Import OpenSSL 0.9.8e.
[dragonfly.git] / crypto / openssl-0.9 / FAQ
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1OpenSSL - 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?
74093195 34* What is a "128 bit certificate"? Can I create one with OpenSSL?
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35
36[BUILD] Questions about building and testing OpenSSL
37
38* Why does the linker complain about undefined symbols?
39* Why does the OpenSSL test fail with "bc: command not found"?
40* Why does the OpenSSL test fail with "bc: 1 no implemented"?
41* Why does the OpenSSL test fail with "bc: stack empty"?
42* Why does the OpenSSL compilation fail on Alpha Tru64 Unix?
43* Why does the OpenSSL compilation fail with "ar: command not found"?
44* Why does the OpenSSL compilation fail on Win32 with VC++?
45* What is special about OpenSSL on Redhat?
46* Why does the OpenSSL compilation fail on MacOS X?
47* Why does the OpenSSL test suite fail on MacOS X?
48* Why does the OpenSSL test suite fail in BN_sqr test [on a 64-bit platform]?
49* Why does OpenBSD-i386 build fail on des-586.s with "Unimplemented segment type"?
50* Why does the OpenSSL test suite fail in sha512t on x86 CPU?
51* Why does compiler fail to compile sha512.c?
74093195 52* Test suite still fails, what to do?
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53
54[PROG] Questions about programming with OpenSSL
55
56* Is OpenSSL thread-safe?
57* I've compiled a program under Windows and it crashes: why?
58* How do I read or write a DER encoded buffer using the ASN1 functions?
59* OpenSSL uses DER but I need BER format: does OpenSSL support BER?
60* I've tried using <M_some_evil_pkcs12_macro> and I get errors why?
61* I've called <some function> and it fails, why?
62* I just get a load of numbers for the error output, what do they mean?
63* Why do I get errors about unknown algorithms?
64* Why can't the OpenSSH configure script detect OpenSSL?
65* Can I use OpenSSL's SSL library with non-blocking I/O?
66* Why doesn't my server application receive a client certificate?
67* Why does compilation fail due to an undefined symbol NID_uniqueIdentifier?
68* I think I've detected a memory leak, is this a bug?
69
70===============================================================================
71
72[MISC] ========================================================================
73
74* Which is the current version of OpenSSL?
75
76The current version is available from <URL: http://www.openssl.org>.
e40c9513 77OpenSSL 0.9.8e was released on February 23rd, 2007.
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78
79In addition to the current stable release, you can also access daily
80snapshots of the OpenSSL development version at <URL:
81ftp://ftp.openssl.org/snapshot/>, or get it by anonymous CVS access.
82
83
84* Where is the documentation?
85
86OpenSSL is a library that provides cryptographic functionality to
87applications such as secure web servers. Be sure to read the
88documentation of the application you want to use. The INSTALL file
89explains how to install this library.
90
91OpenSSL includes a command line utility that can be used to perform a
92variety of cryptographic functions. It is described in the openssl(1)
93manpage. Documentation for developers is currently being written. A
94few manual pages already are available; overviews over libcrypto and
95libssl are given in the crypto(3) and ssl(3) manpages.
96
97The OpenSSL manpages are installed in /usr/local/ssl/man/ (or a
98different directory if you specified one as described in INSTALL).
99In addition, you can read the most current versions at
100<URL: http://www.openssl.org/docs/>.
101
102For information on parts of libcrypto that are not yet documented, you
103might want to read Ariel Glenn's documentation on SSLeay 0.9, OpenSSL's
104predecessor, at <URL: http://www.columbia.edu/~ariel/ssleay/>. Much
105of this still applies to OpenSSL.
106
107There is some documentation about certificate extensions and PKCS#12
108in doc/openssl.txt
109
110The original SSLeay documentation is included in OpenSSL as
111doc/ssleay.txt. It may be useful when none of the other resources
112help, but please note that it reflects the obsolete version SSLeay
1130.6.6.
114
115
116* How can I contact the OpenSSL developers?
117
118The README file describes how to submit bug reports and patches to
119OpenSSL. Information on the OpenSSL mailing lists is available from
120<URL: http://www.openssl.org>.
121
122
123* Where can I get a compiled version of OpenSSL?
124
125You can finder pointers to binary distributions in
126http://www.openssl.org/related/binaries.html .
127
128Some applications that use OpenSSL are distributed in binary form.
129When using such an application, you don't need to install OpenSSL
130yourself; the application will include the required parts (e.g. DLLs).
131
132If you want to build OpenSSL on a Windows system and you don't have
133a C compiler, read the "Mingw32" section of INSTALL.W32 for information
134on how to obtain and install the free GNU C compiler.
135
136A number of Linux and *BSD distributions include OpenSSL.
137
138
139* Why aren't tools like 'autoconf' and 'libtool' used?
140
141autoconf will probably be used in future OpenSSL versions. If it was
142less Unix-centric, it might have been used much earlier.
143
144* What is an 'engine' version?
145
146With version 0.9.6 OpenSSL was extended to interface to external crypto
147hardware. This was realized in a special release '0.9.6-engine'. With
148version 0.9.7 the changes were merged into the main development line,
149so that the special release is no longer necessary.
150
151* How do I check the authenticity of the OpenSSL distribution?
152
153We provide MD5 digests and ASC signatures of each tarball.
154Use MD5 to check that a tarball from a mirror site is identical:
155
156 md5sum TARBALL | awk '{print $1;}' | cmp - TARBALL.md5
157
158You can check authenticity using pgp or gpg. You need the OpenSSL team
159member public key used to sign it (download it from a key server, see a
160list of keys at <URL: http://www.openssl.org/about/>). Then
161just do:
162
163 pgp TARBALL.asc
164
165[LEGAL] =======================================================================
166
167* Do I need patent licenses to use OpenSSL?
168
169The patents section of the README file lists patents that may apply to
170you if you want to use OpenSSL. For information on intellectual
171property rights, please consult a lawyer. The OpenSSL team does not
172offer legal advice.
173
174You can configure OpenSSL so as not to use IDEA, MDC2 and RC5 by using
175 ./config no-idea no-mdc2 no-rc5
176
177
178* Can I use OpenSSL with GPL software?
179
180On many systems including the major Linux and BSD distributions, yes (the
181GPL does not place restrictions on using libraries that are part of the
182normal operating system distribution).
183
184On other systems, the situation is less clear. Some GPL software copyright
185holders claim that you infringe on their rights if you use OpenSSL with
186their software on operating systems that don't normally include OpenSSL.
187
188If you develop open source software that uses OpenSSL, you may find it
189useful to choose an other license than the GPL, or state explicitly that
190"This program is released under the GPL with the additional exemption that
191compiling, linking, and/or using OpenSSL is allowed." If you are using
192GPL software developed by others, you may want to ask the copyright holder
193for permission to use their software with OpenSSL.
194
195
196[USER] ========================================================================
197
198* Why do I get a "PRNG not seeded" error message?
199
200Cryptographic software needs a source of unpredictable data to work
201correctly. Many open source operating systems provide a "randomness
202device" (/dev/urandom or /dev/random) that serves this purpose.
203All OpenSSL versions try to use /dev/urandom by default; starting with
204version 0.9.7, OpenSSL also tries /dev/random if /dev/urandom is not
205available.
206
207On other systems, applications have to call the RAND_add() or
208RAND_seed() function with appropriate data before generating keys or
209performing public key encryption. (These functions initialize the
210pseudo-random number generator, PRNG.) Some broken applications do
211not do this. As of version 0.9.5, the OpenSSL functions that need
212randomness report an error if the random number generator has not been
213seeded with at least 128 bits of randomness. If this error occurs and
214is not discussed in the documentation of the application you are
215using, please contact the author of that application; it is likely
216that it never worked correctly. OpenSSL 0.9.5 and later make the
217error visible by refusing to perform potentially insecure encryption.
218
219If you are using Solaris 8, you can add /dev/urandom and /dev/random
220devices by installing patch 112438 (Sparc) or 112439 (x86), which are
221available via the Patchfinder at <URL: http://sunsolve.sun.com>
222(Solaris 9 includes these devices by default). For /dev/random support
223for earlier Solaris versions, see Sun's statement at
224<URL: http://sunsolve.sun.com/pub-cgi/retrieve.pl?doc=fsrdb/27606&zone_32=SUNWski>
225(the SUNWski package is available in patch 105710).
226
227On systems without /dev/urandom and /dev/random, it is a good idea to
228use the Entropy Gathering Demon (EGD); see the RAND_egd() manpage for
229details. Starting with version 0.9.7, OpenSSL will automatically look
230for an EGD socket at /var/run/egd-pool, /dev/egd-pool, /etc/egd-pool and
231/etc/entropy.
232
233Most components of the openssl command line utility automatically try
234to seed the random number generator from a file. The name of the
235default seeding file is determined as follows: If environment variable
236RANDFILE is set, then it names the seeding file. Otherwise if
237environment variable HOME is set, then the seeding file is $HOME/.rnd.
238If neither RANDFILE nor HOME is set, versions up to OpenSSL 0.9.6 will
239use file .rnd in the current directory while OpenSSL 0.9.6a uses no
240default seeding file at all. OpenSSL 0.9.6b and later will behave
241similarly to 0.9.6a, but will use a default of "C:\" for HOME on
242Windows systems if the environment variable has not been set.
243
244If the default seeding file does not exist or is too short, the "PRNG
245not seeded" error message may occur.
246
247The openssl command line utility will write back a new state to the
248default seeding file (and create this file if necessary) unless
249there was no sufficient seeding.
250
251Pointing $RANDFILE to an Entropy Gathering Daemon socket does not work.
252Use the "-rand" option of the OpenSSL command line tools instead.
253The $RANDFILE environment variable and $HOME/.rnd are only used by the
254OpenSSL command line tools. Applications using the OpenSSL library
255provide their own configuration options to specify the entropy source,
256please check out the documentation coming the with application.
257
258
259* Why do I get an "unable to write 'random state'" error message?
260
261
262Sometimes the openssl command line utility does not abort with
263a "PRNG not seeded" error message, but complains that it is
264"unable to write 'random state'". This message refers to the
265default seeding file (see previous answer). A possible reason
266is that no default filename is known because neither RANDFILE
267nor HOME is set. (Versions up to 0.9.6 used file ".rnd" in the
268current directory in this case, but this has changed with 0.9.6a.)
269
270
271* How do I create certificates or certificate requests?
272
273Check out the CA.pl(1) manual page. This provides a simple wrapper round
274the 'req', 'verify', 'ca' and 'pkcs12' utilities. For finer control check
275out the manual pages for the individual utilities and the certificate
276extensions documentation (currently in doc/openssl.txt).
277
278
279* Why can't I create certificate requests?
280
281You typically get the error:
282
283 unable to find 'distinguished_name' in config
284 problems making Certificate Request
285
286This is because it can't find the configuration file. Check out the
287DIAGNOSTICS section of req(1) for more information.
288
289
290* Why does <SSL program> fail with a certificate verify error?
291
292This problem is usually indicated by log messages saying something like
293"unable to get local issuer certificate" or "self signed certificate".
294When a certificate is verified its root CA must be "trusted" by OpenSSL
295this typically means that the CA certificate must be placed in a directory
296or file and the relevant program configured to read it. The OpenSSL program
297'verify' behaves in a similar way and issues similar error messages: check
298the verify(1) program manual page for more information.
299
300
301* Why can I only use weak ciphers when I connect to a server using OpenSSL?
302
303This is almost certainly because you are using an old "export grade" browser
304which only supports weak encryption. Upgrade your browser to support 128 bit
305ciphers.
306
307
308* How can I create DSA certificates?
309
310Check the CA.pl(1) manual page for a DSA certificate example.
311
312
313* Why can't I make an SSL connection to a server using a DSA certificate?
314
315Typically you'll see a message saying there are no shared ciphers when
316the same setup works fine with an RSA certificate. There are two possible
317causes. The client may not support connections to DSA servers most web
318browsers (including Netscape and MSIE) only support connections to servers
319supporting RSA cipher suites. The other cause is that a set of DH parameters
320has not been supplied to the server. DH parameters can be created with the
321dhparam(1) command and loaded using the SSL_CTX_set_tmp_dh() for example:
322check the source to s_server in apps/s_server.c for an example.
323
324
325* How can I remove the passphrase on a private key?
326
327Firstly you should be really *really* sure you want to do this. Leaving
328a private key unencrypted is a major security risk. If you decide that
329you do have to do this check the EXAMPLES sections of the rsa(1) and
330dsa(1) manual pages.
331
332
333* Why can't I use OpenSSL certificates with SSL client authentication?
334
335What will typically happen is that when a server requests authentication
336it will either not include your certificate or tell you that you have
337no client certificates (Netscape) or present you with an empty list box
338(MSIE). The reason for this is that when a server requests a client
339certificate it includes a list of CAs names which it will accept. Browsers
340will only let you select certificates from the list on the grounds that
341there is little point presenting a certificate which the server will
342reject.
343
344The solution is to add the relevant CA certificate to your servers "trusted
345CA list". How you do this depends on the server software in uses. You can
346print out the servers list of acceptable CAs using the OpenSSL s_client tool:
347
348openssl s_client -connect www.some.host:443 -prexit
349
350If your server only requests certificates on certain URLs then you may need
351to manually issue an HTTP GET command to get the list when s_client connects:
352
353GET /some/page/needing/a/certificate.html
354
355If your CA does not appear in the list then this confirms the problem.
356
357
358* Why does my browser give a warning about a mismatched hostname?
359
360Browsers expect the server's hostname to match the value in the commonName
361(CN) field of the certificate. If it does not then you get a warning.
362
363
364* How do I install a CA certificate into a browser?
365
366The usual way is to send the DER encoded certificate to the browser as
367MIME type application/x-x509-ca-cert, for example by clicking on an appropriate
368link. On MSIE certain extensions such as .der or .cacert may also work, or you
369can import the certificate using the certificate import wizard.
370
371You can convert a certificate to DER form using the command:
372
373openssl x509 -in ca.pem -outform DER -out ca.der
374
375Occasionally someone suggests using a command such as:
376
377openssl pkcs12 -export -out cacert.p12 -in cacert.pem -inkey cakey.pem
378
379DO NOT DO THIS! This command will give away your CAs private key and
380reduces its security to zero: allowing anyone to forge certificates in
381whatever name they choose.
382
383* Why is OpenSSL x509 DN output not conformant to RFC2253?
384
385The ways to print out the oneline format of the DN (Distinguished Name) have
386been extended in version 0.9.7 of OpenSSL. Using the new X509_NAME_print_ex()
387interface, the "-nameopt" option could be introduded. See the manual
388page of the "openssl x509" commandline tool for details. The old behaviour
389has however been left as default for the sake of compatibility.
390
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391* What is a "128 bit certificate"? Can I create one with OpenSSL?
392
393The term "128 bit certificate" is a highly misleading marketing term. It does
394*not* refer to the size of the public key in the certificate! A certificate
395containing a 128 bit RSA key would have negligible security.
396
397There were various other names such as "magic certificates", "SGC
398certificates", "step up certificates" etc.
399
400You can't generally create such a certificate using OpenSSL but there is no
401need to any more. Nowadays web browsers using unrestricted strong encryption
402are generally available.
403
404When there were tight export restrictions on the export of strong encryption
405software from the US only weak encryption algorithms could be freely exported
406(initially 40 bit and then 56 bit). It was widely recognised that this was
407inadequate. A relaxation the rules allowed the use of strong encryption but
408only to an authorised server.
409
410Two slighly different techniques were developed to support this, one used by
411Netscape was called "step up", the other used by MSIE was called "Server Gated
412Cryptography" (SGC). When a browser initially connected to a server it would
413check to see if the certificate contained certain extensions and was issued by
414an authorised authority. If these test succeeded it would reconnect using
415strong encryption.
416
417Only certain (initially one) certificate authorities could issue the
418certificates and they generally cost more than ordinary certificates.
419
420Although OpenSSL can create certificates containing the appropriate extensions
421the certificate would not come from a permitted authority and so would not
422be recognized.
423
424The export laws were later changed to allow almost unrestricted use of strong
425encryption so these certificates are now obsolete.
426
427
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428[BUILD] =======================================================================
429
430* Why does the linker complain about undefined symbols?
431
432Maybe the compilation was interrupted, and make doesn't notice that
433something is missing. Run "make clean; make".
434
435If you used ./Configure instead of ./config, make sure that you
436selected the right target. File formats may differ slightly between
437OS versions (for example sparcv8/sparcv9, or a.out/elf).
438
439In case you get errors about the following symbols, use the config
440option "no-asm", as described in INSTALL:
441
442 BF_cbc_encrypt, BF_decrypt, BF_encrypt, CAST_cbc_encrypt,
443 CAST_decrypt, CAST_encrypt, RC4, RC5_32_cbc_encrypt, RC5_32_decrypt,
444 RC5_32_encrypt, bn_add_words, bn_div_words, bn_mul_add_words,
445 bn_mul_comba4, bn_mul_comba8, bn_mul_words, bn_sqr_comba4,
446 bn_sqr_comba8, bn_sqr_words, bn_sub_words, des_decrypt3,
447 des_ede3_cbc_encrypt, des_encrypt, des_encrypt2, des_encrypt3,
448 des_ncbc_encrypt, md5_block_asm_host_order, sha1_block_asm_data_order
449
450If none of these helps, you may want to try using the current snapshot.
451If the problem persists, please submit a bug report.
452
453
454* Why does the OpenSSL test fail with "bc: command not found"?
455
456You didn't install "bc", the Unix calculator. If you want to run the
457tests, get GNU bc from ftp://ftp.gnu.org or from your OS distributor.
458
459
460* Why does the OpenSSL test fail with "bc: 1 no implemented"?
461
462On some SCO installations or versions, bc has a bug that gets triggered
463when you run the test suite (using "make test"). The message returned is
464"bc: 1 not implemented".
465
466The best way to deal with this is to find another implementation of bc
467and compile/install it. GNU bc (see http://www.gnu.org/software/software.html
468for download instructions) can be safely used, for example.
469
470
471* Why does the OpenSSL test fail with "bc: stack empty"?
472
473On some DG/ux versions, bc seems to have a too small stack for calculations
474that the OpenSSL bntest throws at it. This gets triggered when you run the
475test suite (using "make test"). The message returned is "bc: stack empty".
476
477The best way to deal with this is to find another implementation of bc
478and compile/install it. GNU bc (see http://www.gnu.org/software/software.html
479for download instructions) can be safely used, for example.
480
481
482* Why does the OpenSSL compilation fail on Alpha Tru64 Unix?
483
484On some Alpha installations running Tru64 Unix and Compaq C, the compilation
485of crypto/sha/sha_dgst.c fails with the message 'Fatal: Insufficient virtual
486memory to continue compilation.' As far as the tests have shown, this may be
487a compiler bug. What happens is that it eats up a lot of resident memory
488to build something, probably a table. The problem is clearly in the
489optimization code, because if one eliminates optimization completely (-O0),
490the compilation goes through (and the compiler consumes about 2MB of resident
491memory instead of 240MB or whatever one's limit is currently).
492
493There are three options to solve this problem:
494
4951. set your current data segment size soft limit higher. Experience shows
496that about 241000 kbytes seems to be enough on an AlphaServer DS10. You do
497this with the command 'ulimit -Sd nnnnnn', where 'nnnnnn' is the number of
498kbytes to set the limit to.
499
5002. If you have a hard limit that is lower than what you need and you can't
501get it changed, you can compile all of OpenSSL with -O0 as optimization
502level. This is however not a very nice thing to do for those who expect to
503get the best result from OpenSSL. A bit more complicated solution is the
504following:
505
506----- snip:start -----
507 make DIRS=crypto SDIRS=sha "`grep '^CFLAG=' Makefile.ssl | \
508 sed -e 's/ -O[0-9] / -O0 /'`"
509 rm `ls crypto/*.o crypto/sha/*.o | grep -v 'sha_dgst\.o'`
510 make
511----- snip:end -----
512
513This will only compile sha_dgst.c with -O0, the rest with the optimization
514level chosen by the configuration process. When the above is done, do the
515test and installation and you're set.
516
5173. Reconfigure the toolkit with no-sha0 option to leave out SHA0. It
518should not be used and is not used in SSL/TLS nor any other recognized
519protocol in either case.
520
521
522* Why does the OpenSSL compilation fail with "ar: command not found"?
523
524Getting this message is quite usual on Solaris 2, because Sun has hidden
525away 'ar' and other development commands in directories that aren't in
526$PATH by default. One of those directories is '/usr/ccs/bin'. The
527quickest way to fix this is to do the following (it assumes you use sh
528or any sh-compatible shell):
529
530----- snip:start -----
531 PATH=${PATH}:/usr/ccs/bin; export PATH
532----- snip:end -----
533
534and then redo the compilation. What you should really do is make sure
535'/usr/ccs/bin' is permanently in your $PATH, for example through your
536'.profile' (again, assuming you use a sh-compatible shell).
537
538
539* Why does the OpenSSL compilation fail on Win32 with VC++?
540
541Sometimes, you may get reports from VC++ command line (cl) that it
542can't find standard include files like stdio.h and other weirdnesses.
543One possible cause is that the environment isn't correctly set up.
544To solve that problem for VC++ versions up to 6, one should run
545VCVARS32.BAT which is found in the 'bin' subdirectory of the VC++
546installation directory (somewhere under 'Program Files'). For VC++
547version 7 (and up?), which is also called VS.NET, the file is called
548VSVARS32.BAT instead.
549This needs to be done prior to running NMAKE, and the changes are only
550valid for the current DOS session.
551
552
553* What is special about OpenSSL on Redhat?
554
555Red Hat Linux (release 7.0 and later) include a preinstalled limited
556version of OpenSSL. For patent reasons, support for IDEA, RC5 and MDC2
557is disabled in this version. The same may apply to other Linux distributions.
558Users may therefore wish to install more or all of the features left out.
559
560To do this you MUST ensure that you do not overwrite the openssl that is in
561/usr/bin on your Red Hat machine. Several packages depend on this file,
562including sendmail and ssh. /usr/local/bin is a good alternative choice. The
563libraries that come with Red Hat 7.0 onwards have different names and so are
564not affected. (eg For Red Hat 7.2 they are /lib/libssl.so.0.9.6b and
565/lib/libcrypto.so.0.9.6b with symlinks /lib/libssl.so.2 and
566/lib/libcrypto.so.2 respectively).
567
568Please note that we have been advised by Red Hat attempting to recompile the
569openssl rpm with all the cryptography enabled will not work. All other
570packages depend on the original Red Hat supplied openssl package. It is also
571worth noting that due to the way Red Hat supplies its packages, updates to
572openssl on each distribution never change the package version, only the
573build number. For example, on Red Hat 7.1, the latest openssl package has
574version number 0.9.6 and build number 9 even though it contains all the
575relevant updates in packages up to and including 0.9.6b.
576
577A possible way around this is to persuade Red Hat to produce a non-US
578version of Red Hat Linux.
579
580FYI: Patent numbers and expiry dates of US patents:
581MDC-2: 4,908,861 13/03/2007
582IDEA: 5,214,703 25/05/2010
583RC5: 5,724,428 03/03/2015
584
585
586* Why does the OpenSSL compilation fail on MacOS X?
587
588If the failure happens when trying to build the "openssl" binary, with
589a large number of undefined symbols, it's very probable that you have
590OpenSSL 0.9.6b delivered with the operating system (you can find out by
591running '/usr/bin/openssl version') and that you were trying to build
592OpenSSL 0.9.7 or newer. The problem is that the loader ('ld') in
593MacOS X has a misfeature that's quite difficult to go around.
594Look in the file PROBLEMS for a more detailed explanation and for possible
595solutions.
596
597
598* Why does the OpenSSL test suite fail on MacOS X?
599
600If the failure happens when running 'make test' and the RC4 test fails,
601it's very probable that you have OpenSSL 0.9.6b delivered with the
602operating system (you can find out by running '/usr/bin/openssl version')
603and that you were trying to build OpenSSL 0.9.6d. The problem is that
604the loader ('ld') in MacOS X has a misfeature that's quite difficult to
605go around and has linked the programs "openssl" and the test programs
606with /usr/lib/libcrypto.dylib and /usr/lib/libssl.dylib instead of the
607libraries you just built.
608Look in the file PROBLEMS for a more detailed explanation and for possible
609solutions.
610
611* Why does the OpenSSL test suite fail in BN_sqr test [on a 64-bit platform]?
612
613Failure in BN_sqr test is most likely caused by a failure to configure the
614toolkit for current platform or lack of support for the platform in question.
615Run './config -t' and './apps/openssl version -p'. Do these platform
616identifiers match? If they don't, then you most likely failed to run
617./config and you're hereby advised to do so before filing a bug report.
618If ./config itself fails to run, then it's most likely problem with your
619local environment and you should turn to your system administrator (or
620similar). If identifiers match (and/or no alternative identifier is
621suggested by ./config script), then the platform is unsupported. There might
622or might not be a workaround. Most notably on SPARC64 platforms with GNU
623C compiler you should be able to produce a working build by running
624'./config -m32'. I understand that -m32 might not be what you want/need,
625but the build should be operational. For further details turn to
626<openssl-dev@openssl.org>.
627
628* Why does OpenBSD-i386 build fail on des-586.s with "Unimplemented segment type"?
629
630As of 0.9.7 assembler routines were overhauled for position independence
631of the machine code, which is essential for shared library support. For
632some reason OpenBSD is equipped with an out-of-date GNU assembler which
633finds the new code offensive. To work around the problem, configure with
634no-asm (and sacrifice a great deal of performance) or patch your assembler
635according to <URL: http://www.openssl.org/~appro/gas-1.92.3.OpenBSD.patch>.
636For your convenience a pre-compiled replacement binary is provided at
637<URL: http://www.openssl.org/~appro/gas-1.92.3.static.aout.bin>.
638Reportedly elder *BSD a.out platforms also suffer from this problem and
639remedy should be same. Provided binary is statically linked and should be
640working across wider range of *BSD branches, not just OpenBSD.
641
642* Why does the OpenSSL test suite fail in sha512t on x86 CPU?
643
644If the test program in question fails withs SIGILL, Illegal Instruction
645exception, then you more than likely to run SSE2-capable CPU, such as
646Intel P4, under control of kernel which does not support SSE2
647instruction extentions. See accompanying INSTALL file and
648OPENSSL_ia32cap(3) documentation page for further information.
649
650* Why does compiler fail to compile sha512.c?
651
652OpenSSL SHA-512 implementation depends on compiler support for 64-bit
653integer type. Few elder compilers [ULTRIX cc, SCO compiler to mention a
654couple] lack support for this and therefore are incapable of compiling
655the module in question. The recommendation is to disable SHA-512 by
656adding no-sha512 to ./config [or ./Configure] command line. Another
657possible alternative might be to switch to GCC.
658
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659* Test suite still fails, what to do?
660
661Another common reason for failure to complete some particular test is
662simply bad code generated by a buggy component in toolchain or deficiency
663in run-time environment. There are few cases documented in PROBLEMS file,
664consult it for possible workaround before you beat the drum. Even if you
665don't find solution or even mention there, do reserve for possibility of
666a compiler bug. Compiler bugs might appear in rather bizarre ways, they
667never make sense, and tend to emerge when you least expect them. In order
668to identify one, drop optimization level, e.g. by editing CFLAG line in
669top-level Makefile, recompile and re-run the test.
670
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671[PROG] ========================================================================
672
673* Is OpenSSL thread-safe?
674
675Yes (with limitations: an SSL connection may not concurrently be used
676by multiple threads). On Windows and many Unix systems, OpenSSL
677automatically uses the multi-threaded versions of the standard
678libraries. If your platform is not one of these, consult the INSTALL
679file.
680
681Multi-threaded applications must provide two callback functions to
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682OpenSSL by calling CRYPTO_set_locking_callback() and
683CRYPTO_set_id_callback(). This is described in the threads(3)
684manpage.
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685
686* I've compiled a program under Windows and it crashes: why?
687
688This is usually because you've missed the comment in INSTALL.W32.
689Your application must link against the same version of the Win32
690C-Runtime against which your openssl libraries were linked. The
691default version for OpenSSL is /MD - "Multithreaded DLL".
692
693If you are using Microsoft Visual C++'s IDE (Visual Studio), in
694many cases, your new project most likely defaulted to "Debug
695Singlethreaded" - /ML. This is NOT interchangeable with /MD and your
696program will crash, typically on the first BIO related read or write
697operation.
698
699For each of the six possible link stage configurations within Win32,
700your application must link against the same by which OpenSSL was
701built. If you are using MS Visual C++ (Studio) this can be changed
702by:
703
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704 1. Select Settings... from the Project Menu.
705 2. Select the C/C++ Tab.
706 3. Select "Code Generation from the "Category" drop down list box
707 4. Select the Appropriate library (see table below) from the "Use
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708 run-time library" drop down list box. Perform this step for both
709 your debug and release versions of your application (look at the
710 top left of the settings panel to change between the two)
711
712 Single Threaded /ML - MS VC++ often defaults to
713 this for the release
714 version of a new project.
715 Debug Single Threaded /MLd - MS VC++ often defaults to
716 this for the debug version
717 of a new project.
718 Multithreaded /MT
719 Debug Multithreaded /MTd
720 Multithreaded DLL /MD - OpenSSL defaults to this.
721 Debug Multithreaded DLL /MDd
722
723Note that debug and release libraries are NOT interchangeable. If you
724built OpenSSL with /MD your application must use /MD and cannot use /MDd.
725
726As per 0.9.8 the above limitation is eliminated for .DLLs. OpenSSL
74093195 727.DLLs compiled with some specific run-time option [we insist on the
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728default /MD] can be deployed with application compiled with different
729option or even different compiler. But there is a catch! Instead of
730re-compiling OpenSSL toolkit, as you would have to with prior versions,
731you have to compile small C snippet with compiler and/or options of
732your choice. The snippet gets installed as
733<install-root>/include/openssl/applink.c and should be either added to
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734your application project or simply #include-d in one [and only one]
735of your application source files. Failure to link this shim module
736into your application manifests itself as fatal "no OPENSSL_Applink"
737run-time error. An explicit reminder is due that in this situation
738[mixing compiler options] it is as important to add CRYPTO_malloc_init
739prior first call to OpenSSL.
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740
741* How do I read or write a DER encoded buffer using the ASN1 functions?
742
743You have two options. You can either use a memory BIO in conjunction
744with the i2d_*_bio() or d2i_*_bio() functions or you can use the
745i2d_*(), d2i_*() functions directly. Since these are often the
746cause of grief here are some code fragments using PKCS7 as an example:
747
748 unsigned char *buf, *p;
749 int len;
750
751 len = i2d_PKCS7(p7, NULL);
752 buf = OPENSSL_malloc(len); /* or Malloc, error checking omitted */
753 p = buf;
754 i2d_PKCS7(p7, &p);
755
756At this point buf contains the len bytes of the DER encoding of
757p7.
758
759The opposite assumes we already have len bytes in buf:
760
761 unsigned char *p;
762 p = buf;
763 p7 = d2i_PKCS7(NULL, &p, len);
764
765At this point p7 contains a valid PKCS7 structure of NULL if an error
766occurred. If an error occurred ERR_print_errors(bio) should give more
767information.
768
769The reason for the temporary variable 'p' is that the ASN1 functions
770increment the passed pointer so it is ready to read or write the next
771structure. This is often a cause of problems: without the temporary
772variable the buffer pointer is changed to point just after the data
773that has been read or written. This may well be uninitialized data
774and attempts to free the buffer will have unpredictable results
775because it no longer points to the same address.
776
777
778* OpenSSL uses DER but I need BER format: does OpenSSL support BER?
779
780The short answer is yes, because DER is a special case of BER and OpenSSL
781ASN1 decoders can process BER.
782
783The longer answer is that ASN1 structures can be encoded in a number of
784different ways. One set of ways is the Basic Encoding Rules (BER) with various
785permissible encodings. A restriction of BER is the Distinguished Encoding
786Rules (DER): these uniquely specify how a given structure is encoded.
787
788Therefore, because DER is a special case of BER, DER is an acceptable encoding
789for BER.
790
791
792* I've tried using <M_some_evil_pkcs12_macro> and I get errors why?
793
794This usually happens when you try compiling something using the PKCS#12
795macros with a C++ compiler. There is hardly ever any need to use the
796PKCS#12 macros in a program, it is much easier to parse and create
797PKCS#12 files using the PKCS12_parse() and PKCS12_create() functions
798documented in doc/openssl.txt and with examples in demos/pkcs12. The
799'pkcs12' application has to use the macros because it prints out
800debugging information.
801
802
803* I've called <some function> and it fails, why?
804
805Before submitting a report or asking in one of the mailing lists, you
806should try to determine the cause. In particular, you should call
807ERR_print_errors() or ERR_print_errors_fp() after the failed call
808and see if the message helps. Note that the problem may occur earlier
809than you think -- you should check for errors after every call where
810it is possible, otherwise the actual problem may be hidden because
811some OpenSSL functions clear the error state.
812
813
814* I just get a load of numbers for the error output, what do they mean?
815
816The actual format is described in the ERR_print_errors() manual page.
817You should call the function ERR_load_crypto_strings() before hand and
818the message will be output in text form. If you can't do this (for example
819it is a pre-compiled binary) you can use the errstr utility on the error
820code itself (the hex digits after the second colon).
821
822
823* Why do I get errors about unknown algorithms?
824
825This can happen under several circumstances such as reading in an
826encrypted private key or attempting to decrypt a PKCS#12 file. The cause
827is forgetting to load OpenSSL's table of algorithms with
828OpenSSL_add_all_algorithms(). See the manual page for more information.
829
830
831* Why can't the OpenSSH configure script detect OpenSSL?
832
833Several reasons for problems with the automatic detection exist.
834OpenSSH requires at least version 0.9.5a of the OpenSSL libraries.
835Sometimes the distribution has installed an older version in the system
836locations that is detected instead of a new one installed. The OpenSSL
837library might have been compiled for another CPU or another mode (32/64 bits).
838Permissions might be wrong.
839
840The general answer is to check the config.log file generated when running
841the OpenSSH configure script. It should contain the detailed information
842on why the OpenSSL library was not detected or considered incompatible.
843
844
845* Can I use OpenSSL's SSL library with non-blocking I/O?
846
847Yes; make sure to read the SSL_get_error(3) manual page!
848
849A pitfall to avoid: Don't assume that SSL_read() will just read from
850the underlying transport or that SSL_write() will just write to it --
851it is also possible that SSL_write() cannot do any useful work until
852there is data to read, or that SSL_read() cannot do anything until it
853is possible to send data. One reason for this is that the peer may
854request a new TLS/SSL handshake at any time during the protocol,
855requiring a bi-directional message exchange; both SSL_read() and
856SSL_write() will try to continue any pending handshake.
857
858
859* Why doesn't my server application receive a client certificate?
860
861Due to the TLS protocol definition, a client will only send a certificate,
862if explicitly asked by the server. Use the SSL_VERIFY_PEER flag of the
863SSL_CTX_set_verify() function to enable the use of client certificates.
864
865
866* Why does compilation fail due to an undefined symbol NID_uniqueIdentifier?
867
868For OpenSSL 0.9.7 the OID table was extended and corrected. In earlier
869versions, uniqueIdentifier was incorrectly used for X.509 certificates.
870The correct name according to RFC2256 (LDAP) is x500UniqueIdentifier.
871Change your code to use the new name when compiling against OpenSSL 0.9.7.
872
873
874* I think I've detected a memory leak, is this a bug?
875
876In most cases the cause of an apparent memory leak is an OpenSSL internal table
877that is allocated when an application starts up. Since such tables do not grow
878in size over time they are harmless.
879
880These internal tables can be freed up when an application closes using various
881functions. Currently these include following:
882
883Thread-local cleanup functions:
884
885 ERR_remove_state()
886
887Application-global cleanup functions that are aware of usage (and therefore
888thread-safe):
889
890 ENGINE_cleanup() and CONF_modules_unload()
891
892"Brutal" (thread-unsafe) Application-global cleanup functions:
893
894 ERR_free_strings(), EVP_cleanup() and CRYPTO_cleanup_all_ex_data().
895
896
897===============================================================================
898