Dr Stephen Henson <lists(_at_)drh-consultancy(_dot_)demon(_dot_)co(_dot_)uk>
writes:
Some implementations (by accident or design) restrict e to 32 bits in size.
This is actually quite useful, although the limitation in the most widespread
implementation that does this is more or less arbitrary (when they designed
their key blob format they only left 32 bits for e) it's conveniently
discouraged anyone from using large e values (well, almost anyone anyway, I
once ran into an implementation from Germany that used a 32-bit e, but also
encoded it incorrectly so anything over INT_MAX ended up negative), so it's
fairly safe to require |e| to be < 32 bits for DoS-protection purposes.
Peter.