Search box must contain at least three letters - how to convey?

Question

We have a system that searches user names. Since the names are encrypted (getting this working was tricky on the back end too), we can't accept an empty search or one with one letter, since that would start decrypting too many names.

We've been thinking about how to convey to the user that they've got to input a minimum number of letters, and nothing obvious is jumping out at us. Some ideas:

• We could gray out the search button until we get the minimum. The obvious drawback is that people might well think the search feature is somehow not active at all.
• We could warn people after the fact "sorry, you need to type at least 3 letters to search", but that's kind of annoying. Probably the best solution so far though, since most people will likely search on an actual name.
• More work on the backend might be able fix things, but searching and sorting encrypted data is "not easy", and might not be a good compromise, since there are plenty of other things that need doing with the system too.

Answer 1

I think the best solution is probably also the simplest: telling the user about the restriction.

[________] Type at least 3 characters

Optionally, after the 3 characters have been input you can hide, grey out the restriction message or place a tick next to it.

Answer 2

why don't u try something like here on stack exchange? , while commenting it shows "14 more to go....."

So why cant you display in same way? onkey press just show them 3 more to go or start count down for each character... hope this is a clean approach!