I found this very strange The permitted characters and length for passwords are defined as a regular expression in Evernote’s API, but spaces are left out, Evernote says, because leading and trailing spaces presents a problem. “Software needs to precisely determine how to treat leading and trailing spaces,” Dave Engberg, Evernote’s CTO, told Ars. “Some UI frameworks and third-party applications would unreliably trim…
Additionally. "Adding support for spaces only in the middle of the password would make the regular expression defining them three times longer, Engberg said." So they admit they already have the regex definition that would allow this, but for some reason don't want to put it in production? How strange.
Sounds like he's thinking his regex is of their allowed "set" of [A-Za-z0-9!@#$%^&*()_.-], and thinks that to support space but not at start or end, he'd need ^[set][ set]{6,}[set]$, repeating his set 3 times except with a space added to the middle set. That's not accurate. He can add a space to his set, then put a not-space assertion at the start and end, like ^(?! )[ set]{8,}(?<! )$ and call it a day. (And perhaps \A and \Z instead of ^ and $ depending on what he does with new lines.)