And while these programs use 12-13 words to generate their passphrases, a lower number (e.g. 10 words) might be sufficient for encrypting a wallet.dat file.


1,000 guesses per second isn't a good assumption given that a.) the comic assumes that you're target is a web service, and b.) modern computers are capable of better speeds than this anyway. I think an ordinary computer is capable of 50,000 guesses per second.

Aside: Great post, Bizmark13!

How fast an "ordinary" computer can try passwords varies greatly depending on the wallet software and the brute-forcing software. Here's a spreadsheet which has some comparisons of several popular wallets & two open source brute-forcers running on a mid-range quad-core desktop machine:

https://onedrive.live.com/redir?resid=584f122ba17116ee%21295 (https://onedrive.live.com/redir?resid=584f122ba17116ee%21295)

Guess rates vary between 20 per second (Armory, CPU only) all the way up to 4,000,000 per second (older blockchain.info wallets, GPU accelerated). Some wallets would be even faster (Electrum, MultiBit Classic) if an open source GPU accelerated version were available.

For Bitcoin Core, guess rates vary between roughly 40 and 2,000 per second depending on whether or not GPU acceleration is used (and of course depending on the CPUs and GPUs).

I would think that an encrypted wallet with a strong enough password should still be secure even when stored on the cloud although obviously it's not as secure as keeping it completely offline. Even if an employee from the hosting company found your wallet and attempted to crack it, your coins should still be safe if your password is strong enough.


I don't think that link accommodates dictionary attacks though. Putting "hello my name is" shows that it would take 2 billion years to crack it and "good morning" gives a result of 546 years. Obviously, neither of these are true.


Wifi passwords are notoriously easy to crack. I believe even WPA2 can be cracked in a few days. The underlying AES encryption standard is pretty secure but there are workarounds and vulnerabilities which can reduce the effort required to crack these passwords significantly.


Ah... You're right. Didn't realize it varied so much. The 50,000 figure was from a laptop I had a while ago performing SHA-256 decryption. Although I guess I should have realized it since the no. of encryption iterations and method of encryption used varies between different programs.

yeah it's a bit off, i found one that is much better https://www.my1login.com/content/password-strength-test.php

If you had a vault full of gold how strong would the password be to unlock it? And if you have $ 100 in your wallet how strong would the password be everytime you want to use your cash?

For your "safe" at home you'll want to use a very strong password and for your phone wallet you can use a weak password.

As long as we're talking about favorite strength checkers, here's mine: https://dl.dropboxusercontent.com/u/209/zxcvbn/test/index.html (https://dl.dropboxusercontent.com/u/209/zxcvbn/test/index.html)

It's the open source javascript-only checker used by Dropbox. There's a description of its strengths and weaknesses here: https://blogs.dropbox.com/tech/2012/04/zxcvbn-realistic-password-strength-estimation/ (https://blogs.dropbox.com/tech/2012/04/zxcvbn-realistic-password-strength-estimation/)

i don't know who is right, but with "my name is" the first that i posted say 3 hours, instead your say 1 year approximately

also it say crack time 35M seconds which is about 1 year and then crack time display 3 years? are those two not the same thing?

I agree, however "strong enough password" is a difficult thing to measure. Also, the list of transactions is not password protected for most wallets (there are exceptions).



WEP and Wi-Fi Protected Setup PINs are both completely broken, and have been for a number of years.

WPA1/2-TKIP (uses an RC4 cipher) has a number of weaknesses, including a practical data injection weakness and an almost-practical plaintext recovery weakness.

WPA1/2-CCMP (uses an AES-128 cipher) has no serious weaknesses, however it doesn't use a very good KDF which lends itself to offline brute-forcing attacks when weak passwords are used. This is especially true if a common SSID is also used (because it makes rainbow table based attacks possible).

(The AES cipher is believed to be very secure; there are no known practical attacks against it, although there are some concerns about the key scheduler in AES-192/256 (but not 128) possibly being vulnerable to related-key attacks one day; good news is that only poorly designed software uses related keys).

I don't understand.... when I try "my name is" in the one I linked above (zxcvbn), I get back 5 hours. More on point, it turns out the first one (my1login.com) is using the same underlying zxcvbn javascript library (but maybe a different version of it).

Regardless, the answer to "who is right" is: nobody. As the article I linked above discusses, estimating crack times of a password is very hard, and often attackers have access to resources (e.g. gigantic n-gram tables) which are just too impractical for javascript checkers like these to include.

Have a look at this, its quite good, but you should consider skipping substantial parts.
You should have all types of characters, which are:
1. Upper case
2. Lower case
3. Numbers
4. Special characters

Moreover, you should make it quite long

The search space increases with 20, 25. Bad guys use rainbow tables, dictionary attacks, brute force and everything they can find. Do not use phrases like 'helloworld' and little variations of that because they are compromised.  Expect bad guys to try 10.000 passwords or more per second. Some scientific papers on this issue:

All in a day's work: Password cracking for the rest of us
http://www.sintef.no/upload/IKT/9013/dayswork.pdf (http://www.sintef.no/upload/IKT/9013/dayswork.pdf)

Password Strength: An Empirical Analysis
http://www.eurecom.fr/~michiard/downloads/infocom10.pdf (http://www.eurecom.fr/~michiard/downloads/infocom10.pdf)

Proactive Password Strength Analyzer Using Filters and Machine Learning Techniques
http://www.ijcaonline.org/volume7/number14/pxc3871788.pdf (http://www.ijcaonline.org/volume7/number14/pxc3871788.pdf)

The conclusion of one of the papers:

Pick a password as random and long as a bitcoin address and you should be good for now.

If you have backed up online then at least one person other than you has access to your wallet file.

I admit I didn't read the referenced papers, however that conclusion is ridiculous. A simple 8+ byte random salt as already used by most* Bitcoin wallet software today easily defeats rainbow table attacks.

* Electrum (1.x and 2.x) and MultiBit HD are two notable exceptions of wallets which don't use salt.

this is a cool link, i bookmarked it for later references. and according to it the kind of passwords i use will require 8 quintillion years to be cracked by a desktop pc :D

The kind of passwords I use:


"It should be pretty safe." :)

...and...


Don't put your faith in password estimators (read the rest of this thread), but if you insist on doing so, at least use one of the others mentioned here. howsecureismypassword.net isn't very good.

edit: actually, it's terrible. For the password "passwords99", it has an estimate of 1 year! zxcvbn estimates that same password at 16 seconds, much better.

Checked with zxcvbn at https://dl.dropboxusercontent.com/u/209/zxcvbn/test/index.html

It's certainly very safe today but it might not be so safe in the future. According to Amph's link, that password would take about 100 million years to crack using a desktop PC. Moore's law states that processing power doubles every 18 months so after 35 years, we would have ((2050-2015)*12)/18 = 23 doublings. 100 million years halved 23 times is 11 years. Now imagine a supercomputer that is 1,000 times more powerful than a desktop PC and your password could then be cracked in days.

More characters is more secure
It's even better if you add both lower & both case, number, special character :)

But, make sure there aren't any malicious software when encrypt your wallet.dat
That software might know your password

It just needs to be strong not ridiculously long. The longer or more complex it is the more likely you'll forget it. Keeping your wallet safe and your over safety of your comp is most important. If you have a key logger it doesn't matter what your password is as they'll know it immediately.

The keylogger will only get your password if you type it in. It won't know it immediately when infected. If you are using the passphrase to create a password, you would definitely need a random password that is seriously random. You can try to recite it to yourself three times per day or write it down on somewhere safe. If you are encrypting wallet keys, password will only protect you in the event of someone gaining control of your PC.

Can the keylogger get my password if I copy-and-paste it (no typing)?

yes, you need to use the keyboard of your pc(virtual keyboard) or typing it in a way to camouflage it(for example, your password is "my name is", instead you write my.name.is, then you delete those two dot, using the mouse)

use zemna antikeylogger free, it help a lot

so even if i generate a password with a pass generator it can still be seen by keyloggers? what if you disconnect your pc from the net while setting a password? is that better?

You know there are mouse loggers, right?


It depends on how your keylogger does the job. Some keyloggers try to upload/share instantly which can be prevented if you are offline but some save the log and upload/share as soon as you connect to internet which can't be resolved without removing them. Most of the keyloggers are infected in pirated OS copies.

yeah but it doesn't change that a logger memorize every characters you type, in sequence...., so their password in that case would be the first plus two "back space" and two underline of the mouse, resulting in 14 characters in total, versus the original 10