Java JCE providers - what does "clean room implementation" mean?

I'm required to write a JCE provider. I have learned that I need to use the bouncy cast开发者_如何学Cle clean room implementation. Could you please tell me what "clean room implementation" means in in this context?

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Clean room implementation means in this context that the code was written only from the description and specification, but not with access to any potentially troublesome code.

This is important as the Sun source code previously was under a license which was incompatible with especially GPL distributions. By ensuring that the code was not written without any access to such code, it is guaranteed that the Sun license could not later be found to apply to the clean room implementation, and then again be incompatible with the GPL license or any other restrictions.

In other words, it is a guarantee that the license shown will hold.

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Despite the name, most re-implementations are done in rooms with mostly empty beer cans and pizza boxes. This is speaking from past experience, you understand :-)

However, in the context of chip development, a clean room is one where small imperfections (like dust) can cause serious problems at the nano scale. So they're kept incredibly clean, with air scrubbers, protective suits (protecting the environment, notvthe wearer) etc.

By analogy, software clean room development is done without any access to imperfections that could cause problems. In the case of open-source software, this means not having access to an implementation that might be "tainted" by an incompatible license. (It's not just GPL, but this is commonly cited due to its viral nature). However, this also applies to closed source reverse engineering projects, like the creation of the IBM compatible BIOS that opened the market to IBM clones back in the 80's.