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Show HN: Forgiva – Never saves your passwords but regenerates them

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Re: Show HN: Forgiva – Never saves your passwords but regenerates them

#81

Post by marcusfrex »

tptacek wrote: post #79
marcusfrex wrote: post #77

Earlier quoted context omitted.

>> What does password complexity have to do with the strength of the algorithm used to generate passwords? It is not the algorithm only but if you can look a little bit more closely, it is iteration count too. It uses 1.000 times and 10.000 times more iterations respectively. Plus, depending on complexity, character set range enlarges. >> Why is this using PBKDF2? We would like to use more industry-standart way of th…

I don't think I asked the most important question clearly enough: Why do simpler passwords get a different construction? What does password complexity have to do with KDF hardness?

It's probably because different understanding of same terms. With "complexity" word we mean hardness to generate. It doesnt adds up more algorithms but character sets and hashing algorithms for PBKDF2 respectively.

Re: Show HN: Forgiva – Never saves your passwords but regenerates them

#83

Post by marcusfrex »

Canada wrote: post #66

How does this handle situations where the generated password isn't accepted by the site? eg. Is too long, absolutely must have at least one symbol and one number, etc. How does this handle changing passwords? How can I know from the master secret that xyz.com is on the 4th password?

>> How does this handle situations where the generated password isn't accepted by the site? eg. Is too long, absolutely must have at least one symbol and one number, etc.

You can specify password length if it gets too long and it's character set provides symbols, numbers and letters in it.

>> How does this handle changing passwords?

It has a renewal mechanism to switch to a new password.

>> How can I know from the master secret that xyz.com is on the 4th password?

Can you explain more about what you mean?

Re: Show HN: Forgiva – Never saves your passwords but regenerates them

#84

Post by marcusfrex »

KirinDave wrote: post #57

The Windows 64-bit installer is giving a bad signature even though its SHA256 installer hash appears to be correct. It looks like they used SHA1 checks in the installer. I suspect the author doesn't realize that older Win installers that use SHA1 are blindly rejected by Win10 as a security measure (mostly because it's so feasible to game). It is a very poor introduction to the application on the majority platform.

Actually installer compiled using Visual Studio 2015 on Windows 10 platform. Nothing specifically edited to the way of SHA1 but we fix it on next release.

>> It is a very poor introduction to the application on the majority platform.

Yes you are right it can be better and will be.

Re: Show HN: Forgiva – Never saves your passwords but regenerates them

#85

Post by marcusfrex »

RubyPinch wrote: post #33
icebraining wrote: post #26

Earlier quoted context omitted.

plus various hashing and encryption algorithms too. Is there any evidence that using multiple algorithms has any benefit over simply increasing the cost factor on one?

assuming combined correctly A( B( C(X) ) ), if A becomes broken in the future, its still B( C(X) ), as opposed to just revealing X straight away

Yes, definitely you are right.

And at the same time using various other methods "depending on the master key" makes it impossible for an accurate time and process estimation for brute-force attacks.

Re: Show HN: Forgiva – Never saves your passwords but regenerates them

#87

Post by tptacek »

marcusfrex wrote: post #81
tptacek wrote: post #79

Earlier quoted context omitted.

I don't think I asked the most important question clearly enough: Why do simpler passwords get a different construction? What does password complexity have to do with KDF hardness?

It's probably because different understanding of same terms. With "complexity" word we mean hardness to generate. It doesnt adds up more algorithms but character sets and hashing algorithms for PBKDF2 respectively.

Why, exactly, would a user ever want to generate a password with a weaker KDF?

A password with lower levels of string complexity might make sense --- 1Password's strong passwords can sometimes be rejected by crappy websites. A password that sacrifices cryptographic strength in order to save a few tens of milliseconds of KDF, though, makes no sense at all.

Also: really, you should not be using PBKDF2.

Re: Show HN: Forgiva – Never saves your passwords but regenerates them

#88

Post by tptacek »

marcusfrex wrote: post #78
tptacek wrote: post #60

Earlier quoted context omitted.

Not only did that not happen to bcrypt, but the whole point of bcrypt is that that doesn't happen: it's an adaptive hashing scheme, which means it comes with a dial you can turn to up the hardness as computers get faster. I would be nervous about taking password storage advice from someone who thinks bcrypt "got outdated and requires a better version". We had a Password Hashing Competition because people realized tha…

Probably i should explain what i meant with "got outdated and requires a better version" sentence. It is a race and as stronger algorithms comes to life -and stronger attack methods invented against them-, others gets simply weaker and weaker just like happened to MD2 and then MD4 And then MD5. Sorry for misunderstanding.

MD4 and MD5 didn't get easier and easier to crack due to cryptanalytic advances; it got easier to generate collisions. That's a serious problem for a cryptographic hash, but depending on the construction you're using, it might not have anything to do with MD5's suitability as a password hash. There's no password hash cracking tool I'm aware of that takes advantage of MD5's weaknesses.

So, no: this isn't happening with bcrypt.

Re: Show HN: Forgiva – Never saves your passwords but regenerates them

#89

Post by Scaevolus »

tptacek wrote: post #87
marcusfrex wrote: post #81

Earlier quoted context omitted.

It's probably because different understanding of same terms. With "complexity" word we mean hardness to generate. It doesnt adds up more algorithms but character sets and hashing algorithms for PBKDF2 respectively.

Why, exactly, would a user ever want to generate a password with a weaker KDF? A password with lower levels of string complexity might make sense --- 1Password's strong passwords can sometimes be rejected by crappy websites. A password that sacrifices cryptographic strength in order to save a few tens of milliseconds of KDF, though, makes no sense at all . Also: really, you should not be using PBKDF2.

I want a password manager with Argon2 configured to take 10 seconds and 1GB of RAM, playing a gratuitous 3D animation of a vault slowly opening alongside CPU and bandwidth utilization graphs.

Or if your attack model allows that reading protected files off a user's device is less likely than the cloud-synced database being compromised, you might derive the master encryption key as KDF_fast(KDF_slow(password)+password)), where KDF_slow takes 5 minutes and is stored on disk, but KDF_cheap takes 5 seconds.

Re: Show HN: Forgiva – Never saves your passwords but regenerates them

#90

Post by cauterized »

RubyPinch wrote: post #32
cauterized wrote: post #24

Earlier quoted context omitted.

What happens then if you want/need to rotate your password? How does it deal with stupid password format restrictions?

the salt gets changed so, either password database + master password gets stolen, or salt database + master password gets stolen

But then if the salt is stored and the algorithm is known, doesn't the salt just essentially become the password, from a security standpoint?
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