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23 <title>PKCS #11 (Cryptoki) support</title>
24 <para>PKCS #11 (Public Key Cryptography Standard #11) defines a
25 platform- independent API for the control of hardware security
26 modules (HSMs) and other cryptographic support devices.</para>
27 <para>BIND 9 is known to work with two HSMs: The Sun SCA 6000
28 cryptographic acceleration board, tested under Solaris x86, and
29 the AEP Keyper network-attached key storage device, tested with
30 Debian Linux, Solaris x86 and Windows Server 2003.</para>
32 <title>Prerequisites</title>
33 <para>See the HSM vendor documentation for information about
34 installing, initializing, testing and troubleshooting the
36 <para>BIND 9 uses OpenSSL for cryptography, but stock OpenSSL
37 does not yet fully support PKCS #11. However, a PKCS #11 engine
38 for OpenSSL is available from the OpenSolaris project. It has
39 been modified by ISC to work with with BIND 9, and to provide
40 new features such as PIN management and key by
42 <para>The patched OpenSSL depends on a "PKCS #11 provider".
43 This is a shared library object, providing a low-level PKCS #11
44 interface to the HSM hardware. It is dynamically loaded by
45 OpenSSL at runtime. The PKCS #11 provider comes from the HSM
46 vendor, and and is specific to the HSM to be controlled.</para>
47 <para>There are two "flavors" of PKCS #11 support provided by
48 the patched OpenSSL, one of which must be chosen at
49 configuration time. The correct choice depends on the HSM
53 <para>Use 'crypto-accelerator' with HSMs that have hardware
54 cryptographic acceleration features, such as the SCA 6000
55 board. This causes OpenSSL to run all supported
56 cryptographic operations in the HSM.</para>
59 <para>Use 'sign-only' with HSMs that are designed to
60 function primarily as secure key storage devices, but lack
61 hardware acceleration. These devices are highly secure, but
62 are not necessarily any faster at cryptography than the
63 system CPU — often, they are slower. It is therefore
64 most efficient to use them only for those cryptographic
65 functions that require access to the secured private key,
66 such as zone signing, and to use the system CPU for all
67 other computationally-intensive operations. The AEP Keyper
68 is an example of such a device.</para>
71 <para>The modified OpenSSL code is included in the BIND 9 release,
72 in the form of a context diff against the latest verions of
73 OpenSSL. OpenSSL 0.9.8 and 1.0.0 are both supported; there are
74 separate diffs for each version. In the examples to follow,
75 we use OpenSSL 0.9.8, but the same methods work with OpenSSL 1.0.0.
78 The latest OpenSSL versions at the time of the BIND release
79 are 0.9.8s and 1.0.0f.
80 ISC will provide an updated patch as new versions of OpenSSL
81 are released. The version number in the following examples
82 is expected to change.</note>
84 Before building BIND 9 with PKCS #11 support, it will be
85 necessary to build OpenSSL with this patch in place and inform
86 it of the path to the HSM-specific PKCS #11 provider
88 <para>Obtain OpenSSL 0.9.8s:</para>
90 $ <userinput>wget <ulink>http://www.openssl.org/source/openssl-0.9.8s.tar.gz</ulink></userinput>
92 <para>Extract the tarball:</para>
94 $ <userinput>tar zxf openssl-0.9.8s.tar.gz</userinput>
96 <para>Apply the patch from the BIND 9 release:</para>
98 $ <userinput>patch -p1 -d openssl-0.9.8s \
99 < bind9/bin/pkcs11/openssl-0.9.8s-patch</userinput>
101 <note>(Note that the patch file may not be compatible with the
102 "patch" utility on all operating systems. You may need to
103 install GNU patch.)</note>
104 <para>When building OpenSSL, place it in a non-standard
105 location so that it does not interfere with OpenSSL libraries
106 elsewhere on the system. In the following examples, we choose
107 to install into "/opt/pkcs11/usr". We will use this location
108 when we configure BIND 9.</para>
111 <title>Building OpenSSL for the AEP Keyper on Linux</title>
112 <para>The AEP Keyper is a highly secure key storage device,
113 but does not provide hardware cryptographic acceleration. It
114 can carry out cryptographic operations, but it is probably
115 slower than your system's CPU. Therefore, we choose the
116 'sign-only' flavor when building OpenSSL.</para>
117 <para>The Keyper-specific PKCS #11 provider library is
118 delivered with the Keyper software. In this example, we place
119 it /opt/pkcs11/usr/lib:</para>
121 $ <userinput>cp pkcs11.GCC4.0.2.so.4.05 /opt/pkcs11/usr/lib/libpkcs11.so</userinput>
123 <para>This library is only available for Linux as a 32-bit
124 binary. If we are compiling on a 64-bit Linux system, it is
125 necessary to force a 32-bit build, by specifying -m32 in the
126 build options.</para>
127 <para>Finally, the Keyper library requires threads, so we
128 must specify -pthread.</para>
130 $ <userinput>cd openssl-0.9.8s</userinput>
131 $ <userinput>./Configure linux-generic32 -m32 -pthread \
132 --pk11-libname=/opt/pkcs11/usr/lib/libpkcs11.so \
133 --pk11-flavor=sign-only \
134 --prefix=/opt/pkcs11/usr</userinput>
136 <para>After configuring, run "<command>make</command>"
137 and "<command>make test</command>". If "<command>make
138 test</command>" fails with "pthread_atfork() not found", you forgot to
139 add the -pthread above.</para>
143 <title>Building OpenSSL for the SCA 6000 on Solaris</title>
144 <para>The SCA-6000 PKCS #11 provider is installed as a system
145 library, libpkcs11. It is a true crypto accelerator, up to 4
146 times faster than any CPU, so the flavor shall be
147 'crypto-accelerator'.</para>
148 <para>In this example, we are building on Solaris x86 on an
151 $ <userinput>cd openssl-0.9.8s</userinput>
152 $ <userinput>./Configure solaris64-x86_64-cc \
153 --pk11-libname=/usr/lib/64/libpkcs11.so \
154 --pk11-flavor=crypto-accelerator \
155 --prefix=/opt/pkcs11/usr</userinput>
157 <para>(For a 32-bit build, use "solaris-x86-cc" and
158 /usr/lib/libpkcs11.so.)</para>
159 <para>After configuring, run
160 <command>make</command> and
161 <command>make test</command>.</para>
165 <title>Building OpenSSL for SoftHSM</title>
166 <para>SoftHSM is a software library provided by the OpenDNSSEC
167 project (http://www.opendnssec.org) which provides a PKCS#11
168 interface to a virtual HSM, implemented in the form of encrypted
169 data on the local filesystem. It uses the Botan library for
170 encryption and SQLite3 for data storage. Though less secure
171 than a true HSM, it can provide more secure key storage than
172 traditional key files, and can allow you to experiment with
173 PKCS#11 when an HSM is not available.</para>
174 <para>The SoftHSM cryptographic store must be installed and
175 initialized before using it with OpenSSL, and the SOFTHSM_CONF
176 environment variable must always point to the SoftHSM configuration
179 $ <userinput> cd softhsm-1.3.0 </userinput>
180 $ <userinput> configure --prefix=/opt/pkcs11/usr </userinput>
181 $ <userinput> make </userinput>
182 $ <userinput> make install </userinput>
183 $ <userinput> export SOFTHSM_CONF=/opt/pkcs11/softhsm.conf </userinput>
184 $ <userinput> echo "0:/opt/pkcs11/softhsm.db" > $SOFTHSM_CONF </userinput>
185 $ <userinput> /opt/pkcs11/usr/bin/softhsm --init-token 0 --slot 0 --label softhsm </userinput>
187 <para>SoftHSM can perform all cryptographic operations, but
188 since it only uses your system CPU, there is no need to use it
189 for anything but signing. Therefore, we choose the 'sign-only'
190 flavor when building OpenSSL.</para>
192 $ <userinput>cd openssl-0.9.8s</userinput>
193 $ <userinput>./Configure linux-x86_64 -pthread \
194 --pk11-libname=/opt/pkcs11/usr/lib/libpkcs11.so \
195 --pk11-flavor=sign-only \
196 --prefix=/opt/pkcs11/usr</userinput>
198 <para>After configuring, run "<command>make</command>"
199 and "<command>make test</command>".</para>
201 <para>Once you have built OpenSSL, run
202 "<command>apps/openssl engine pkcs11</command>" to confirm
203 that PKCS #11 support was compiled in correctly. The output
204 should be one of the following lines, depending on the flavor
207 (pkcs11) PKCS #11 engine support (sign only)
211 (pkcs11) PKCS #11 engine support (crypto accelerator)
214 "<command>apps/openssl engine pkcs11 -t</command>". This will
215 attempt to initialize the PKCS #11 engine. If it is able to
216 do so successfully, it will report
217 <quote><literal>[ available ]</literal></quote>.</para>
218 <para>If the output is correct, run
219 "<command>make install</command>" which will install the
220 modified OpenSSL suite to
221 <filename>/opt/pkcs11/usr</filename>.</para>
224 <title>Building BIND 9 with PKCS#11</title>
225 <para>When building BIND 9, the location of the custom-built
226 OpenSSL library must be specified via configure.</para>
229 <title>Configuring BIND 9 for Linux with the AEP Keyper</title>
230 <para>To link with the PKCS #11 provider, threads must be
231 enabled in the BIND 9 build.</para>
232 <para>The PKCS #11 library for the AEP Keyper is currently
233 only available as a 32-bit binary. If we are building on a
234 64-bit host, we must force a 32-bit build by adding "-m32" to
235 the CC options on the "configure" command line.</para>
237 $ <userinput>cd ../bind9</userinput>
238 $ <userinput>./configure CC="gcc -m32" --enable-threads \
239 --with-openssl=/opt/pkcs11/usr \
240 --with-pkcs11=/opt/pkcs11/usr/lib/libpkcs11.so</userinput>
245 <title>Configuring BIND 9 for Solaris with the SCA 6000</title>
246 <para>To link with the PKCS #11 provider, threads must be
247 enabled in the BIND 9 build.</para>
249 $ <userinput>cd ../bind9</userinput>
250 $ <userinput>./configure CC="cc -xarch=amd64" --enable-threads \
251 --with-openssl=/opt/pkcs11/usr \
252 --with-pkcs11=/usr/lib/64/libpkcs11.so</userinput>
254 <para>(For a 32-bit build, omit CC="cc -xarch=amd64".)</para>
255 <para>If configure complains about OpenSSL not working, you
256 may have a 32/64-bit architecture mismatch. Or, you may have
257 incorrectly specified the path to OpenSSL (it should be the
258 same as the --prefix argument to the OpenSSL
263 <title>Configuring BIND 9 for SoftHSM</title>
265 $ <userinput>cd ../bind9</userinput>
266 $ <userinput>./configure --enable-threads \
267 --with-openssl=/opt/pkcs11/usr \
268 --with-pkcs11=/opt/pkcs11/usr/lib/libpkcs11.so</userinput>
271 <para>After configuring, run
272 "<command>make</command>",
273 "<command>make test</command>" and
274 "<command>make install</command>".</para>
275 <para>(Note: If "make test" fails in the "pkcs11" system test, you may
276 have forgotten to set the SOFTHSM_CONF environment variable.)</para>
279 <title>PKCS #11 Tools</title>
280 <para>BIND 9 includes a minimal set of tools to operate the
282 <command>pkcs11-keygen</command> to generate a new key pair
284 <command>pkcs11-list</command> to list objects currently
286 <command>pkcs11-destroy</command> to remove objects.</para>
287 <para>In UNIX/Linux builds, these tools are built only if BIND
288 9 is configured with the --with-pkcs11 option. (NOTE: If
289 --with-pkcs11 is set to "yes", rather than to the path of the
290 PKCS #11 provider, then the tools will be built but the
291 provider will be left undefined. Use the -m option or the
292 PKCS11_PROVIDER environment variable to specify the path to the
296 <title>Using the HSM</title>
297 <para>First, we must set up the runtime environment so the
298 OpenSSL and PKCS #11 libraries can be loaded:</para>
300 $ <userinput>export LD_LIBRARY_PATH=/opt/pkcs11/usr/lib:${LD_LIBRARY_PATH}</userinput>
302 <para>When operating an AEP Keyper, it is also necessary to
303 specify the location of the "machine" file, which stores
304 information about the Keyper for use by PKCS #11 provider
305 library. If the machine file is in
306 <filename>/opt/Keyper/PKCS11Provider/machine</filename>,
309 $ <userinput>export KEYPER_LIBRARY_PATH=/opt/Keyper/PKCS11Provider</userinput>
311 <!-- TODO: why not defined at compile time? -->
312 <para>These environment variables must be set whenever running
313 any tool that uses the HSM, including
314 <command>pkcs11-keygen</command>,
315 <command>pkcs11-list</command>,
316 <command>pkcs11-destroy</command>,
317 <command>dnssec-keyfromlabel</command>,
318 <command>dnssec-signzone</command>,
319 <command>dnssec-keygen</command>(which will use the HSM for
320 random number generation), and
321 <command>named</command>.</para>
322 <para>We can now create and use keys in the HSM. In this case,
323 we will create a 2048 bit key and give it the label
326 $ <userinput>pkcs11-keygen -b 2048 -l sample-ksk</userinput>
328 <para>To confirm that the key exists:</para>
330 $ <userinput>pkcs11-list</userinput>
332 object[0]: handle 2147483658 class 3 label[8] 'sample-ksk' id[0]
333 object[1]: handle 2147483657 class 2 label[8] 'sample-ksk' id[0]
335 <para>Before using this key to sign a zone, we must create a
336 pair of BIND 9 key files. The "dnssec-keyfromlabel" utility
337 does this. In this case, we will be using the HSM key
338 "sample-ksk" as the key-signing key for "example.net":</para>
340 $ <userinput>dnssec-keyfromlabel -l sample-ksk -f KSK example.net</userinput>
342 <para>The resulting K*.key and K*.private files can now be used
343 to sign the zone. Unlike normal K* files, which contain both
344 public and private key data, these files will contain only the
345 public key data, plus an identifier for the private key which
346 remains stored within the HSM. The HSM handles signing with the
348 <para>If you wish to generate a second key in the HSM for use
349 as a zone-signing key, follow the same procedure above, using a
350 different keylabel, a smaller key size, and omitting "-f KSK"
351 from the dnssec-keyfromlabel arguments:</para>
353 $ <userinput>pkcs11-keygen -b 1024 -l sample-zsk</userinput>
354 $ <userinput>dnssec-keyfromlabel -l sample-zsk example.net</userinput>
356 <para>Alternatively, you may prefer to generate a conventional
357 on-disk key, using dnssec-keygen:</para>
359 $ <userinput>dnssec-keygen example.net</userinput>
361 <para>This provides less security than an HSM key, but since
362 HSMs can be slow or cumbersome to use for security reasons, it
363 may be more efficient to reserve HSM keys for use in the less
364 frequent key-signing operation. The zone-signing key can be
365 rolled more frequently, if you wish, to compensate for a
366 reduction in key security.</para>
367 <para>Now you can sign the zone. (Note: If not using the -S
369 <command>dnssec-signzone</command>, it will be necessary to add
371 <filename>K*.key</filename> files to the zone master file before
374 $ <userinput>dnssec-signzone -S example.net</userinput>
376 Verifying the zone using the following algorithms:
378 Zone signing complete:
379 Algorithm: NSEC3RSASHA1: ZSKs: 1, KSKs: 1 active, 0 revoked, 0 stand-by
384 <title>Specifying the engine on the command line</title>
385 <para>The OpenSSL engine can be specified in
386 <command>named</command> and all of the BIND
387 <command>dnssec-*</command> tools by using the "-E
388 <engine>" command line option. If BIND 9 is built with
389 the --with-pkcs11 option, this option defaults to "pkcs11".
390 Specifying the engine will generally not be necessary unless
391 for some reason you wish to use a different OpenSSL
393 <para>If you wish to disable use of the "pkcs11" engine —
394 for troubleshooting purposes, or because the HSM is unavailable
395 — set the engine to the empty string. For example:</para>
397 $ <userinput>dnssec-signzone -E '' -S example.net</userinput>
400 <command>dnssec-signzone</command> to run as if it were compiled
401 without the --with-pkcs11 option.</para>
404 <title>Running named with automatic zone re-signing</title>
406 <command>named</command> to dynamically re-sign zones using HSM
407 keys, and/or to to sign new records inserted via nsupdate, then
408 named must have access to the HSM PIN. This can be accomplished
409 by placing the PIN into the openssl.cnf file (in the above
411 <filename>/opt/pkcs11/usr/ssl/openssl.cnf</filename>).</para>
412 <para>The location of the openssl.cnf file can be overridden by
413 setting the OPENSSL_CONF environment variable before running
415 <para>Sample openssl.cnf:</para>
417 openssl_conf = openssl_def
419 engines = engine_section
421 pkcs11 = pkcs11_section
423 PIN = <replaceable><PLACE PIN HERE></replaceable>
425 <para>This will also allow the dnssec-* tools to access the HSM
426 without PIN entry. (The pkcs11-* tools access the HSM directly,
427 not via OpenSSL, so a PIN will still be required to use
430 If the PIN is not known, I believe the first time named needs the
431 PIN to open a key, it'll ask you to type in the PIN, which will be
432 a problem because it probably won't be running on a terminal
435 <para>Placing the HSM's PIN in a text file in
436 this manner may reduce the security advantage of using an
437 HSM. Be sure this is what you want to do before configuring
438 OpenSSL in this way.</para>
441 <!-- TODO: what is alternative then for named dynamic re-signing? -->
442 <!-- TODO: what happens if PIN is not known? named will log about it? -->