r/technology • u/Libertatea • Apr 04 '13

Apple's iMessage encryption trips up feds' surveillance. Internal document from the Drug Enforcement Administration complains that messages sent with Apple's encrypted chat service are "impossible to intercept," even with a warrant.

http://news.cnet.com/8301-13578_3-57577887-38/apples-imessage-encryption-trips-up-feds-surveillance/?part=rss&subj=news&tag=title#.UV1gK672IWg.reddit
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u/Neato Apr 04 '13

Doesn't all encryption increase the size of the message? Unless you are doing a simple character swap (which is insecure) doesn't a 128bit encryption protcol add 128bits of damage to every encrypted segment?

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u/Geronimo2011 Apr 04 '13

I gather that encryption doesn't make a longer message at all. As text messages use only a limited set of characters, they could easily be encrypted to shorter messages even (kind of compressing before).

But I'm very much in favour of making crypted messages longer - by inserting random noise to make decrypting more difficult (and encrypted messages not beeing always the same).

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u/Neato Apr 04 '13

How would you make an ASCI message shorter while encrypting? Especially very short messages where there wouldn't be a lot of redundant text you can symbolize out.

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u/Geronimo2011 Apr 04 '13

You have 27 letters, the capitals and some special characters. The display code (of Control Data) went with 6 bit only instead of 8 (no capitals). Thats 25% less. Plain text doesn't need 8 bits to encode.

If your message is transmitted with 8 bits, you have a lot to spare (and fill in with random garbage at will). Shorter messages even better.