To regenerate your passwords, an adversary would need both to figure out your algorithm and obtain your piece of paper.
Personally, I have different mp for different “security domains” (google/fb, banks, other socials, ...), and I’m using just a sha256 plus encoding — a trade off between requiring a stronger mp, and being able to easily remember everything, including the algorithm.
I wrote more about it here: https://hackernoon.com/mempa-a-modern-deterministic-password...
"Password Strength" https://www.xkcd.com/936/
Diceware: http://world.std.com/%7Ereinhold/diceware.html "This page offers a better way to create a strong, yet easy to remember passphrase for use with encryption and security programs. Weak passwords and passphrases are one of the most common flaws in computer security. Take a few minutes and learn how to do it right."
I currently have about ~15 different passwords I use. I know which to use based on how long I've been using the service. Why is this strategy ineffective?? At most a hacker could get 3-4 of the services I use, and even then they'd need to find each of those services out of the hundreds I use. I also have 4 different emails I use for logins.
The problem with using the same password on multiple sites is this: if any one site gets pwnd, it gets a lot easier for the cybercreeps to pwn your account on other sites (says Obvious Man).
It doesn't take much technical skill to credential-stuff--to hammer a lot of sites with a list of credentials. So, keeping the list of sites you actually use a secret is not effective.
This whole deal sucks. But it's real.
As for the password strategy, I imagine you could be vulnerable if any two important accounts - say, email and bank - both used the same password. Are you confident this is not the case?
I assume certain emails associate with certain types of accounts, which could flaw your strategy. If you're able to remember ~15 different passwords with random emails, congrats on your stellar memory!
Either use a service that syncs up to a server, or a standalone apps and save its encrypted database to a shared filesystem such as Dropbox or pcloud.
I suspect most people will end up having weak algorithms the same way they have weak passwords.
https://penguindreams.org/blog/password-algorithms/
I felt like they could bridge the gap between a regular person who is weary of having to look up every password using a password manager (although a lot of them make it easier with browser plugins and phone apps, but it's still an extra step).
However, in light of the recent Gentoo vandalism, it seems like a user had their password formula figured out. Algorithms do guard against credential stuffing; that particular person was most likely specifically attacked. If you have a strong formula, it should take at least 7 or 8 passwords to begin to figure it out.
At a minimum, if you have non-tech friends who use a single password for everything, start them off easy: You should use a manager. It's the only way to guard everything. But if they don't want to go that route, at a bare minimum, recommend that they need three passwords. One that's highly secure for banks, employment and government. One insecure for everything else. And finally one for your e-mail which should be shared with nothing!
Password algorithms are a step up. It's a trade off of course: you are protected against credential stuffing and you don't need a manager; you can have a different password for every site without having to memorize a hundred password; only the exceptions to stupid password rules. The trade off: your algorithm probably sucks and if you're targeted specifically, someone can get to everything.
Every aspect of security involves trade offs. The various password management choices, along with their advantages and disadvantages, should be taught in high school.