]>
Commit | Line | Data |
---|---|---|
f9a7c34f UM |
1 | OpenSSL - Frequently Asked Questions |
2 | -------------------------------------- | |
3 | ||
0ae485dc RL |
4 | [MISC] Miscellaneous questions |
5 | ||
49976df5 | 6 | * Which is the current version of OpenSSL? |
f9a7c34f UM |
7 | * Where is the documentation? |
8 | * How can I contact the OpenSSL developers? | |
0ae485dc RL |
9 | * Where can I get a compiled version of OpenSSL? |
10 | * Why aren't tools like 'autoconf' and 'libtool' used? | |
9c11a0e5 | 11 | * What is an 'engine' version? |
d4e573f3 | 12 | * How do I check the authenticity of the OpenSSL distribution? |
2131ce57 | 13 | * How does the versioning scheme work? |
0ae485dc RL |
14 | |
15 | [LEGAL] Legal questions | |
16 | ||
c1ce32f1 | 17 | * Do I need patent licenses to use OpenSSL? |
17e75747 | 18 | * Can I use OpenSSL with GPL software? |
0ae485dc RL |
19 | |
20 | [USER] Questions on using the OpenSSL applications | |
21 | ||
f9a7c34f | 22 | * Why do I get a "PRNG not seeded" error message? |
24cc290b | 23 | * Why do I get an "unable to write 'random state'" error message? |
46e80a30 DSH |
24 | * How do I create certificates or certificate requests? |
25 | * Why can't I create certificate requests? | |
afee764c | 26 | * Why does <SSL program> fail with a certificate verify error? |
a331a305 | 27 | * Why can I only use weak ciphers when I connect to a server using OpenSSL? |
afee764c DSH |
28 | * How can I create DSA certificates? |
29 | * Why can't I make an SSL connection using a DSA certificate? | |
a331a305 | 30 | * How can I remove the passphrase on a private key? |
1a7b2d33 | 31 | * Why can't I use OpenSSL certificates with SSL client authentication? |
7522254b | 32 | * Why does my browser give a warning about a mismatched hostname? |
0b33bc6b | 33 | * How do I install a CA certificate into a browser? |
17e2c77a | 34 | * Why is OpenSSL x509 DN output not conformant to RFC2253? |
09b6c2ef | 35 | * What is a "128 bit certificate"? Can I create one with OpenSSL? |
a070f0da | 36 | * Why does OpenSSL set the authority key identifier extension incorrectly? |
2cd81830 | 37 | * How can I set up a bundle of commercial root CA certificates? |
0ae485dc RL |
38 | |
39 | [BUILD] Questions about building and testing OpenSSL | |
40 | ||
41 | * Why does the linker complain about undefined symbols? | |
c32364f5 | 42 | * Why does the OpenSSL test fail with "bc: command not found"? |
a6ed5dd6 | 43 | * Why does the OpenSSL test fail with "bc: 1 no implemented"? |
f742e497 | 44 | * Why does the OpenSSL test fail with "bc: stack empty"? |
6bc847e4 | 45 | * Why does the OpenSSL compilation fail on Alpha Tru64 Unix? |
b364e5d2 | 46 | * Why does the OpenSSL compilation fail with "ar: command not found"? |
bf55ece1 | 47 | * Why does the OpenSSL compilation fail on Win32 with VC++? |
c4da6dd3 | 48 | * What is special about OpenSSL on Redhat? |
311e2099 RL |
49 | * Why does the OpenSSL compilation fail on MacOS X? |
50 | * Why does the OpenSSL test suite fail on MacOS X? | |
26a60b2e | 51 | * Why does the OpenSSL test suite fail in BN_sqr test [on a 64-bit platform]? |
75c40285 | 52 | * Why does OpenBSD-i386 build fail on des-586.s with "Unimplemented segment type"? |
851e31ff | 53 | * Why does the OpenSSL test suite fail in sha512t on x86 CPU? |
4b559868 | 54 | * Why does compiler fail to compile sha512.c? |
65613f23 | 55 | * Test suite still fails, what to do? |
c25a0aae DSH |
56 | * I think I've found a bug, what should I do? |
57 | * I'm SURE I've found a bug, how do I report it? | |
58 | * I've found a security issue, how do I report it? | |
f9a7c34f | 59 | |
0ae485dc RL |
60 | [PROG] Questions about programming with OpenSSL |
61 | ||
62 | * Is OpenSSL thread-safe? | |
63 | * I've compiled a program under Windows and it crashes: why? | |
64 | * How do I read or write a DER encoded buffer using the ASN1 functions? | |
6ef7b78e | 65 | * OpenSSL uses DER but I need BER format: does OpenSSL support BER? |
0ae485dc RL |
66 | * I've tried using <M_some_evil_pkcs12_macro> and I get errors why? |
67 | * I've called <some function> and it fails, why? | |
68 | * I just get a load of numbers for the error output, what do they mean? | |
69 | * Why do I get errors about unknown algorithms? | |
70 | * Why can't the OpenSSH configure script detect OpenSSL? | |
71 | * Can I use OpenSSL's SSL library with non-blocking I/O? | |
19732245 | 72 | * Why doesn't my server application receive a client certificate? |
e1f7ea25 | 73 | * Why does compilation fail due to an undefined symbol NID_uniqueIdentifier? |
6ef7b78e | 74 | * I think I've detected a memory leak, is this a bug? |
7bbce697 | 75 | * Why does Valgrind complain about the use of uninitialized data? |
715020e3 | 76 | * Why doesn't a memory BIO work when a file does? |
dd57b657 | 77 | * Where are the declarations and implementations of d2i_X509() etc? |
0ae485dc RL |
78 | |
79 | =============================================================================== | |
80 | ||
81 | [MISC] ======================================================================== | |
f9a7c34f | 82 | |
49976df5 UM |
83 | * Which is the current version of OpenSSL? |
84 | ||
85 | The current version is available from <URL: http://www.openssl.org>. | |
7e47a695 | 86 | OpenSSL 1.0.1e was released on Feb 11, 2013. |
49976df5 UM |
87 | |
88 | In addition to the current stable release, you can also access daily | |
89 | snapshots of the OpenSSL development version at <URL: | |
9fa24352 | 90 | ftp://ftp.openssl.org/snapshot/>, or get it by anonymous Git access. |
49976df5 UM |
91 | |
92 | ||
f9a7c34f UM |
93 | * Where is the documentation? |
94 | ||
95 | OpenSSL is a library that provides cryptographic functionality to | |
96 | applications such as secure web servers. Be sure to read the | |
97 | documentation of the application you want to use. The INSTALL file | |
98 | explains how to install this library. | |
99 | ||
100 | OpenSSL includes a command line utility that can be used to perform a | |
101 | variety of cryptographic functions. It is described in the openssl(1) | |
2693812d DSH |
102 | manpage. Documentation for developers is currently being written. Many |
103 | manual pages are available; overviews over libcrypto and | |
f9a7c34f UM |
104 | libssl are given in the crypto(3) and ssl(3) manpages. |
105 | ||
106 | The OpenSSL manpages are installed in /usr/local/ssl/man/ (or a | |
107 | different directory if you specified one as described in INSTALL). | |
108 | In addition, you can read the most current versions at | |
2693812d DSH |
109 | <URL: http://www.openssl.org/docs/>. Note that the online documents refer |
110 | to the very latest development versions of OpenSSL and may include features | |
111 | not present in released versions. If in doubt refer to the documentation | |
597dab0f DSH |
112 | that came with the version of OpenSSL you are using. The pod format |
113 | documentation is included in each OpenSSL distribution under the docs | |
114 | directory. | |
f9a7c34f UM |
115 | |
116 | For information on parts of libcrypto that are not yet documented, you | |
117 | might want to read Ariel Glenn's documentation on SSLeay 0.9, OpenSSL's | |
118 | predecessor, at <URL: http://www.columbia.edu/~ariel/ssleay/>. Much | |
119 | of this still applies to OpenSSL. | |
120 | ||
fbb41ae0 DSH |
121 | There is some documentation about certificate extensions and PKCS#12 |
122 | in doc/openssl.txt | |
123 | ||
f9a7c34f | 124 | The original SSLeay documentation is included in OpenSSL as |
cacbb51e | 125 | doc/ssleay.txt. It may be useful when none of the other resources |
f9a7c34f UM |
126 | help, but please note that it reflects the obsolete version SSLeay |
127 | 0.6.6. | |
128 | ||
129 | ||
130 | * How can I contact the OpenSSL developers? | |
131 | ||
132 | The README file describes how to submit bug reports and patches to | |
133 | OpenSSL. Information on the OpenSSL mailing lists is available from | |
134 | <URL: http://www.openssl.org>. | |
135 | ||
136 | ||
0ae485dc | 137 | * Where can I get a compiled version of OpenSSL? |
f9a7c34f | 138 | |
d9f40bbe | 139 | You can finder pointers to binary distributions in |
1676bec9 | 140 | <URL: http://www.openssl.org/related/binaries.html> . |
d9f40bbe | 141 | |
0ae485dc RL |
142 | Some applications that use OpenSSL are distributed in binary form. |
143 | When using such an application, you don't need to install OpenSSL | |
144 | yourself; the application will include the required parts (e.g. DLLs). | |
f9a7c34f | 145 | |
d9f40bbe | 146 | If you want to build OpenSSL on a Windows system and you don't have |
0ae485dc RL |
147 | a C compiler, read the "Mingw32" section of INSTALL.W32 for information |
148 | on how to obtain and install the free GNU C compiler. | |
f9a7c34f | 149 | |
0ae485dc | 150 | A number of Linux and *BSD distributions include OpenSSL. |
f9a7c34f | 151 | |
f9a7c34f | 152 | |
0ae485dc | 153 | * Why aren't tools like 'autoconf' and 'libtool' used? |
f9a7c34f | 154 | |
ba93fd6a UM |
155 | autoconf will probably be used in future OpenSSL versions. If it was |
156 | less Unix-centric, it might have been used much earlier. | |
f9a7c34f | 157 | |
a0256f46 | 158 | * What is an 'engine' version? |
679df234 LJ |
159 | |
160 | With version 0.9.6 OpenSSL was extended to interface to external crypto | |
161 | hardware. This was realized in a special release '0.9.6-engine'. With | |
034bae10 NL |
162 | version 0.9.7 the changes were merged into the main development line, |
163 | so that the special release is no longer necessary. | |
b1d6e3f5 | 164 | |
d4e573f3 RL |
165 | * How do I check the authenticity of the OpenSSL distribution? |
166 | ||
167 | We provide MD5 digests and ASC signatures of each tarball. | |
168 | Use MD5 to check that a tarball from a mirror site is identical: | |
169 | ||
170 | md5sum TARBALL | awk '{print $1;}' | cmp - TARBALL.md5 | |
171 | ||
172 | You can check authenticity using pgp or gpg. You need the OpenSSL team | |
e6e1f4cb MC |
173 | member public key used to sign it (download it from a key server, see a |
174 | list of keys at <URL: http://www.openssl.org/about/>). Then | |
d4e573f3 RL |
175 | just do: |
176 | ||
177 | pgp TARBALL.asc | |
178 | ||
2131ce57 DSH |
179 | * How does the versioning scheme work? |
180 | ||
181 | After the release of OpenSSL 1.0.0 the versioning scheme changed. Letter | |
182 | releases (e.g. 1.0.1a) can only contain bug and security fixes and no | |
183 | new features. Minor releases change the last number (e.g. 1.0.2) and | |
184 | can contain new features that retain binary compatibility. Changes to | |
185 | the middle number are considered major releases and neither source nor | |
186 | binary compatibility is guaranteed. | |
187 | ||
188 | Therefore the answer to the common question "when will feature X be | |
189 | backported to OpenSSL 1.0.0/0.9.8?" is "never" but it could appear | |
190 | in the next minor release. | |
191 | ||
2527b94f DSH |
192 | * What happens when the letter release reaches z? |
193 | ||
194 | It was decided after the release of OpenSSL 0.9.8y the next version should | |
195 | be 0.9.8za then 0.9.8zb and so on. | |
196 | ||
197 | ||
0ae485dc | 198 | [LEGAL] ======================================================================= |
b1d6e3f5 | 199 | |
0ae485dc | 200 | * Do I need patent licenses to use OpenSSL? |
b1d6e3f5 | 201 | |
0ae485dc RL |
202 | The patents section of the README file lists patents that may apply to |
203 | you if you want to use OpenSSL. For information on intellectual | |
204 | property rights, please consult a lawyer. The OpenSSL team does not | |
205 | offer legal advice. | |
206 | ||
af1048c2 BM |
207 | You can configure OpenSSL so as not to use IDEA, MDC2 and RC5 by using |
208 | ./config no-idea no-mdc2 no-rc5 | |
0ae485dc RL |
209 | |
210 | ||
17e75747 UM |
211 | * Can I use OpenSSL with GPL software? |
212 | ||
213 | On many systems including the major Linux and BSD distributions, yes (the | |
214 | GPL does not place restrictions on using libraries that are part of the | |
215 | normal operating system distribution). | |
216 | ||
217 | On other systems, the situation is less clear. Some GPL software copyright | |
218 | holders claim that you infringe on their rights if you use OpenSSL with | |
219 | their software on operating systems that don't normally include OpenSSL. | |
220 | ||
221 | If you develop open source software that uses OpenSSL, you may find it | |
e3fefbfd | 222 | useful to choose an other license than the GPL, or state explicitly that |
17e75747 UM |
223 | "This program is released under the GPL with the additional exemption that |
224 | compiling, linking, and/or using OpenSSL is allowed." If you are using | |
225 | GPL software developed by others, you may want to ask the copyright holder | |
226 | for permission to use their software with OpenSSL. | |
227 | ||
228 | ||
0ae485dc | 229 | [USER] ======================================================================== |
b1d6e3f5 | 230 | |
f9a7c34f UM |
231 | * Why do I get a "PRNG not seeded" error message? |
232 | ||
233 | Cryptographic software needs a source of unpredictable data to work | |
234 | correctly. Many open source operating systems provide a "randomness | |
c09a2978 BM |
235 | device" (/dev/urandom or /dev/random) that serves this purpose. |
236 | All OpenSSL versions try to use /dev/urandom by default; starting with | |
379e5689 | 237 | version 0.9.7, OpenSSL also tries /dev/random if /dev/urandom is not |
c09a2978 BM |
238 | available. |
239 | ||
240 | On other systems, applications have to call the RAND_add() or | |
241 | RAND_seed() function with appropriate data before generating keys or | |
242 | performing public key encryption. (These functions initialize the | |
243 | pseudo-random number generator, PRNG.) Some broken applications do | |
244 | not do this. As of version 0.9.5, the OpenSSL functions that need | |
245 | randomness report an error if the random number generator has not been | |
246 | seeded with at least 128 bits of randomness. If this error occurs and | |
247 | is not discussed in the documentation of the application you are | |
248 | using, please contact the author of that application; it is likely | |
249 | that it never worked correctly. OpenSSL 0.9.5 and later make the | |
250 | error visible by refusing to perform potentially insecure encryption. | |
251 | ||
252 | If you are using Solaris 8, you can add /dev/urandom and /dev/random | |
253 | devices by installing patch 112438 (Sparc) or 112439 (x86), which are | |
254 | available via the Patchfinder at <URL: http://sunsolve.sun.com> | |
255 | (Solaris 9 includes these devices by default). For /dev/random support | |
256 | for earlier Solaris versions, see Sun's statement at | |
257 | <URL: http://sunsolve.sun.com/pub-cgi/retrieve.pl?doc=fsrdb/27606&zone_32=SUNWski> | |
258 | (the SUNWski package is available in patch 105710). | |
8311d323 | 259 | |
d9a770e6 BM |
260 | On systems without /dev/urandom and /dev/random, it is a good idea to |
261 | use the Entropy Gathering Demon (EGD); see the RAND_egd() manpage for | |
262 | details. Starting with version 0.9.7, OpenSSL will automatically look | |
263 | for an EGD socket at /var/run/egd-pool, /dev/egd-pool, /etc/egd-pool and | |
264 | /etc/entropy. | |
2b670ea2 | 265 | |
24cc290b BM |
266 | Most components of the openssl command line utility automatically try |
267 | to seed the random number generator from a file. The name of the | |
268 | default seeding file is determined as follows: If environment variable | |
269 | RANDFILE is set, then it names the seeding file. Otherwise if | |
270 | environment variable HOME is set, then the seeding file is $HOME/.rnd. | |
271 | If neither RANDFILE nor HOME is set, versions up to OpenSSL 0.9.6 will | |
272 | use file .rnd in the current directory while OpenSSL 0.9.6a uses no | |
273 | default seeding file at all. OpenSSL 0.9.6b and later will behave | |
6af59bc0 | 274 | similarly to 0.9.6a, but will use a default of "C:\" for HOME on |
24cc290b BM |
275 | Windows systems if the environment variable has not been set. |
276 | ||
277 | If the default seeding file does not exist or is too short, the "PRNG | |
278 | not seeded" error message may occur. | |
279 | ||
280 | The openssl command line utility will write back a new state to the | |
281 | default seeding file (and create this file if necessary) unless | |
282 | there was no sufficient seeding. | |
283 | ||
35feed50 LJ |
284 | Pointing $RANDFILE to an Entropy Gathering Daemon socket does not work. |
285 | Use the "-rand" option of the OpenSSL command line tools instead. | |
286 | The $RANDFILE environment variable and $HOME/.rnd are only used by the | |
287 | OpenSSL command line tools. Applications using the OpenSSL library | |
288 | provide their own configuration options to specify the entropy source, | |
289 | please check out the documentation coming the with application. | |
8311d323 | 290 | |
2b670ea2 | 291 | |
24cc290b BM |
292 | * Why do I get an "unable to write 'random state'" error message? |
293 | ||
294 | ||
295 | Sometimes the openssl command line utility does not abort with | |
296 | a "PRNG not seeded" error message, but complains that it is | |
297 | "unable to write 'random state'". This message refers to the | |
298 | default seeding file (see previous answer). A possible reason | |
299 | is that no default filename is known because neither RANDFILE | |
300 | nor HOME is set. (Versions up to 0.9.6 used file ".rnd" in the | |
301 | current directory in this case, but this has changed with 0.9.6a.) | |
302 | ||
303 | ||
0ae485dc RL |
304 | * How do I create certificates or certificate requests? |
305 | ||
306 | Check out the CA.pl(1) manual page. This provides a simple wrapper round | |
307 | the 'req', 'verify', 'ca' and 'pkcs12' utilities. For finer control check | |
308 | out the manual pages for the individual utilities and the certificate | |
597dab0f | 309 | extensions documentation (in ca(1), req(1), x509v3_config(5) ) |
0ae485dc RL |
310 | |
311 | ||
312 | * Why can't I create certificate requests? | |
313 | ||
314 | You typically get the error: | |
315 | ||
316 | unable to find 'distinguished_name' in config | |
317 | problems making Certificate Request | |
318 | ||
319 | This is because it can't find the configuration file. Check out the | |
320 | DIAGNOSTICS section of req(1) for more information. | |
321 | ||
322 | ||
323 | * Why does <SSL program> fail with a certificate verify error? | |
324 | ||
325 | This problem is usually indicated by log messages saying something like | |
326 | "unable to get local issuer certificate" or "self signed certificate". | |
327 | When a certificate is verified its root CA must be "trusted" by OpenSSL | |
328 | this typically means that the CA certificate must be placed in a directory | |
329 | or file and the relevant program configured to read it. The OpenSSL program | |
330 | 'verify' behaves in a similar way and issues similar error messages: check | |
331 | the verify(1) program manual page for more information. | |
332 | ||
333 | ||
334 | * Why can I only use weak ciphers when I connect to a server using OpenSSL? | |
335 | ||
336 | This is almost certainly because you are using an old "export grade" browser | |
337 | which only supports weak encryption. Upgrade your browser to support 128 bit | |
338 | ciphers. | |
339 | ||
340 | ||
341 | * How can I create DSA certificates? | |
342 | ||
343 | Check the CA.pl(1) manual page for a DSA certificate example. | |
344 | ||
345 | ||
346 | * Why can't I make an SSL connection to a server using a DSA certificate? | |
347 | ||
348 | Typically you'll see a message saying there are no shared ciphers when | |
349 | the same setup works fine with an RSA certificate. There are two possible | |
350 | causes. The client may not support connections to DSA servers most web | |
351 | browsers (including Netscape and MSIE) only support connections to servers | |
352 | supporting RSA cipher suites. The other cause is that a set of DH parameters | |
353 | has not been supplied to the server. DH parameters can be created with the | |
354 | dhparam(1) command and loaded using the SSL_CTX_set_tmp_dh() for example: | |
355 | check the source to s_server in apps/s_server.c for an example. | |
356 | ||
357 | ||
358 | * How can I remove the passphrase on a private key? | |
359 | ||
360 | Firstly you should be really *really* sure you want to do this. Leaving | |
361 | a private key unencrypted is a major security risk. If you decide that | |
362 | you do have to do this check the EXAMPLES sections of the rsa(1) and | |
363 | dsa(1) manual pages. | |
364 | ||
365 | ||
1a7b2d33 DSH |
366 | * Why can't I use OpenSSL certificates with SSL client authentication? |
367 | ||
368 | What will typically happen is that when a server requests authentication | |
369 | it will either not include your certificate or tell you that you have | |
370 | no client certificates (Netscape) or present you with an empty list box | |
371 | (MSIE). The reason for this is that when a server requests a client | |
372 | certificate it includes a list of CAs names which it will accept. Browsers | |
373 | will only let you select certificates from the list on the grounds that | |
374 | there is little point presenting a certificate which the server will | |
375 | reject. | |
376 | ||
377 | The solution is to add the relevant CA certificate to your servers "trusted | |
e3fefbfd | 378 | CA list". How you do this depends on the server software in uses. You can |
1a7b2d33 DSH |
379 | print out the servers list of acceptable CAs using the OpenSSL s_client tool: |
380 | ||
381 | openssl s_client -connect www.some.host:443 -prexit | |
382 | ||
959f67d6 | 383 | If your server only requests certificates on certain URLs then you may need |
1a7b2d33 DSH |
384 | to manually issue an HTTP GET command to get the list when s_client connects: |
385 | ||
386 | GET /some/page/needing/a/certificate.html | |
387 | ||
388 | If your CA does not appear in the list then this confirms the problem. | |
389 | ||
390 | ||
391 | * Why does my browser give a warning about a mismatched hostname? | |
392 | ||
393 | Browsers expect the server's hostname to match the value in the commonName | |
394 | (CN) field of the certificate. If it does not then you get a warning. | |
395 | ||
396 | ||
0b33bc6b DSH |
397 | * How do I install a CA certificate into a browser? |
398 | ||
399 | The usual way is to send the DER encoded certificate to the browser as | |
400 | MIME type application/x-x509-ca-cert, for example by clicking on an appropriate | |
401 | link. On MSIE certain extensions such as .der or .cacert may also work, or you | |
402 | can import the certificate using the certificate import wizard. | |
403 | ||
404 | You can convert a certificate to DER form using the command: | |
405 | ||
406 | openssl x509 -in ca.pem -outform DER -out ca.der | |
407 | ||
408 | Occasionally someone suggests using a command such as: | |
409 | ||
410 | openssl pkcs12 -export -out cacert.p12 -in cacert.pem -inkey cakey.pem | |
411 | ||
412 | DO NOT DO THIS! This command will give away your CAs private key and | |
413 | reduces its security to zero: allowing anyone to forge certificates in | |
414 | whatever name they choose. | |
415 | ||
17e2c77a LJ |
416 | * Why is OpenSSL x509 DN output not conformant to RFC2253? |
417 | ||
418 | The ways to print out the oneline format of the DN (Distinguished Name) have | |
419 | been extended in version 0.9.7 of OpenSSL. Using the new X509_NAME_print_ex() | |
420 | interface, the "-nameopt" option could be introduded. See the manual | |
421 | page of the "openssl x509" commandline tool for details. The old behaviour | |
422 | has however been left as default for the sake of compatibility. | |
0b33bc6b | 423 | |
09b6c2ef DSH |
424 | * What is a "128 bit certificate"? Can I create one with OpenSSL? |
425 | ||
426 | The term "128 bit certificate" is a highly misleading marketing term. It does | |
427 | *not* refer to the size of the public key in the certificate! A certificate | |
428 | containing a 128 bit RSA key would have negligible security. | |
429 | ||
430 | There were various other names such as "magic certificates", "SGC | |
431 | certificates", "step up certificates" etc. | |
432 | ||
433 | You can't generally create such a certificate using OpenSSL but there is no | |
434 | need to any more. Nowadays web browsers using unrestricted strong encryption | |
435 | are generally available. | |
436 | ||
f7a3296d | 437 | When there were tight restrictions on the export of strong encryption |
09b6c2ef DSH |
438 | software from the US only weak encryption algorithms could be freely exported |
439 | (initially 40 bit and then 56 bit). It was widely recognised that this was | |
f7a3296d | 440 | inadequate. A relaxation of the rules allowed the use of strong encryption but |
09b6c2ef DSH |
441 | only to an authorised server. |
442 | ||
443 | Two slighly different techniques were developed to support this, one used by | |
444 | Netscape was called "step up", the other used by MSIE was called "Server Gated | |
445 | Cryptography" (SGC). When a browser initially connected to a server it would | |
446 | check to see if the certificate contained certain extensions and was issued by | |
447 | an authorised authority. If these test succeeded it would reconnect using | |
448 | strong encryption. | |
449 | ||
450 | Only certain (initially one) certificate authorities could issue the | |
451 | certificates and they generally cost more than ordinary certificates. | |
452 | ||
453 | Although OpenSSL can create certificates containing the appropriate extensions | |
454 | the certificate would not come from a permitted authority and so would not | |
455 | be recognized. | |
456 | ||
457 | The export laws were later changed to allow almost unrestricted use of strong | |
458 | encryption so these certificates are now obsolete. | |
459 | ||
460 | ||
1c17d91c | 461 | * Why does OpenSSL set the authority key identifier (AKID) extension incorrectly? |
a070f0da DSH |
462 | |
463 | It doesn't: this extension is often the cause of confusion. | |
464 | ||
246e0931 | 465 | Consider a certificate chain A->B->C so that A signs B and B signs C. Suppose |
a070f0da DSH |
466 | certificate C contains AKID. |
467 | ||
468 | The purpose of this extension is to identify the authority certificate B. This | |
469 | can be done either by including the subject key identifier of B or its issuer | |
470 | name and serial number. | |
471 | ||
472 | In this latter case because it is identifying certifcate B it must contain the | |
473 | issuer name and serial number of B. | |
474 | ||
1c17d91c | 475 | It is often wrongly assumed that it should contain the subject name of B. If it |
a070f0da DSH |
476 | did this would be redundant information because it would duplicate the issuer |
477 | name of C. | |
478 | ||
479 | ||
d18ef847 LJ |
480 | * How can I set up a bundle of commercial root CA certificates? |
481 | ||
482 | The OpenSSL software is shipped without any root CA certificate as the | |
483 | OpenSSL project does not have any policy on including or excluding | |
484 | any specific CA and does not intend to set up such a policy. Deciding | |
485 | about which CAs to support is up to application developers or | |
486 | administrators. | |
487 | ||
488 | Other projects do have other policies so you can for example extract the CA | |
489 | bundle used by Mozilla and/or modssl as described in this article: | |
490 | ||
1676bec9 | 491 | <URL: http://www.mail-archive.com/modssl-users@modssl.org/msg16980.html> |
d18ef847 LJ |
492 | |
493 | ||
0ae485dc RL |
494 | [BUILD] ======================================================================= |
495 | ||
49976df5 UM |
496 | * Why does the linker complain about undefined symbols? |
497 | ||
cacbb51e | 498 | Maybe the compilation was interrupted, and make doesn't notice that |
49976df5 UM |
499 | something is missing. Run "make clean; make". |
500 | ||
501 | If you used ./Configure instead of ./config, make sure that you | |
502 | selected the right target. File formats may differ slightly between | |
503 | OS versions (for example sparcv8/sparcv9, or a.out/elf). | |
504 | ||
0816bc22 UM |
505 | In case you get errors about the following symbols, use the config |
506 | option "no-asm", as described in INSTALL: | |
507 | ||
508 | BF_cbc_encrypt, BF_decrypt, BF_encrypt, CAST_cbc_encrypt, | |
509 | CAST_decrypt, CAST_encrypt, RC4, RC5_32_cbc_encrypt, RC5_32_decrypt, | |
510 | RC5_32_encrypt, bn_add_words, bn_div_words, bn_mul_add_words, | |
511 | bn_mul_comba4, bn_mul_comba8, bn_mul_words, bn_sqr_comba4, | |
512 | bn_sqr_comba8, bn_sqr_words, bn_sub_words, des_decrypt3, | |
513 | des_ede3_cbc_encrypt, des_encrypt, des_encrypt2, des_encrypt3, | |
514 | des_ncbc_encrypt, md5_block_asm_host_order, sha1_block_asm_data_order | |
515 | ||
569be071 | 516 | If none of these helps, you may want to try using the current snapshot. |
49976df5 UM |
517 | If the problem persists, please submit a bug report. |
518 | ||
519 | ||
0ae485dc | 520 | * Why does the OpenSSL test fail with "bc: command not found"? |
2b670ea2 | 521 | |
0ae485dc RL |
522 | You didn't install "bc", the Unix calculator. If you want to run the |
523 | tests, get GNU bc from ftp://ftp.gnu.org or from your OS distributor. | |
2b670ea2 | 524 | |
2b670ea2 | 525 | |
a6ed5dd6 | 526 | * Why does the OpenSSL test fail with "bc: 1 no implemented"? |
0ae485dc | 527 | |
1417f2dc RL |
528 | On some SCO installations or versions, bc has a bug that gets triggered |
529 | when you run the test suite (using "make test"). The message returned is | |
a6ed5dd6 | 530 | "bc: 1 not implemented". |
1417f2dc RL |
531 | |
532 | The best way to deal with this is to find another implementation of bc | |
1676bec9 | 533 | and compile/install it. GNU bc (see <URL: http://www.gnu.org/software/software.html> |
1417f2dc | 534 | for download instructions) can be safely used, for example. |
f742e497 RL |
535 | |
536 | ||
537 | * Why does the OpenSSL test fail with "bc: stack empty"? | |
538 | ||
539 | On some DG/ux versions, bc seems to have a too small stack for calculations | |
540 | that the OpenSSL bntest throws at it. This gets triggered when you run the | |
541 | test suite (using "make test"). The message returned is "bc: stack empty". | |
542 | ||
543 | The best way to deal with this is to find another implementation of bc | |
1676bec9 | 544 | and compile/install it. GNU bc (see <URL: http://www.gnu.org/software/software.html> |
f742e497 | 545 | for download instructions) can be safely used, for example. |
0ae485dc RL |
546 | |
547 | ||
6bc847e4 | 548 | * Why does the OpenSSL compilation fail on Alpha Tru64 Unix? |
0ae485dc | 549 | |
6bc847e4 | 550 | On some Alpha installations running Tru64 Unix and Compaq C, the compilation |
0ae485dc RL |
551 | of crypto/sha/sha_dgst.c fails with the message 'Fatal: Insufficient virtual |
552 | memory to continue compilation.' As far as the tests have shown, this may be | |
553 | a compiler bug. What happens is that it eats up a lot of resident memory | |
554 | to build something, probably a table. The problem is clearly in the | |
555 | optimization code, because if one eliminates optimization completely (-O0), | |
556 | the compilation goes through (and the compiler consumes about 2MB of resident | |
557 | memory instead of 240MB or whatever one's limit is currently). | |
558 | ||
559 | There are three options to solve this problem: | |
560 | ||
561 | 1. set your current data segment size soft limit higher. Experience shows | |
562 | that about 241000 kbytes seems to be enough on an AlphaServer DS10. You do | |
563 | this with the command 'ulimit -Sd nnnnnn', where 'nnnnnn' is the number of | |
564 | kbytes to set the limit to. | |
565 | ||
566 | 2. If you have a hard limit that is lower than what you need and you can't | |
567 | get it changed, you can compile all of OpenSSL with -O0 as optimization | |
568 | level. This is however not a very nice thing to do for those who expect to | |
569 | get the best result from OpenSSL. A bit more complicated solution is the | |
570 | following: | |
571 | ||
572 | ----- snip:start ----- | |
573 | make DIRS=crypto SDIRS=sha "`grep '^CFLAG=' Makefile.ssl | \ | |
574 | sed -e 's/ -O[0-9] / -O0 /'`" | |
575 | rm `ls crypto/*.o crypto/sha/*.o | grep -v 'sha_dgst\.o'` | |
576 | make | |
577 | ----- snip:end ----- | |
578 | ||
579 | This will only compile sha_dgst.c with -O0, the rest with the optimization | |
580 | level chosen by the configuration process. When the above is done, do the | |
581 | test and installation and you're set. | |
582 | ||
d9248e57 AP |
583 | 3. Reconfigure the toolkit with no-sha0 option to leave out SHA0. It |
584 | should not be used and is not used in SSL/TLS nor any other recognized | |
585 | protocol in either case. | |
586 | ||
0ae485dc RL |
587 | |
588 | * Why does the OpenSSL compilation fail with "ar: command not found"? | |
589 | ||
590 | Getting this message is quite usual on Solaris 2, because Sun has hidden | |
591 | away 'ar' and other development commands in directories that aren't in | |
592 | $PATH by default. One of those directories is '/usr/ccs/bin'. The | |
593 | quickest way to fix this is to do the following (it assumes you use sh | |
594 | or any sh-compatible shell): | |
595 | ||
596 | ----- snip:start ----- | |
597 | PATH=${PATH}:/usr/ccs/bin; export PATH | |
598 | ----- snip:end ----- | |
599 | ||
600 | and then redo the compilation. What you should really do is make sure | |
601 | '/usr/ccs/bin' is permanently in your $PATH, for example through your | |
602 | '.profile' (again, assuming you use a sh-compatible shell). | |
603 | ||
604 | ||
605 | * Why does the OpenSSL compilation fail on Win32 with VC++? | |
606 | ||
607 | Sometimes, you may get reports from VC++ command line (cl) that it | |
608 | can't find standard include files like stdio.h and other weirdnesses. | |
609 | One possible cause is that the environment isn't correctly set up. | |
3d6a84c4 RL |
610 | To solve that problem for VC++ versions up to 6, one should run |
611 | VCVARS32.BAT which is found in the 'bin' subdirectory of the VC++ | |
612 | installation directory (somewhere under 'Program Files'). For VC++ | |
613 | version 7 (and up?), which is also called VS.NET, the file is called | |
614 | VSVARS32.BAT instead. | |
615 | This needs to be done prior to running NMAKE, and the changes are only | |
616 | valid for the current DOS session. | |
0ae485dc RL |
617 | |
618 | ||
c4da6dd3 LJ |
619 | * What is special about OpenSSL on Redhat? |
620 | ||
876811e2 LJ |
621 | Red Hat Linux (release 7.0 and later) include a preinstalled limited |
622 | version of OpenSSL. For patent reasons, support for IDEA, RC5 and MDC2 | |
623 | is disabled in this version. The same may apply to other Linux distributions. | |
624 | Users may therefore wish to install more or all of the features left out. | |
c4da6dd3 LJ |
625 | |
626 | To do this you MUST ensure that you do not overwrite the openssl that is in | |
627 | /usr/bin on your Red Hat machine. Several packages depend on this file, | |
628 | including sendmail and ssh. /usr/local/bin is a good alternative choice. The | |
629 | libraries that come with Red Hat 7.0 onwards have different names and so are | |
630 | not affected. (eg For Red Hat 7.2 they are /lib/libssl.so.0.9.6b and | |
631 | /lib/libcrypto.so.0.9.6b with symlinks /lib/libssl.so.2 and | |
632 | /lib/libcrypto.so.2 respectively). | |
633 | ||
634 | Please note that we have been advised by Red Hat attempting to recompile the | |
635 | openssl rpm with all the cryptography enabled will not work. All other | |
636 | packages depend on the original Red Hat supplied openssl package. It is also | |
637 | worth noting that due to the way Red Hat supplies its packages, updates to | |
638 | openssl on each distribution never change the package version, only the | |
639 | build number. For example, on Red Hat 7.1, the latest openssl package has | |
640 | version number 0.9.6 and build number 9 even though it contains all the | |
641 | relevant updates in packages up to and including 0.9.6b. | |
642 | ||
643 | A possible way around this is to persuade Red Hat to produce a non-US | |
644 | version of Red Hat Linux. | |
645 | ||
876811e2 LJ |
646 | FYI: Patent numbers and expiry dates of US patents: |
647 | MDC-2: 4,908,861 13/03/2007 | |
648 | IDEA: 5,214,703 25/05/2010 | |
649 | RC5: 5,724,428 03/03/2015 | |
650 | ||
311e2099 RL |
651 | |
652 | * Why does the OpenSSL compilation fail on MacOS X? | |
653 | ||
654 | If the failure happens when trying to build the "openssl" binary, with | |
655 | a large number of undefined symbols, it's very probable that you have | |
656 | OpenSSL 0.9.6b delivered with the operating system (you can find out by | |
657 | running '/usr/bin/openssl version') and that you were trying to build | |
658 | OpenSSL 0.9.7 or newer. The problem is that the loader ('ld') in | |
659 | MacOS X has a misfeature that's quite difficult to go around. | |
660 | Look in the file PROBLEMS for a more detailed explanation and for possible | |
661 | solutions. | |
662 | ||
663 | ||
664 | * Why does the OpenSSL test suite fail on MacOS X? | |
665 | ||
666 | If the failure happens when running 'make test' and the RC4 test fails, | |
667 | it's very probable that you have OpenSSL 0.9.6b delivered with the | |
668 | operating system (you can find out by running '/usr/bin/openssl version') | |
669 | and that you were trying to build OpenSSL 0.9.6d. The problem is that | |
670 | the loader ('ld') in MacOS X has a misfeature that's quite difficult to | |
671 | go around and has linked the programs "openssl" and the test programs | |
672 | with /usr/lib/libcrypto.dylib and /usr/lib/libssl.dylib instead of the | |
673 | libraries you just built. | |
674 | Look in the file PROBLEMS for a more detailed explanation and for possible | |
675 | solutions. | |
676 | ||
26a60b2e | 677 | * Why does the OpenSSL test suite fail in BN_sqr test [on a 64-bit platform]? |
e0b2073f AP |
678 | |
679 | Failure in BN_sqr test is most likely caused by a failure to configure the | |
26a60b2e AP |
680 | toolkit for current platform or lack of support for the platform in question. |
681 | Run './config -t' and './apps/openssl version -p'. Do these platform | |
682 | identifiers match? If they don't, then you most likely failed to run | |
683 | ./config and you're hereby advised to do so before filing a bug report. | |
684 | If ./config itself fails to run, then it's most likely problem with your | |
685 | local environment and you should turn to your system administrator (or | |
76a03d56 AP |
686 | similar). If identifiers match (and/or no alternative identifier is |
687 | suggested by ./config script), then the platform is unsupported. There might | |
688 | or might not be a workaround. Most notably on SPARC64 platforms with GNU | |
689 | C compiler you should be able to produce a working build by running | |
690 | './config -m32'. I understand that -m32 might not be what you want/need, | |
85f258d1 AP |
691 | but the build should be operational. For further details turn to |
692 | <openssl-dev@openssl.org>. | |
693 | ||
75c40285 | 694 | * Why does OpenBSD-i386 build fail on des-586.s with "Unimplemented segment type"? |
85f258d1 | 695 | |
75c40285 AP |
696 | As of 0.9.7 assembler routines were overhauled for position independence |
697 | of the machine code, which is essential for shared library support. For | |
698 | some reason OpenBSD is equipped with an out-of-date GNU assembler which | |
699 | finds the new code offensive. To work around the problem, configure with | |
0382c95e AP |
700 | no-asm (and sacrifice a great deal of performance) or patch your assembler |
701 | according to <URL: http://www.openssl.org/~appro/gas-1.92.3.OpenBSD.patch>. | |
75c40285 | 702 | For your convenience a pre-compiled replacement binary is provided at |
1a6356b2 AP |
703 | <URL: http://www.openssl.org/~appro/gas-1.92.3.static.aout.bin>. |
704 | Reportedly elder *BSD a.out platforms also suffer from this problem and | |
705 | remedy should be same. Provided binary is statically linked and should be | |
706 | working across wider range of *BSD branches, not just OpenBSD. | |
e0b2073f | 707 | |
851e31ff AP |
708 | * Why does the OpenSSL test suite fail in sha512t on x86 CPU? |
709 | ||
710 | If the test program in question fails withs SIGILL, Illegal Instruction | |
711 | exception, then you more than likely to run SSE2-capable CPU, such as | |
712 | Intel P4, under control of kernel which does not support SSE2 | |
713 | instruction extentions. See accompanying INSTALL file and | |
714 | OPENSSL_ia32cap(3) documentation page for further information. | |
715 | ||
4b559868 AP |
716 | * Why does compiler fail to compile sha512.c? |
717 | ||
718 | OpenSSL SHA-512 implementation depends on compiler support for 64-bit | |
719 | integer type. Few elder compilers [ULTRIX cc, SCO compiler to mention a | |
720 | couple] lack support for this and therefore are incapable of compiling | |
721 | the module in question. The recommendation is to disable SHA-512 by | |
722 | adding no-sha512 to ./config [or ./Configure] command line. Another | |
723 | possible alternative might be to switch to GCC. | |
724 | ||
65613f23 AP |
725 | * Test suite still fails, what to do? |
726 | ||
727 | Another common reason for failure to complete some particular test is | |
728 | simply bad code generated by a buggy component in toolchain or deficiency | |
729 | in run-time environment. There are few cases documented in PROBLEMS file, | |
730 | consult it for possible workaround before you beat the drum. Even if you | |
731 | don't find solution or even mention there, do reserve for possibility of | |
732 | a compiler bug. Compiler bugs might appear in rather bizarre ways, they | |
733 | never make sense, and tend to emerge when you least expect them. In order | |
734 | to identify one, drop optimization level, e.g. by editing CFLAG line in | |
735 | top-level Makefile, recompile and re-run the test. | |
736 | ||
c25a0aae DSH |
737 | * I think I've found a bug, what should I do? |
738 | ||
739 | If you are a new user then it is quite likely you haven't found a bug and | |
740 | something is happening you aren't familiar with. Check this FAQ, the associated | |
741 | documentation and the mailing lists for similar queries. If you are still | |
742 | unsure whether it is a bug or not submit a query to the openssl-users mailing | |
743 | list. | |
744 | ||
4b0771c1 | 745 | |
c25a0aae DSH |
746 | * I'm SURE I've found a bug, how do I report it? |
747 | ||
748 | Bug reports with no security implications should be sent to the request | |
c17171c6 | 749 | tracker. This can be done by mailing the report to <rt@openssl.org> (or its |
1676bec9 DSH |
750 | alias <openssl-bugs@openssl.org>), please note that messages sent to the |
751 | request tracker also appear in the public openssl-dev mailing list. | |
c25a0aae DSH |
752 | |
753 | The report should be in plain text. Any patches should be sent as | |
754 | plain text attachments because some mailers corrupt patches sent inline. | |
1676bec9 | 755 | If your issue affects multiple versions of OpenSSL check any patches apply |
c25a0aae DSH |
756 | cleanly and, if possible include patches to each affected version. |
757 | ||
758 | The report should be given a meaningful subject line briefly summarising the | |
759 | issue. Just "bug in OpenSSL" or "bug in OpenSSL 0.9.8n" is not very helpful. | |
760 | ||
761 | By sending reports to the request tracker the bug can then be given a priority | |
762 | and assigned to the appropriate maintainer. The history of discussions can be | |
763 | accessed and if the issue has been addressed or a reason why not. If patches | |
1676bec9 | 764 | are only sent to openssl-dev they can be mislaid if a team member has to |
c25a0aae DSH |
765 | wade through months of old messages to review the discussion. |
766 | ||
1676bec9 | 767 | See also <URL: http://www.openssl.org/support/rt.html> |
c25a0aae | 768 | |
4b0771c1 | 769 | |
c25a0aae DSH |
770 | * I've found a security issue, how do I report it? |
771 | ||
772 | If you think your bug has security implications then please send it to | |
773 | openssl-security@openssl.org if you don't get a prompt reply at least | |
774 | acknowledging receipt then resend or mail it directly to one of the | |
1676bec9 | 775 | more active team members (e.g. Steve). |
c25a0aae | 776 | |
0ae485dc RL |
777 | [PROG] ======================================================================== |
778 | ||
779 | * Is OpenSSL thread-safe? | |
780 | ||
781 | Yes (with limitations: an SSL connection may not concurrently be used | |
782 | by multiple threads). On Windows and many Unix systems, OpenSSL | |
783 | automatically uses the multi-threaded versions of the standard | |
784 | libraries. If your platform is not one of these, consult the INSTALL | |
785 | file. | |
786 | ||
787 | Multi-threaded applications must provide two callback functions to | |
48fc582f | 788 | OpenSSL by calling CRYPTO_set_locking_callback() and |
ab9c689a | 789 | CRYPTO_set_id_callback(), for all versions of OpenSSL up to and |
8decc967 | 790 | including 0.9.8[abc...]. As of version 1.0.0, CRYPTO_set_id_callback() |
ab9c689a GT |
791 | and associated APIs are deprecated by CRYPTO_THREADID_set_callback() |
792 | and friends. This is described in the threads(3) manpage. | |
afee764c | 793 | |
46e80a30 DSH |
794 | * I've compiled a program under Windows and it crashes: why? |
795 | ||
a542db90 RL |
796 | This is usually because you've missed the comment in INSTALL.W32. |
797 | Your application must link against the same version of the Win32 | |
798 | C-Runtime against which your openssl libraries were linked. The | |
799 | default version for OpenSSL is /MD - "Multithreaded DLL". | |
800 | ||
801 | If you are using Microsoft Visual C++'s IDE (Visual Studio), in | |
802 | many cases, your new project most likely defaulted to "Debug | |
803 | Singlethreaded" - /ML. This is NOT interchangeable with /MD and your | |
804 | program will crash, typically on the first BIO related read or write | |
805 | operation. | |
806 | ||
807 | For each of the six possible link stage configurations within Win32, | |
808 | your application must link against the same by which OpenSSL was | |
809 | built. If you are using MS Visual C++ (Studio) this can be changed | |
810 | by: | |
811 | ||
65613f23 AP |
812 | 1. Select Settings... from the Project Menu. |
813 | 2. Select the C/C++ Tab. | |
814 | 3. Select "Code Generation from the "Category" drop down list box | |
815 | 4. Select the Appropriate library (see table below) from the "Use | |
a542db90 RL |
816 | run-time library" drop down list box. Perform this step for both |
817 | your debug and release versions of your application (look at the | |
818 | top left of the settings panel to change between the two) | |
819 | ||
820 | Single Threaded /ML - MS VC++ often defaults to | |
821 | this for the release | |
822 | version of a new project. | |
823 | Debug Single Threaded /MLd - MS VC++ often defaults to | |
824 | this for the debug version | |
825 | of a new project. | |
826 | Multithreaded /MT | |
827 | Debug Multithreaded /MTd | |
828 | Multithreaded DLL /MD - OpenSSL defaults to this. | |
829 | Debug Multithreaded DLL /MDd | |
830 | ||
831 | Note that debug and release libraries are NOT interchangeable. If you | |
832 | built OpenSSL with /MD your application must use /MD and cannot use /MDd. | |
46e80a30 | 833 | |
788e67e2 | 834 | As per 0.9.8 the above limitation is eliminated for .DLLs. OpenSSL |
2c730f6f | 835 | .DLLs compiled with some specific run-time option [we insist on the |
788e67e2 AP |
836 | default /MD] can be deployed with application compiled with different |
837 | option or even different compiler. But there is a catch! Instead of | |
838 | re-compiling OpenSSL toolkit, as you would have to with prior versions, | |
839 | you have to compile small C snippet with compiler and/or options of | |
840 | your choice. The snippet gets installed as | |
841 | <install-root>/include/openssl/applink.c and should be either added to | |
2c730f6f AP |
842 | your application project or simply #include-d in one [and only one] |
843 | of your application source files. Failure to link this shim module | |
844 | into your application manifests itself as fatal "no OPENSSL_Applink" | |
845 | run-time error. An explicit reminder is due that in this situation | |
846 | [mixing compiler options] it is as important to add CRYPTO_malloc_init | |
847 | prior first call to OpenSSL. | |
46e80a30 | 848 | |
c5a3b7e7 DSH |
849 | * How do I read or write a DER encoded buffer using the ASN1 functions? |
850 | ||
851 | You have two options. You can either use a memory BIO in conjunction | |
ec7c9ee8 DSH |
852 | with the i2d_*_bio() or d2i_*_bio() functions or you can use the |
853 | i2d_*(), d2i_*() functions directly. Since these are often the | |
c5a3b7e7 DSH |
854 | cause of grief here are some code fragments using PKCS7 as an example: |
855 | ||
ec7c9ee8 DSH |
856 | unsigned char *buf, *p; |
857 | int len; | |
c5a3b7e7 | 858 | |
ec7c9ee8 DSH |
859 | len = i2d_PKCS7(p7, NULL); |
860 | buf = OPENSSL_malloc(len); /* or Malloc, error checking omitted */ | |
861 | p = buf; | |
862 | i2d_PKCS7(p7, &p); | |
c5a3b7e7 DSH |
863 | |
864 | At this point buf contains the len bytes of the DER encoding of | |
865 | p7. | |
866 | ||
867 | The opposite assumes we already have len bytes in buf: | |
868 | ||
ec7c9ee8 DSH |
869 | unsigned char *p; |
870 | p = buf; | |
871 | p7 = d2i_PKCS7(NULL, &p, len); | |
c5a3b7e7 | 872 | |
2527b94f | 873 | At this point p7 contains a valid PKCS7 structure or NULL if an error |
c5a3b7e7 DSH |
874 | occurred. If an error occurred ERR_print_errors(bio) should give more |
875 | information. | |
876 | ||
877 | The reason for the temporary variable 'p' is that the ASN1 functions | |
878 | increment the passed pointer so it is ready to read or write the next | |
879 | structure. This is often a cause of problems: without the temporary | |
880 | variable the buffer pointer is changed to point just after the data | |
881 | that has been read or written. This may well be uninitialized data | |
882 | and attempts to free the buffer will have unpredictable results | |
883 | because it no longer points to the same address. | |
884 | ||
2527b94f DSH |
885 | Memory allocation and encoding can also be combined in a single |
886 | operation by the ASN1 routines: | |
887 | ||
888 | unsigned char *buf = NULL; /* mandatory */ | |
889 | int len; | |
890 | len = i2d_PKCS7(p7, &buf); | |
891 | if (len < 0) | |
892 | /* Error */ | |
893 | /* Do some things with 'buf' */ | |
894 | /* Finished with buf: free it */ | |
895 | OPENSSL_free(buf); | |
896 | ||
897 | In this special case the "buf" parameter is *not* incremented, it points | |
898 | to the start of the encoding. | |
899 | ||
c5a3b7e7 | 900 | |
6ef7b78e DSH |
901 | * OpenSSL uses DER but I need BER format: does OpenSSL support BER? |
902 | ||
903 | The short answer is yes, because DER is a special case of BER and OpenSSL | |
904 | ASN1 decoders can process BER. | |
905 | ||
906 | The longer answer is that ASN1 structures can be encoded in a number of | |
907 | different ways. One set of ways is the Basic Encoding Rules (BER) with various | |
908 | permissible encodings. A restriction of BER is the Distinguished Encoding | |
909 | Rules (DER): these uniquely specify how a given structure is encoded. | |
910 | ||
911 | Therefore, because DER is a special case of BER, DER is an acceptable encoding | |
912 | for BER. | |
913 | ||
914 | ||
84b65340 DSH |
915 | * I've tried using <M_some_evil_pkcs12_macro> and I get errors why? |
916 | ||
917 | This usually happens when you try compiling something using the PKCS#12 | |
918 | macros with a C++ compiler. There is hardly ever any need to use the | |
919 | PKCS#12 macros in a program, it is much easier to parse and create | |
920 | PKCS#12 files using the PKCS12_parse() and PKCS12_create() functions | |
921 | documented in doc/openssl.txt and with examples in demos/pkcs12. The | |
922 | 'pkcs12' application has to use the macros because it prints out | |
923 | debugging information. | |
924 | ||
925 | ||
35af460f DSH |
926 | * I've called <some function> and it fails, why? |
927 | ||
02859fb7 BM |
928 | Before submitting a report or asking in one of the mailing lists, you |
929 | should try to determine the cause. In particular, you should call | |
35af460f | 930 | ERR_print_errors() or ERR_print_errors_fp() after the failed call |
02859fb7 BM |
931 | and see if the message helps. Note that the problem may occur earlier |
932 | than you think -- you should check for errors after every call where | |
933 | it is possible, otherwise the actual problem may be hidden because | |
934 | some OpenSSL functions clear the error state. | |
35af460f DSH |
935 | |
936 | ||
937 | * I just get a load of numbers for the error output, what do they mean? | |
938 | ||
939 | The actual format is described in the ERR_print_errors() manual page. | |
940 | You should call the function ERR_load_crypto_strings() before hand and | |
941 | the message will be output in text form. If you can't do this (for example | |
942 | it is a pre-compiled binary) you can use the errstr utility on the error | |
943 | code itself (the hex digits after the second colon). | |
944 | ||
945 | ||
46e80a30 DSH |
946 | * Why do I get errors about unknown algorithms? |
947 | ||
930875ef DSH |
948 | The cause is forgetting to load OpenSSL's table of algorithms with |
949 | OpenSSL_add_all_algorithms(). See the manual page for more information. This | |
950 | can cause several problems such as being unable to read in an encrypted | |
951 | PEM file, unable to decrypt a PKCS#12 file or signature failure when | |
952 | verifying certificates. | |
46e80a30 | 953 | |
e8dbc159 RL |
954 | * Why can't the OpenSSH configure script detect OpenSSL? |
955 | ||
a116afa4 LJ |
956 | Several reasons for problems with the automatic detection exist. |
957 | OpenSSH requires at least version 0.9.5a of the OpenSSL libraries. | |
958 | Sometimes the distribution has installed an older version in the system | |
959 | locations that is detected instead of a new one installed. The OpenSSL | |
960 | library might have been compiled for another CPU or another mode (32/64 bits). | |
961 | Permissions might be wrong. | |
962 | ||
963 | The general answer is to check the config.log file generated when running | |
964 | the OpenSSH configure script. It should contain the detailed information | |
965 | on why the OpenSSL library was not detected or considered incompatible. | |
31efc3a7 | 966 | |
500df82a | 967 | |
0ae485dc | 968 | * Can I use OpenSSL's SSL library with non-blocking I/O? |
bf55ece1 | 969 | |
0ae485dc | 970 | Yes; make sure to read the SSL_get_error(3) manual page! |
bf55ece1 | 971 | |
0ae485dc RL |
972 | A pitfall to avoid: Don't assume that SSL_read() will just read from |
973 | the underlying transport or that SSL_write() will just write to it -- | |
974 | it is also possible that SSL_write() cannot do any useful work until | |
975 | there is data to read, or that SSL_read() cannot do anything until it | |
976 | is possible to send data. One reason for this is that the peer may | |
977 | request a new TLS/SSL handshake at any time during the protocol, | |
978 | requiring a bi-directional message exchange; both SSL_read() and | |
979 | SSL_write() will try to continue any pending handshake. | |
bf55ece1 | 980 | |
bf55ece1 | 981 | |
19732245 LJ |
982 | * Why doesn't my server application receive a client certificate? |
983 | ||
984 | Due to the TLS protocol definition, a client will only send a certificate, | |
e3fefbfd | 985 | if explicitly asked by the server. Use the SSL_VERIFY_PEER flag of the |
19732245 LJ |
986 | SSL_CTX_set_verify() function to enable the use of client certificates. |
987 | ||
988 | ||
e1f7ea25 LJ |
989 | * Why does compilation fail due to an undefined symbol NID_uniqueIdentifier? |
990 | ||
e8233e69 LJ |
991 | For OpenSSL 0.9.7 the OID table was extended and corrected. In earlier |
992 | versions, uniqueIdentifier was incorrectly used for X.509 certificates. | |
993 | The correct name according to RFC2256 (LDAP) is x500UniqueIdentifier. | |
994 | Change your code to use the new name when compiling against OpenSSL 0.9.7. | |
e1f7ea25 LJ |
995 | |
996 | ||
6ef7b78e DSH |
997 | * I think I've detected a memory leak, is this a bug? |
998 | ||
999 | In most cases the cause of an apparent memory leak is an OpenSSL internal table | |
1000 | that is allocated when an application starts up. Since such tables do not grow | |
1001 | in size over time they are harmless. | |
1002 | ||
1003 | These internal tables can be freed up when an application closes using various | |
6141b86a RL |
1004 | functions. Currently these include following: |
1005 | ||
1006 | Thread-local cleanup functions: | |
1007 | ||
1008 | ERR_remove_state() | |
1009 | ||
1010 | Application-global cleanup functions that are aware of usage (and therefore | |
1011 | thread-safe): | |
1012 | ||
1013 | ENGINE_cleanup() and CONF_modules_unload() | |
1014 | ||
1015 | "Brutal" (thread-unsafe) Application-global cleanup functions: | |
1016 | ||
1017 | ERR_free_strings(), EVP_cleanup() and CRYPTO_cleanup_all_ex_data(). | |
6ef7b78e DSH |
1018 | |
1019 | ||
7bbce697 LJ |
1020 | * Why does Valgrind complain about the use of uninitialized data? |
1021 | ||
1022 | When OpenSSL's PRNG routines are called to generate random numbers the supplied | |
1023 | buffer contents are mixed into the entropy pool: so it technically does not | |
1024 | matter whether the buffer is initialized at this point or not. Valgrind (and | |
1025 | other test tools) will complain about this. When using Valgrind, make sure the | |
1026 | OpenSSL library has been compiled with the PURIFY macro defined (-DPURIFY) | |
1027 | to get rid of these warnings. | |
1028 | ||
1029 | ||
715020e3 DSH |
1030 | * Why doesn't a memory BIO work when a file does? |
1031 | ||
1032 | This can occur in several cases for example reading an S/MIME email message. | |
1033 | The reason is that a memory BIO can do one of two things when all the data | |
1034 | has been read from it. | |
1035 | ||
1036 | The default behaviour is to indicate that no more data is available and that | |
1037 | the call should be retried, this is to allow the application to fill up the BIO | |
1038 | again if necessary. | |
1039 | ||
1040 | Alternatively it can indicate that no more data is available and that EOF has | |
1041 | been reached. | |
1042 | ||
1043 | If a memory BIO is to behave in the same way as a file this second behaviour | |
1044 | is needed. This must be done by calling: | |
1045 | ||
1046 | BIO_set_mem_eof_return(bio, 0); | |
1047 | ||
29a1bb07 DSH |
1048 | See the manual pages for more details. |
1049 | ||
715020e3 | 1050 | |
dd57b657 DSH |
1051 | * Where are the declarations and implementations of d2i_X509() etc? |
1052 | ||
13d75246 | 1053 | These are defined and implemented by macros of the form: |
dd57b657 DSH |
1054 | |
1055 | ||
1056 | DECLARE_ASN1_FUNCTIONS(X509) and IMPLEMENT_ASN1_FUNCTIONS(X509) | |
1057 | ||
1058 | The implementation passes an ASN1 "template" defining the structure into an | |
1059 | ASN1 interpreter using generalised functions such as ASN1_item_d2i(). | |
1060 | ||
1061 | ||
0ae485dc | 1062 | =============================================================================== |