On: 86% of CrashCrate subscribers used passwords already leaked in other breaches

[saimiam]

I do this but I'd love to have someone tell me why this is a terrible idea (apart from the obvious one of using a 3rd party sha256 calculator)

1. Have a very short prefix and a suffix I can expect to remember 2. Password for every website gets generated like this <prefix> + website name + <suffix> 3. Generate SHA256 hash of #2 4. Use #3 as password for the site. 5. Save password to password manager

Pros - 1. losing a password on one site doesn't compromise the pattern on others because cracking sha256 is still not possible (afaik) 2. relatively easy rules to create new password 3. If I HAVE to login on a computer without my password manager (e.g., public workstation), I can regenerate my password on the fly.

Cons - 1. I use an external sha-256 calculator 2. Some sites enforce password length and arbitrary case/symbols rules. Have to manipulate generated password by hand

[pryce → saimiam]

1. This relies on a mistaken expectation that all sites you use being able to accept SHA256 output - presumably in Base64 or similar- as an acceptable password. You will likely have to compromise this.

2. You have no credential expiry built into this approach. Even should you decide to not use credential expiry, if one site demands it, your strategy doesn't work.

3. You are still at risk of having your passwords leak because: Anyone who compromises a public machine on which you generated your password manually (eg leaving any traces in logs, bash history etc) who eyeballs your SHA256 input prefix_ashleymadison.com_suffix , now has very clear reasons to expect they can generate passwords based on prefix_facebook.com_suffix and pre_barclaysbank.com_suffix because your credentials between sites are now not independent of each other, and worse, directly suggest each other.

Ignoring keyloggers and bash history issues etc any simple 'over the shoulder' attacker, likewise, get a pretty good guess at all of your passwords all at once by observing you generate a password for one site just once.

In short, if you attempt to use an approach like this, you no longer just have to protect your password, you have to absolutely protect the knowledge of the algorithm by which you generate your password for different sites. This being compromised just once potentially compromises all your passwords, substantially widening the ways in which you can be harmed.

[saimiam → pryce]

> credential expiry

Good point. I'll have to add something to prefix of prefix/suffix for sites which remember previous passwords (or hashes).

> leaving any traces in logs

This I will have to resolve by localizing my sha256 generation process.

> over the shoulder

Also a good point.

Thank you for thinking this through for me. Appreciate it.

[stevekemp → saimiam]

At some point a site you use will be compromised, so you have a problem as that site will require a new password.

So your login routine is now:

* Generate your password via hash(prefix + sitename + suffix), and use it on every site, except that compromised one. Because it invalidated your old password and won't let you reuse it.

In short you have a versioning problem. And you have to remember it. The problem compounds for each site you use which insists upon a change for whatever reason.

(Also your own "con" - different sites have different restrictions/caveats for password formats.)

Use a password-manager, it really is the best way to have a unique and secure password for each site.

[saimiam → stevekemp]

> use a pw manager

I do use my Mac's Keychain Access. My issue started when I had to use a work computer for logging into a newspaper account and I couldn't remember what it was because it was saved on my personal laptop. That's when I came up with this scheme.

> versioning problem

Someone else pointed this out as well. Thanks for thinking this thru.