Using arbitrary strings for keys in the params hash

Is there any way to construct a GET or POST request so that the
resulting params hash can incorporate arbitrary strings (i.e.
including ampersands, quotes, square brackets...) as its keys? I'm
trying to do something like

<form action="/translations/create" form="post">
<input type="text" name="translations[Hello]" value="Bonjour" />
<input type="text" name="translations[Press [OK] to continue]"
value="Touchez [OK] pour continuer" />
<input type="submit" />

to get back a params hash like

  "Press [OK] to continue"=>"Touchez [OK] pour continuer"

but the square brackets in the second field name cause it to be
omitted from the hash. I've tried escaping them with slashes, URL-
encoding and everything else I can think of, but it makes no

I guess one workaround would be to roll my own encoding scheme
(something like URL encoding but not quite...) and explicitly decode
the names at the other end, but it would be nice to be able to avoid
that step. Any suggestions?

Never mind... it occurred to me shortly after posting that I was being
needlessly 'cute' with the params hash there, and would be far better
off refactoring slightly:
<form action="/translations/create" form="post">
<input type="hidden" name="translations[0][original]" value="Hello" />
<input type="text" name="translations[0][translation]"
value="Bonjour" />
<input type="hidden" name="translations[1][original]" value="Press
[OK] to continue" />
<input type="text" name="translations[1][translation]" value="Touchez
[OK] pour continuer" />
<input type="submit" />

along with

@translations = {}
for entry in params[:translations]
  @translations[entry['original']] = entry['translation']