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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">What OpenSSL does is not necessarily obvious. The INSTALL document talks about the no-asm configuration option. Details about what the assembler
code does in terms of optimization are only available by reading the source code comments in the various Perl files that generate the assembler, mostly.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">On x86, the assembly code uses the CPUID instruction (see the OPENSSL_ia32cap.pod manpage) to determine if various instructions (AES, SSE, MMX, etc)
are available and will use them if so. For other processors, similar tests are performed if at all possible.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">I have added this to the FAQ<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">--
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">Senior Architect, Akamai Technologies<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">Member, OpenSSL Dev Team<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">IM: richsalz@jabber.at Twitter: RichSalz<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> - JinsongJi [mailto:jjsbear@hotmail.com]
<br>
<b>Sent:</b> Wednesday, August 09, 2017 9:09 AM<br>
<b>To:</b> openssl-users@openssl.org<br>
<b>Subject:</b> [openssl-users] Does openssl pick low level interface or high level interface to do encrypt?<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Calibri",sans-serif;color:black">Hi,<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Calibri",sans-serif;color:black"> <o:p></o:p></span></p>
<pre style="margin-bottom:15.0pt;background-image:initial;background-attachment:initial;background-size: initial;background-origin: initial;background-clip: initial;background-"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:black">For one simple operation: </span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#778596">openssl enc -aes-256-cbc -salt -in foo.txt -out foo.enc</span><span style="color:black"><o:p></o:p></span></pre>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Calibri",sans-serif;color:black">Does openssl pick classic implementation or AES-NI implementation to do this encrypt?
<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Calibri",sans-serif;color:black"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Calibri",sans-serif;color:black">Does any user/application always pick classic implementation for AES operation regardless of AES-NI improves speed much?<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Calibri",sans-serif;color:black">Is there any document about this interface selection?<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Calibri",sans-serif;color:black"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:"Calibri",sans-serif;color:black">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:black">Jinsong</span><span style="font-family:"Calibri",sans-serif;color:black">
<o:p></o:p></span></p>
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