[tor-bugs] #5406 [Tor Relay]: Use EVP_aes_128_ctr() on OpenSSL >= 1.0.1

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#5406: Use EVP_aes_128_ctr() on OpenSSL >= 1.0.1
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 Reporter:  nickm        |          Owner:                    
     Type:  enhancement  |         Status:  new               
 Priority:  normal       |      Milestone:  Tor: 0.2.3.x-final
Component:  Tor Relay    |        Version:                    
 Keywords:               |         Parent:                    
   Points:               |   Actualpoints:                    
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 Starting with OpenSSL 1.0.1, there is an EVP value to provide counter-mode
 AES. We definitely want to be using this one for our counter mode
 implementation in aes.c, since it appears to automatically use the best
 available AES implementation, including tricky ones that use
 AESNI/bitsliced/vectorized implementations.

 Bitsliced and vectorized implementations of counter mode are not only
 faster than the straightforward assembly versions, but also run in
 constant-time.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/5406>
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