> One implies the other. You turn echo off. Then you write asterisks.

That's not how it works. Sudo turns off echo but otherwise keeps the terminal in it's normal cooked canonocal mode, meaning sudo only sees what you've entered after you hit enter. To print asteriks as you type requires putting the terminal in raw mode, which has the addition consequence of needing to implement shit like backspace yourself. Still a UX win worth doing, but it's pretty clear that skipping that and just disabling echo is an easier lazier implementation.

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themafia 11 hours ago | parent [-]

You're correct, but, the echo and canonical mode flags are literally in the same termios structure member. One is no more complicated to change than the other. You can also easily switch to character at a time read() which makes handling backspace, erase or kill exceedingly simple.

I still doubt the claim the scheme employed by sudo was done because it "was easier."

	▲	mikkupikku 5 hours ago \| parent [-]
		The first is like 3 lines of code, to get the attrs, disable the echo flag then set the attrs again. The second is.. I don't know probably about twenty lines of code to handle the primitive line editing yourself and also asterisk printing. In my view, this is enough of a difference to motivate a conclusion that the first is good enough. Also note that this decision was made back in the early 70s when login was first implemented, and it established a convention which was very easy and convienent to carry forward to su and later sudo.