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  12   <h1>The rEFInd Boot Manager:<br />Managing Secure Boot</h1>
  13
  14   <p class="subhead">by Roderick W. Smith, <a
  15 href="mailto:rodsmith@rodsbooks.com">rodsmith@rodsbooks.com</a></p>
  16
  17 <p>Originally written: 11/13/2012; last Web page update:
  18 4/25/2013, referencing rEFInd 0.6.9</p>
  19
  20
  21 <p>I'm a technical writer and consultant specializing in Linux technologies. This Web page is provided free of charge and with no annoying outside ads; however, I did take time to prepare it, and Web hosting does cost money. If you find this Web page useful, please consider making a small donation to help keep this site up and running. Thanks!</p>
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 125 <hr />
 126
 127 <p>This page is part of the documentation for the rEFInd boot manager. If a Web search has brought you here, you may want to start at the <a href="index.html">main page.</a></p>
 128
 129 <hr />
 130
 131 <p class="sidebar"><b>Note:</b> My <a href="http://www.rodsbooks.com/efi-bootloaders/">Managing EFI Boot Loaders for Linux</a> Web page includes a much more detailed description of Secure Boot in its <a href="http://www.rodsbooks.com/efi-bootloaders/secureboot.html">Dealing with Secure Boot</a> sub-page. You should consult this page if you want to disable Secure Boot, generate your own keys, or perform other such tasks.</p>
 132
 133 <div class="navbar">
 134
 135 <h4 class="tight">Contents</h4>
 136
 137 <ul>
 138
 139 <li class="tight"><a href="#basic">Basic Issues</li>
 140
 141 <li class="tight"><a href="#installation">Installation Issues</a></li>
 142
 143 <li class="tight"><a href="#mok">Managing Your MOKs</a></li>
 144
 145 <li class="tight"><a href="#caveats">Secure Boot Caveats</a></li>
 146
 147 </ul>
 148
 149 </div>
 150
 151 <p>If you're using a computer that supports Secure Boot, you may run into extra complications. This feature is intended to make it difficult for malware to insert itself early into the computer's boot process. Unfortunately, it also complicates multi-boot configurations such as those that rEFInd is intended to manage. This page describes some <a href="#basic">secure boot basics</a> and two specific aspects of rEFInd and its interactions with Secure Boot: <a href="#installation">installation issues</a> and <a href="#mok">MOK management.</a> It concludes with a look at <a href="#caveats">known bugs and limitations</a> in rEFInd's Secure Boot features.</p>
 152
 153 <a name="basic">
 154 <h2>Basic Issues</h2>
 155 </a>
 156
 157 <p class="sidebar"><b>Note:</b> You don't <i>have to</i> use Secure Boot.
 158 If you don't want it, you can <a
 159 href="http://www.rodsbooks.com/efi-bootloaders/secureboot.html#disable">disable
 160 it,</a> at least on <i>x</i>86-64 PCs. If an ARM-based computer ships with
 161 Windows 8, this isn't an option for it. Unfortunately, the shim software
 162 described on this page currently supports only <i>x</i>86-64, not
 163 <i>x</i>86 or ARM.</p>
 164
 165 <p>Through 2012, it became obvious that Secure Boot would be a feature that was controlled, to a large extent, by Microsoft. This is because Microsoft requires that non-server computers that display Windows 8 logos ship with Secure Boot enabled. As a practical matter, this also means that such computers ship with Microsoft's keys in their firmware. In the absence of an industry-standard body to manage the signing of Secure Boot keys, this means that Microsoft's key is the only one that's more-or-less guaranteed to be installed on the computer, thus blocking the ability to boot any OS that lacks a boot path through Microsoft's signing key.</p>
 166
 167 <p class="sidebar"><b>Note:</b> The <a href="http://www.linuxfoundation.org">Linux Foundation</a> has released a signed version of their <a href="http://blog.hansenpartnership.com/linux-foundation-secure-boot-system-released/">PreBootloader,</a> which functions something like shim; however, where shim requires signing all binaries that don't already have valid Secure Boot keys and managing a small number of keys, PreBootloader requires registering every authorized binary. I haven't had the chance to revise this documentation to cover PreBootloader, but you may want to use it instead of shim if you want to manage a small number of binaries that are not already signed with a Secure Boot key, MOK, or a key built into a signed version of shim.</p>
 168
 169 <p>Fortunately, Microsoft will sign third-party binaries with their key&mdash;or more precisely, with a key that Microsoft uses to sign third-party binaries. (Microsoft uses another key to sign its own binaries, and some devices, such as the Microsoft Surface tablet, lack the third-party Microsoft key.) A payment of $99 to Verisign enables a software distributor to sign as many binaries as desired. Red Hat (Fedora), Novell (SUSE), and Canonical (Ubuntu) have all announced plans to take advantage of this system. Unfortunately, using a third-party signing service is an awkward solution for open source software. In fact, for this very reason Red Hat has developed a program that it calls <i>shim</i> that essentially shifts the Secure Boot "train" from Microsoft's proprietary "track" to one that's more friendly to open source authors. Shim is signed by Microsoft and redirects the boot process to another boot loader that can be signed with keys that the distribution maintains and that are built into shim. Fedora 18 also uses this system. SUSE has announced that it will use the same system, as does Ubuntu with version 12.10 and later. SUSE has contributed to the shim approach by providing expansions to shim that support a set of keys that users can maintain themselves. These keys are known as Machine Owner Keys (MOKs), and managing them is described later, in <a href="#mok">Managing MOKs.</a> To reiterate, then, there are potentially three ways to sign a binary that will get it launched on a computer that uses shim:</p>
 170
 171 <ul>
 172
 173 <li><b>Secure Boot keys</b>&mdash;These keys are managed by the EFI
 174     firmware. In a default configuration, Microsoft is the only party
 175     that's more-or-less guaranteed to be able to sign boot loaders with
 176     these keys; however, it's possible to <a
 177     href="http://www.rodsbooks.com/efi-bootloaders/secureboot.html#add_keys">replace
 178     Microsoft's keys with your own,</a> in order to take full control of
 179     Secure Boot on your computer. The trouble is that this process is
 180     tedious and varies in details from one computer to another.</li>
 181
 182 <li><b>Shim's built-in keys</b>&mdash;It's possible, but not necessary, to
 183     compile shim with a built-in public key. Its private counterpart can
 184     then be used to sign binaries. In practice, this key type is limited in
 185     utility; it's likely to be used by distribution maintainers to sign
 186     their own version of GRUB and the Linux kernels that it launches,
 187     nothing more. On the plus side, shim's keys require little or no
 188     maintenance by users. One potential complication is that if you swap
 189     out one shim binary for another, its built-in key may change, which
 190     means that the replacement shim might no longer launch its follow-on
 191     boot loader.</li>
 192
 193 <li><b>MOKs</b>&mdash;Versions 0.2 and later of shim support MOKs, which
 194     give you the ability to add your own keys to the computer. If you want
 195     to install multiple Linux distributions in Secure Boot mode, MOKs are
 196     likely to be helpful. They're vital if you want to launch kernels you
 197     compile yourself or use boot managers or boot loaders other than those
 198     provided by your distribution.</li>
 199
 200 </ul>
 201
 202 <p>All three key types are the same in form&mdash;shim's built-in keys and MOKs are both generated using the same tools used to generate Secure Boot keys. The keys can be generated with the common <tt>openssl</tt> program, but signing EFI binaries requires a rarer program called <tt>sbsign</tt> or <tt>pesign</tt>. Although it's theoretically possible to use rEFInd without signing your own binaries, this is not yet practical, because distributions don't yet provide their own signed binaries or the public MOK files you must have to enroll their keys. With any luck this will change in 2013. At the very least, many distributions will begin supporting Secure Boot in the near future, and with any luck they'll include their public MOKs for use with other distributions' versions of shim.</p>
 203
 204 <p>Because shim and MOK are being supported by several of the major players in the Linux world, I've decided to do the same with rEFInd. Beginning with version 0.5.0, rEFInd can communicate with the shim system to authenticate boot loaders. If a boot loader has been signed by a valid UEFI Secure Boot key, a valid shim key, or a valid MOK key, rEFInd will launch it. rEFInd will also launch unsigned boot loaders or those with invalid signatures <i>if</i> Secure Boot is disabled in or unsupported by the firmware. (If that's your situation, you needn't bother reading this page.)</p>
 205
 206 <p>Version 0.5.0 ships signed with my own keys, and I provide the public version of this key with the rEFInd package. This can help simplify setup, since you needn't generate your own keys to get rEFInd working; however, without public keys for the boot loaders that rEFInd launches, you'll still need to generate keys and sign your boot loaders, as described in the <a href="#mok">Managing Your MOKs</a> section.</p>
 207
 208 <a name="installation">
 209 <h2>Installation Issues</h2>
 210 </a>
 211
 212 <p>A working Secure Boot installation of rEFInd involves at least three programs, and probably four or more, each of which must be installed in a specific way:</p>
 213
 214 <ul>
 215
 216 <li><b>shim</b>&mdash;You can download a version of shim signed with Microsoft's Secure Boot key <a href="http://www.codon.org.uk/~mjg59/shim-signed/">here.</a> This version (created by shim's developer, former Red Hat employee Matthew J. Garrett) includes a shim key that's used by nothing but the <tt>MokManager.efi</tt> program that also ships with the program. Thus, to use this version of shim, you must use MOKs. Fedora 18's version of shim includes its own key but can also use MOKs; but to use it with rEFInd, you must still enroll rEFInd's MOK. Ubuntu 12.10 ships with its own shim, but that version doesn't support MOKs and so is useless for launching rEFInd. Future versions of SUSE and probably other distributions will come with their own variants of shim, most of which will no doubt support their own shim keys as well as MOKs. You should install shim just as you would install other EFI boot loaders, as described <a href="http://www.rodsbooks.com/efi-bootloaders/installation.html">here.</a> For use in launching rEFInd, it makes sense to install <tt>shim.efi</tt> in <tt>EFI/refind</tt> on your ESP, although of course this detail is up to you.</li>
 217
 218 <li><b>MokManager</b>&mdash;This program is included with shim 0.2 and later. It presents a crude user interface for managing MOKs, and it's launched by shim if shim can't find its default boot loader (generally <tt>grubx64.efi</tt>) or if that program isn't properly signed. In principle, this program could be signed with a Secure Boot key or a MOK, but the binary in Garrett's shim 0.2 is signed with a shim key, and I expect that versions distributed with most Linux distributions will also be signed by their respective shim keys. This program should reside in the same directory as <tt>shim.efi</tt>, under the name <tt>MokManager.efi</tt>. Although you could theoretically do without MokManager, in practice you'll need it at least temporarily to install the MOK with which rEFInd is signed.</li>
 219
 220 <li><b>rEFInd</b>&mdash;Naturally, you need rEFInd. Because shim is hard-coded to launch a program called <tt>grubx64.efi</tt>, you must install rEFInd using that name and to the same directory in which <tt>shim.efi</tt> resides. In theory, rEFInd could be signed with a Secure Boot key, a shim key, or a MOK; however, because Microsoft won't sign binaries distributed under the GPLv3, I can't distribute a version of rEFInd signed with Microsoft's Secure Boot key; and as I don't have access to the private shim keys used by any distribution, I can't distribute a rEFInd binary signed by them. (If distributions begin including rEFInd in their package sets, though, such distribution-provided binaries could be signed with the distributions' shim keys.) Thus, rEFInd will normally be signed by a MOK. Beginning with version 0.5.0, rEFInd binaries that I provide are signed by me. Beginning with version 0.5.1, the installation script provides an option to sign the rEFInd binary with your own key, provided the necessary support software is installed.</li>
 221
 222 <li><b>Your boot loaders and kernels</b>&mdash;Your OS boot loaders, and perhaps your Linux kernels, must be signed. They can be signed with any of the three key types. Indeed, your system may have a mix of all three types&mdash;a Windows 8 boot loader will most likely be signed with Microsoft's Secure Boot key, GRUB and kernels provided by most distributions will be signed with their own shim keys, and if you use your own locally-compiled kernel or a boot loader from an unusual source you may need to sign it with a MOK. Aside from signing, these files can be installed in exactly the same way as if your computer were not using Secure Boot.</li>
 223
 224 </ul>
 225
 226 <p>Because of variables such as which version of shim you're using and whether you're installing a pre-signed version of rEFInd or want to sign it yourself, I can't provide an absolutely complete procedure for installing rEFInd to work with Secure Boot. Broadly speaking, though, the procedure should be something like this:</p>
 227
 228 <ol>
 229
 230 <li>Boot the computer. This can be a challenge in and of itself. You may
 231     need to use a Secure Boot&ndash;enabled Linux emergency disc,
 232     temporarily disable Secure Boot, or do the work from Windows.</li>
 233
 234 <li><a href="getting.html">Download rEFInd</a> in binary form (the binary
 235     zip or CD-R image file). If you download the binary zip file, unzip it;
 236     if you get the CD-R image file, burn it to a CD-R and mount it.</li>
 237
 238 <li>Download shim from <a
 239     href="http://www.codon.org.uk/~mjg59/shim-signed/">Matthew J. Garrett's
 240     download site</a> or from your distribution. (Don't use Ubuntu 12.10's
 241     version, though; as noted earlier, it's inadequate for use with
 242     rEFInd.) Fedora 18 ships with a signed shim, but I've not yet tested
 243     it.</li>
 244
 245 <p class="sidebar"><b>Tip:</b> If you're running Linux, you can save some effort by using the <tt>install.sh</tt> script with its <tt>--shim <tt class="variable">/path/to/shim.efi</tt></tt> option rather than installing manually, as in steps 4&ndash;6 of this procedure. If you've installed <tt>openssl</tt> and <tt>sbsign</tt>, using <tt>--localkeys</tt> will generate local signing keys and re-sign the rEFInd binaries with your own key, too. You can then use <tt>sbsign</tt> and the keys in <tt>/etc/refind.d/keys</tt> to sign your kernels or boot loaders.</p>
 246
 247 <li>Copy the <tt>shim.efi</tt> and <tt>MokManager.efi</tt> binaries to the
 248     directory you intend to use for rEFInd&mdash;for instance,
 249     <tt>EFI/refind</tt> on the ESP.</li>
 250
 251 <li>Follow the installation instructions for rEFInd on the <a
 252     href="installing.html">Installing rEFInd</a> page; however, give rEFInd
 253     the filename <tt>grubx64.efi</tt> and register <tt>shim.efi</tt> with
 254     the EFI by using <tt>efibootmgr</tt> in Linux or <tt>bcdedit</tt> in
 255     Windows. Be sure that rEFInd (as <tt>grubx64.efi</tt>),
 256     <tt>shim.efi</tt>, and <tt>MokManager.efi</tt> all reside in the same
 257     directory.</li>
 258
 259 <li>Copy the <tt>refind.cer</tt> file from the rEFInd package to your ESP,
 260     ideally to a location with few other files. (The rEFInd installation
 261     directory should work fine.)</li>
 262
 263 <li>Reboot. With any luck, you'll see a simple text-mode user interface
 264     with a label of <tt>Shim UEFI key management</tt>. This is the
 265     MokManager program, which shim launched when rEFInd failed verification
 266     because its key is not yet enrolled.</li>
 267
 268 <li>Press your down arrow key and press Enter to select <tt>Enroll key from
 269     disk</tt>. The screen will clear and prompt you to select a key, as
 270     shown here:</li>
 271
 272     <br /><IMG SRC="MokManager1.png" ALIGN="CENTER" WIDTH="676"
 273     HEIGHT="186" ALT="MokManager's user interface is crude but effective."
 274     BORDER=2> <br />
 275
 276 <li>Each of the lines with a long awkward string represents a disk
 277     partition. Select one and you'll see a list of files. Continue
 278     selecting subdirectories until you find the <tt>refind.cer</tt> file
 279     you copied to the ESP earlier. (Note that the long lines can wrap
 280     and hide valid entries on the next line, so you may need to select
 281     a disk whose entry is masked by another one!)</li>
 282
 283 <li>Select <tt>refind.cer</tt>. You can type <tt class="userinput">1</tt>
 284     to view the certificate's details if you like, or skip that and type
 285     <tt class="userinput">0</tt> to enroll the key.</li>
 286
 287 <li>Back out of any directories you entered and return to the MokManager
 288     main menu.</li>
 289
 290 <li>Select <tt>Continue boot</tt> at the main menu.</li>
 291
 292 </ol>
 293
 294 <p>At this point the computer may boot into its default OS, reboot, or perhaps even hang. When you reboot it, though, rEFInd should start up in Secure Boot mode. (You can verify this by selecting the <i>About rEFInd</i> tool in the main menu. Check the <i>Platform</i> item in the resulting screen; it should verify that Secure Boot is active.) You should now be able to launch any boot loader signed with a key recognized by the firmware or by shim (including any MOKs you've enrolled). If you want to manage keys in the future, rEFInd displays a new icon in the second (tools) row you can use to launch MokManager. (This icon appears by default if MokManager is installed, but if you edit <tt>showtools</tt> in <tt>refind.conf</tt>, you must be sure to include <tt>mok_tool</tt> as an option in order to gain access to it.)</p>
 295
 296 <p>If you're using Ubuntu 12.10, you can't use its version of shim, but you can replace it with Garrett's shim. If you do so, though, you'll have to add Ubuntu's public key as a MOK, at least if you intend to launch Ubuntu's version of GRUB or launch Ubuntu-provided signed kernels. Ubuntu's public key is available in the <a href="http://archive.ubuntu.com/ubuntu/pool/main/s/shim/shim_0~20120906.bcd0a4e8-0ubuntu4.debian.tar.gz">shim_0~20120906.bcd0a4e8-0ubuntu4.debian.tar.gz</a> tarball, as <tt>canonical-uefi-ca.der</tt>. (The filename extensions <tt>.cer</tt> and <tt>.der</tt> are interchangeable for most purposes.) I've also included this key with rEFInd, in the <tt>refind/keys</tt> subdirectory of its package file. To use this key, copy it to your ESP and enroll it with MokManager. See <a href="http://falstaff.agner.ch/2012/12/12/secure-boot-implementation-of-ubuntu-12-10-quantal-quetzal/">this blog post</a> for further details on Ubuntu 12.10's handling of Secure Boot. In principle, you should be able to use shim 0.2 or later from future distributions that include it; but you must be sure that whatever you use supports MokManager.</p>
 297
 298 <a name="mok">
 299 <h2>Managing Your MOKs</h2>
 300 </a>
 301
 302 <p>The preceding instructions provided the basics of getting rEFInd up and running, including using MokManager to enroll a MOK on your computer. If you need to sign binaries, though, you'll have to use additional tools. The OpenSSL package provides the cryptographic tools necessary, but actually signing EFI binaries requires additional software. Two packages for this are available: <tt>sbsigntool</tt> and <tt>pesign</tt>. Both are available in binary form from <a href="https://build.opensuse.org/project/show?project=home%3Ajejb1%3AUEFI">this OpenSUSE Build Service (OBS)</a> repository. The following procedure uses <tt>sbsigntool</tt>. To sign your own binaries, follow these steps (you can skip the first five steps if you've used <tt>install.sh</tt>'s <tt>--localkeys</tt> option):</p>
 303
 304 <ol>
 305
 306 <li>If it's not already installed, install OpenSSL on your computer. (It
 307     normally comes in a package called <tt>openssl</tt>.)</li>
 308
 309 <li>If you did <i>not</i> re-sign your rEFInd binaries with
 310     <tt>install.sh</tt>'s <tt>--localkeys</tt> option, type the following
 311     two commands to generate your public and private keys:
 312
 313 <pre class="listing">
 314 $ <tt class="userinput">openssl req -new -x509 -newkey rsa:2048 -keyout refind_local.key \
 315   -out refind_local.crt -nodes -days 3650 -subj "/CN=Your Name/"</tt>
 316 $ <tt class="userinput">openssl x509 -in refind_local.crt -out refind_local.cer -outform DER</tt>
 317 </pre>
 318
 319     Change <tt>Your Name</tt> to your own name or other identifying
 320     characteristics, and adjust the certificate's time span (set via
 321     <tt>-days</tt>) as you see fit. If you omit the <tt>-nodes</tt> option,
 322     the program will prompt you for a passphrase for added security.
 323     Remember this, since you'll need it to sign your binaries. The result
 324     is a private key file (<tt>refind_local.key</tt>), which is highly
 325     sensitive since it's required to sign binaries, and two public keys
 326     (<tt>refind_local.crt</tt> and <tt>refind_local.cer</tt>), which can be
 327     used to verify signed binaries' authenticity. The two public key files
 328     are equivalent, but are used by different
 329     tools&mdash;<tt>sbsigntool</tt> uses <tt>refind_local.crt</tt> to sign
 330     binaries, but MokManager uses <tt>refind_local.cer</tt> to enroll the
 331     key. If you used <tt>install.sh</tt>'s <tt>--localkeys</tt> option,
 332     this step is unnecessary, since these keys have already been created
 333     and are stored in <tt>/etc/refind.d/keys</tt>.</li>
 334
 335 <li>Copy the three key files to a secure location and adjust permissions
 336     such that only you can read <tt>refind_local.key</tt>. You'll need
 337     these keys to sign future binaries, so don't discard them.</li>
 338
 339 <li>Copy the <tt>refind_local.cer</tt> file to your ESP, ideally to a
 340     location with few other files. (MokManager's user interface becomes
 341     unreliable when browsing directories with lots of files.)</li>
 342
 343 <li>Download and install the <tt>sbsigntool</tt> package. Binary links for
 344     various distributions are available from the <a
 345     href="https://build.opensuse.org/package/show?package=sbsigntools&project=home%3Ajejb1%3AUEFI">OpenSUSE
 346     Build Service</a>, or you can obtain the source code by typing <tt
 347     class="userinput">git clone
 348     git://kernel.ubuntu.com/jk/sbsigntool</tt>.</li>
 349
 350 <li>Sign your binary by typing <tt class="userinput">sbsign --key
 351     refind_local.key --cert refind_local.crt --output <tt
 352     class="variable">binary-signed.efi binary.efi</tt></tt>, adjusting the
 353     paths to the keys and the binary names.</li>
 354
 355 <li>Copy your signed binary to a suitable location on the ESP for rEFInd to
 356     locate it. Be sure to include any support files that it needs,
 357     too.</li>
 358
 359 <li>Check your <tt>refind.conf</tt> file to ensure that the
 360     <tt>showtools</tt> option is either commented out or includes
 361     <tt>mok_tool</tt> among its options.</li>
 362
 363 <li>Reboot. You can try launching the boot loader you just installed, but
 364     chances are it will generate an <tt>Access Denied</tt> message. For it
 365     to work, you must launch MokManager using the tool that rEFInd presents
 366     on its second row. You can then enroll your <tt>refind_local.cer</tt>
 367     key just as you enrolled the <tt>refind.cer</tt> key.</li>
 368
 369 </ol>
 370
 371 <p>At this point you should be able to launch the binaries you've signed. Unfortunately, there can still be problems at this point....</p>
 372
 373 <a name="caveats">
 374 <h2>Secure Boot Caveats</h2>
 375 </a>
 376
 377 <p>rEFInd's Secure Boot support is brand-new with version 0.5.0 of the program, and was revamped for version 0.6.2. I believe rEFInd 0.6.2's Secure Boot support to be significantly superior to that of previous versions, but you might still run into problems. Some issues you might encounter include the following:</p>
 378
 379 <ul>
 380
 381 <li>Under certain circumstances, the time required to launch a boot loader
 382     can increase. This is unlikely to be noticeable for the average small
 383     boot loader, but could be significant for larger boot loaders on slow
 384     filesystems, such as Linux kernels on ext2fs, ext3fs, or ReiserFS
 385     partitions.</li>
 386
 387 <li>As of version 0.6.2, rEFInd's own Secure Boot support is theoretically
 388     able to work on non-<i>x</i>86-64 platforms; however, shim 0.2 works
 389     only on <i>x</i>86-64, and rEFInd is dependent upon shim. Thus, you'll
 390     have to wait for future shim developments if you want to use Secure
 391     Boot on <i>x</i>86 or ARM computers.</li>
 392
 393 <li>In theory, signing Microsoft's boot loader with a MOK should work. This
 394     might be handy if you want to replace your computer's built-in keys
 395     with your own but still boot Windows&mdash;but be aware that if Windows
 396     replaces its boot loader, it will then stop working.</li>
 397
 398 </ul>
 399
 400 <p>If you launch a boot loader or other program from rEFInd that relies on the EFI's standard program-launching code, that program should take advantage of shim and its MOKs. For instance, if you launch <a href="http://freedesktop.org/wiki/Software/gummiboot">gummiboot</a> from rEFInd (and rEFInd from shim), gummiboot should be able to launch shim/MOK-signed Linux kernels. This is not currently true if you launch gummiboot directly from shim.</p>
 401
 402 <p>My focus in testing rEFInd's Secure Boot capabilities has been on getting Linux kernels with EFI stub loaders to launch correctly. I've done some minimal testing with GRUB 2, though. I've also tested some self-signed binaries, such as an EFI shell and MokManager. (The EFI shell launches, but will not itself launch anything that's not been signed with a UEFI Secure Boot key, even with rEFInd 0.6.2. This of course limits its utility.)</p>
 403
 404 <p>At the moment, I consider rEFInd's shim/MOK support to be of late alpha quality. I'm releasing it in this state in the hope of getting feedback from adventurous early adopters. Some of the usability improvements are dependent upon MOK-capable versions of shim being released with major distributions; such versions of shim, with kernels signed with the key that matches the one built into shim, will greatly reduce the need for users to sign boot loaders.</p>
 405
 406 <hr />
 407
 408 <p>copyright &copy; 2012&ndash;2013 by Roderick W. Smith</p>
 409
 410 <p>This document is licensed under the terms of the <a href="FDL-1.3.txt">GNU Free Documentation License (FDL), version 1.3.</a></p>
 411
 412 <p>If you have problems with or comments about this Web page, please e-mail me at <a href="mailto:rodsmith@rodsbooks.com">rodsmith@rodsbooks.com.</a> Thanks.</p>
 413
 414 <p><a href="index.html">Go to the main rEFInd page</a></p>
 415
 416 <p><a href="revisions.html">Learn about rEFInd's history</a></p>
 417
 418
 419   <p><a href="http://www.rodsbooks.com/">Return</a> to my main Web page.</p>
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