This stores its data in the same format as the existing KCT_TEXT, but
it displays differently in puttygen --dump, expecting that the data
will be full of horrible control characters, invalid UTF-8, etc.
The displayed data is of the form b64("..."), so you get a hint about
what the encoding is, and can still paste into Python by defining the
identifier 'b64' to be base64.b64decode or equivalent.
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