“So I agree, these are almost certainly decryption keys for something.”
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I’d say more likely they are hashes to verify if/when the big file is made available, those who download it can tell they got the real deal.
This is helpful in explaining what the posted numbers may mean:
http://emptylighthouse.com/what-are-numbers-wikileaks-keep-tweeting-john-kerry-ecuador-uk-fco-2086433286
But encryption keys is a very viable alternative theory. I think we’ll find out within a day or so.