[tor-bugs] #11611 [Obfsproxy]: obfs2/obfs3 AES counter initialization is incorrect.

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#11611: obfs2/obfs3 AES counter initialization is incorrect.
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     Reporter:  yawning    |      Owner:  asn
         Type:  defect     |     Status:  new
     Priority:  normal     |  Milestone:
    Component:  Obfsproxy  |    Version:
   Resolution:             |   Keywords:
Actual Points:             |  Parent ID:
       Points:             |
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Comment (by asn):

 Please see branch `bug11611` in my repo:
 https://gitweb.torproject.org/user/asn/obfsproxy.git/commitdiff/7b562f53fb02f930b3c43f1571a90f6634df0664

 As I understand it, the counter will now overlfow after 2^128^ block
 encryptions. This sounds unlikely to ever happen, but because I don't like
 this behavior I disabled it by default. obfs2 and obfs3 explicitly enable
 the wraparound behavior. Future protocols should consider using an initial
 counter value of 0 :/

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/11611#comment:3>
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