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Shameless plug time! Instead of remembering different passwords or using a password manager (and thus storing all your passwords somewhere) you can use https://salty.pw/

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Problem with this is when you need a password with a capital letter, or with no symbols, or only 8 characters long.

Additionally, how do you determine the service name? e.g. I have a wordpress.com account; do I call that 'WordPress' or 'wordpress' or 'wordpress.com'? I guess using the domain name is fairly robust, but then you get stuff like Stack Exchange, or the service changes its domain name, or international variants - google.com vs. google.co.uk.

Yup, arbitrary restrictions on passwords are a bane. I've thought about adding various modes but then you need to remember the mode you used. So far the most sensible option seems to be falling back to a password manager for those sites.

As for the service name I've had no issues with that in my use. Just come up with whatever rule is easy for you to remember. Worst case you'll have to make a few tries.

fantastic!

now a site has been breached and your username/password was leaked... yay, you'll have to either start using a traditional password manager for this special case or change every.single.password.you.have.

so useful ...not!

Or you could change the algorithm and make it unique to you. A bit more technical but the point isn't to be ultimately secure, just more secure than your 'neighbors'.

An interesting idea. Any thoughts on how to use this on websites that force a password change periodically? Using a versioned salt maybe, although that could get tricky after a few iterations.

Thats cool! Does it use simple concatenation or HMAC?

It's simple concatenation. The exact algorithm is described at the bottom of the page so that one could reproduce it (and their passwords) independently.

What about taking the 128 MSB vs 128 LSB, is there any research into how secure that is?

I vaguely remember giving it some consideration. But the bigger point is that my judgement on these things is not to be trusted since I'm just an application developer and not a crypto expert.

Yeah thats the thing, I'm not a crypto expert either but I'd love to use it. But if it gets popular, and there is an accidental mistake that actually makes it easy to guess passwords, I don't want to risk that happening.

Good news. Did a bit of investigation, it seems like this could be vulnerable to a length extension attack [1] (though the attack its still pretty useless in this particular case) but it appears that truncating is both safe and takes care of length extension attacks! [2]

[1]: https://en.wikipedia.org/wiki/Length_extension_attack

[2]: https://crypto.stackexchange.com/questions/18606/is-xoring-a...

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