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  6. <title>VeraCrypt - Free Open source disk encryption with strong security for the Paranoid</title>
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  7. <meta name="description" content="VeraCrypt is free open-source disk encryption software for Windows, Mac OS X and Linux. In case an attacker forces you to reveal the password, VeraCrypt provides plausible deniability. In contrast to file encryption, data encryption performed by VeraCrypt is real-time (on-the-fly), automatic, transparent, needs very little memory, and does not involve temporary unencrypted files."/>
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  32. <a href="Hardware%20Acceleration.html">Hardware Acceleration</a>
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  35. <div class="wikidoc">
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  36. <h1>Hardware Acceleration</h1>
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  37. <div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
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  38. Some processors (CPUs) support hardware-accelerated <a href="AES.html" style="text-align:left; color:#0080c0; text-decoration:none.html">
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  39. AES</a> encryption,* which is typically 4-8 times faster than encryption performed by the purely software implementation on the same processors.</div>
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  40. <div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
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  41. By default, VeraCrypt uses hardware-accelerated AES on computers that have a processor where the Intel AES-NI instructions are available. Specifically, VeraCrypt uses the AES-NI instructions that perform so-called AES rounds (i.e. the main portions of the AES
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  42.  algorithm).** VeraCrypt does not use any of the AES-NI instructions that perform key generation.</div>
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  43. <div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
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  44. Note: By default, VeraCrypt uses hardware-accelerated AES also when an encrypted Windows system is booting or resuming from hibernation (provided that the processor supports the Intel AES-NI instructions).</div>
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  45. <div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
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  46. To find out whether VeraCrypt can use hardware-accelerated AES on your computer, select
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  47. <em style="text-align:left">Settings</em> &gt; <em style="text-align:left">Performance/</em><em>Driver Configuration</em> and check the field labeled '<em style="text-align:left">Processor (CPU) in this computer supports hardware acceleration for AES</em>'.</div>
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  48. <div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
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  49. To find out whether a processor you want to purchase supports the Intel AES-NI instructions (also called &quot;AES New Instructions&quot;), which VeraCrypt uses for hardware-accelerated AES, please check the documentation for the processor or contact the vendor/manufacturer.
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  50.  Alternatively, click <a href="http://ark.intel.com/search/advanced/?AESTech=true" style="text-align:left; color:#0080c0; text-decoration:none">
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  51. here</a> to view an official list of Intel processors that support the AES-NI instructions. However, note that some Intel processors, which the Intel website lists as AES-NI-supporting, actually support the AES-NI instructions only with a Processor Configuration
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  52.  update (for example, i7-2630/2635QM, i7-2670/2675QM, i5-2430/2435M, i5-2410/2415M). In such cases, you should contact the manufacturer of the motherboard/computer for a BIOS update that includes the latest Processor Configuration update for the processor.</div>
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  53. <div style="text-align:left; margin-top:19px; margin-bottom:19px; padding-top:0px; padding-bottom:0px">
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  54. If you want to disable hardware acceleration of AES (e.g. because you want VeraCrypt to use only a fully open-source implementation of AES), you can do so by selecting<em style="text-align:left"> Settings</em> &gt;
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  55. <em style="text-align:left">Performance and Driver Options </em>and disabling the option '<em style="text-align:left">Accelerate AES encryption/decryption by using the AES instructions of the processor</em>'. Note that when this setting is changed, the operating
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  56.  system needs to be restarted to ensure that all VeraCrypt components internally perform the requested change of mode. Also note that when you create a VeraCrypt Rescue Disk, the state of this option is written to the Rescue Disk and used whenever you boot
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  57.  from it (affecting the pre-boot and initial boot phase). To create a new VeraCrypt Rescue Disk, select
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  58. <em style="text-align:left">System</em> &gt; <em style="text-align:left">Create Rescue Disk</em>.</div>
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  59. <p>&nbsp;</p>
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  60. <hr align="left" size="1" width="189" style="text-align:left; height:0px; border-width:0px 1px 1px; border-style:solid; border-color:#000000">
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  61. <p><span style="text-align:left; font-size:10px; line-height:12px">* In this chapter, the word 'encryption' also refers to decryption.</span><br style="text-align:left">
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  62. <span style="text-align:left; font-size:10px; line-height:12px">** Those instructions are
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  63. <em style="text-align:left">AESENC</em>, <em style="text-align:left">AESENCLAST</em>,
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  64. <em style="text-align:left">AESDEC</em>, and <em style="text-align:left">AESDECLAST</em> and they perform the following AES transformations:
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  65. <em style="text-align:left">ShiftRows</em>, <em style="text-align:left">SubBytes</em>,
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  66. <em style="text-align:left">MixColumns</em>, <em style="text-align:left">InvShiftRows</em>,
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  67. <em style="text-align:left">InvSubBytes</em>, <em style="text-align:left">InvMixColumns</em>, and
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  68. <em style="text-align:left">AddRoundKey</em> (for more details about these transformations, see [3])</span><span style="text-align:left; font-size:10px; line-height:12px">.</span></p>
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