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