Add files to OpenSSL that will generate optimized asm code.
[dragonfly.git] / crypto / openssl / 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?
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* Where are the declarations and implementations of d2i_X509() etc?
74
75===============================================================================
76
77[MISC] ========================================================================
78
79* Which is the current version of OpenSSL?
80
81The current version is available from <URL: http://www.openssl.org>.
82OpenSSL 1.0.0b was released on Nov 16th, 2010.
83
84In addition to the current stable release, you can also access daily
85snapshots of the OpenSSL development version at <URL:
86ftp://ftp.openssl.org/snapshot/>, or get it by anonymous CVS access.
87
88
89* Where is the documentation?
90
91OpenSSL is a library that provides cryptographic functionality to
92applications such as secure web servers. Be sure to read the
93documentation of the application you want to use. The INSTALL file
94explains how to install this library.
95
96OpenSSL includes a command line utility that can be used to perform a
97variety of cryptographic functions. It is described in the openssl(1)
98manpage. Documentation for developers is currently being written. Many
99manual pages are available; overviews over libcrypto and
100libssl are given in the crypto(3) and ssl(3) manpages.
101
102The OpenSSL manpages are installed in /usr/local/ssl/man/ (or a
103different directory if you specified one as described in INSTALL).
104In addition, you can read the most current versions at
105<URL: http://www.openssl.org/docs/>. Note that the online documents refer
106to the very latest development versions of OpenSSL and may include features
107not present in released versions. If in doubt refer to the documentation
108that came with the version of OpenSSL you are using.
109
110For information on parts of libcrypto that are not yet documented, you
111might want to read Ariel Glenn's documentation on SSLeay 0.9, OpenSSL's
112predecessor, at <URL: http://www.columbia.edu/~ariel/ssleay/>. Much
113of this still applies to OpenSSL.
114
115There is some documentation about certificate extensions and PKCS#12
116in doc/openssl.txt
117
118The original SSLeay documentation is included in OpenSSL as
119doc/ssleay.txt. It may be useful when none of the other resources
120help, but please note that it reflects the obsolete version SSLeay
1210.6.6.
122
123
124* How can I contact the OpenSSL developers?
125
126The README file describes how to submit bug reports and patches to
127OpenSSL. Information on the OpenSSL mailing lists is available from
128<URL: http://www.openssl.org>.
129
130
131* Where can I get a compiled version of OpenSSL?
132
133You can finder pointers to binary distributions in
134http://www.openssl.org/related/binaries.html .
135
136Some applications that use OpenSSL are distributed in binary form.
137When using such an application, you don't need to install OpenSSL
138yourself; the application will include the required parts (e.g. DLLs).
139
140If you want to build OpenSSL on a Windows system and you don't have
141a C compiler, read the "Mingw32" section of INSTALL.W32 for information
142on how to obtain and install the free GNU C compiler.
143
144A number of Linux and *BSD distributions include OpenSSL.
145
146
147* Why aren't tools like 'autoconf' and 'libtool' used?
148
149autoconf will probably be used in future OpenSSL versions. If it was
150less Unix-centric, it might have been used much earlier.
151
152* What is an 'engine' version?
153
154With version 0.9.6 OpenSSL was extended to interface to external crypto
155hardware. This was realized in a special release '0.9.6-engine'. With
156version 0.9.7 the changes were merged into the main development line,
157so that the special release is no longer necessary.
158
159* How do I check the authenticity of the OpenSSL distribution?
160
161We provide MD5 digests and ASC signatures of each tarball.
162Use MD5 to check that a tarball from a mirror site is identical:
163
164 md5sum TARBALL | awk '{print $1;}' | cmp - TARBALL.md5
165
166You can check authenticity using pgp or gpg. You need the OpenSSL team
167member public key used to sign it (download it from a key server, see a
168list of keys at <URL: http://www.openssl.org/about/>). Then
169just do:
170
171 pgp TARBALL.asc
172
173[LEGAL] =======================================================================
174
175* Do I need patent licenses to use OpenSSL?
176
177The patents section of the README file lists patents that may apply to
178you if you want to use OpenSSL. For information on intellectual
179property rights, please consult a lawyer. The OpenSSL team does not
180offer legal advice.
181
182You can configure OpenSSL so as not to use IDEA, MDC2 and RC5 by using
183 ./config no-idea no-mdc2 no-rc5
184
185
186* Can I use OpenSSL with GPL software?
187
188On many systems including the major Linux and BSD distributions, yes (the
189GPL does not place restrictions on using libraries that are part of the
190normal operating system distribution).
191
192On other systems, the situation is less clear. Some GPL software copyright
193holders claim that you infringe on their rights if you use OpenSSL with
194their software on operating systems that don't normally include OpenSSL.
195
196If you develop open source software that uses OpenSSL, you may find it
197useful to choose an other license than the GPL, or state explicitly that
198"This program is released under the GPL with the additional exemption that
199compiling, linking, and/or using OpenSSL is allowed." If you are using
200GPL software developed by others, you may want to ask the copyright holder
201for permission to use their software with OpenSSL.
202
203
204[USER] ========================================================================
205
206* Why do I get a "PRNG not seeded" error message?
207
208Cryptographic software needs a source of unpredictable data to work
209correctly. Many open source operating systems provide a "randomness
210device" (/dev/urandom or /dev/random) that serves this purpose.
211All OpenSSL versions try to use /dev/urandom by default; starting with
212version 0.9.7, OpenSSL also tries /dev/random if /dev/urandom is not
213available.
214
215On other systems, applications have to call the RAND_add() or
216RAND_seed() function with appropriate data before generating keys or
217performing public key encryption. (These functions initialize the
218pseudo-random number generator, PRNG.) Some broken applications do
219not do this. As of version 0.9.5, the OpenSSL functions that need
220randomness report an error if the random number generator has not been
221seeded with at least 128 bits of randomness. If this error occurs and
222is not discussed in the documentation of the application you are
223using, please contact the author of that application; it is likely
224that it never worked correctly. OpenSSL 0.9.5 and later make the
225error visible by refusing to perform potentially insecure encryption.
226
227If you are using Solaris 8, you can add /dev/urandom and /dev/random
228devices by installing patch 112438 (Sparc) or 112439 (x86), which are
229available via the Patchfinder at <URL: http://sunsolve.sun.com>
230(Solaris 9 includes these devices by default). For /dev/random support
231for earlier Solaris versions, see Sun's statement at
232<URL: http://sunsolve.sun.com/pub-cgi/retrieve.pl?doc=fsrdb/27606&zone_32=SUNWski>
233(the SUNWski package is available in patch 105710).
234
235On systems without /dev/urandom and /dev/random, it is a good idea to
236use the Entropy Gathering Demon (EGD); see the RAND_egd() manpage for
237details. Starting with version 0.9.7, OpenSSL will automatically look
238for an EGD socket at /var/run/egd-pool, /dev/egd-pool, /etc/egd-pool and
239/etc/entropy.
240
241Most components of the openssl command line utility automatically try
242to seed the random number generator from a file. The name of the
243default seeding file is determined as follows: If environment variable
244RANDFILE is set, then it names the seeding file. Otherwise if
245environment variable HOME is set, then the seeding file is $HOME/.rnd.
246If neither RANDFILE nor HOME is set, versions up to OpenSSL 0.9.6 will
247use file .rnd in the current directory while OpenSSL 0.9.6a uses no
248default seeding file at all. OpenSSL 0.9.6b and later will behave
249similarly to 0.9.6a, but will use a default of "C:\" for HOME on
250Windows systems if the environment variable has not been set.
251
252If the default seeding file does not exist or is too short, the "PRNG
253not seeded" error message may occur.
254
255The openssl command line utility will write back a new state to the
256default seeding file (and create this file if necessary) unless
257there was no sufficient seeding.
258
259Pointing $RANDFILE to an Entropy Gathering Daemon socket does not work.
260Use the "-rand" option of the OpenSSL command line tools instead.
261The $RANDFILE environment variable and $HOME/.rnd are only used by the
262OpenSSL command line tools. Applications using the OpenSSL library
263provide their own configuration options to specify the entropy source,
264please check out the documentation coming the with application.
265
266
267* Why do I get an "unable to write 'random state'" error message?
268
269
270Sometimes the openssl command line utility does not abort with
271a "PRNG not seeded" error message, but complains that it is
272"unable to write 'random state'". This message refers to the
273default seeding file (see previous answer). A possible reason
274is that no default filename is known because neither RANDFILE
275nor HOME is set. (Versions up to 0.9.6 used file ".rnd" in the
276current directory in this case, but this has changed with 0.9.6a.)
277
278
279* How do I create certificates or certificate requests?
280
281Check out the CA.pl(1) manual page. This provides a simple wrapper round
282the 'req', 'verify', 'ca' and 'pkcs12' utilities. For finer control check
283out the manual pages for the individual utilities and the certificate
284extensions documentation (currently in doc/openssl.txt).
285
286
287* Why can't I create certificate requests?
288
289You typically get the error:
290
291 unable to find 'distinguished_name' in config
292 problems making Certificate Request
293
294This is because it can't find the configuration file. Check out the
295DIAGNOSTICS section of req(1) for more information.
296
297
298* Why does <SSL program> fail with a certificate verify error?
299
300This problem is usually indicated by log messages saying something like
301"unable to get local issuer certificate" or "self signed certificate".
302When a certificate is verified its root CA must be "trusted" by OpenSSL
303this typically means that the CA certificate must be placed in a directory
304or file and the relevant program configured to read it. The OpenSSL program
305'verify' behaves in a similar way and issues similar error messages: check
306the verify(1) program manual page for more information.
307
308
309* Why can I only use weak ciphers when I connect to a server using OpenSSL?
310
311This is almost certainly because you are using an old "export grade" browser
312which only supports weak encryption. Upgrade your browser to support 128 bit
313ciphers.
314
315
316* How can I create DSA certificates?
317
318Check the CA.pl(1) manual page for a DSA certificate example.
319
320
321* Why can't I make an SSL connection to a server using a DSA certificate?
322
323Typically you'll see a message saying there are no shared ciphers when
324the same setup works fine with an RSA certificate. There are two possible
325causes. The client may not support connections to DSA servers most web
326browsers (including Netscape and MSIE) only support connections to servers
327supporting RSA cipher suites. The other cause is that a set of DH parameters
328has not been supplied to the server. DH parameters can be created with the
329dhparam(1) command and loaded using the SSL_CTX_set_tmp_dh() for example:
330check the source to s_server in apps/s_server.c for an example.
331
332
333* How can I remove the passphrase on a private key?
334
335Firstly you should be really *really* sure you want to do this. Leaving
336a private key unencrypted is a major security risk. If you decide that
337you do have to do this check the EXAMPLES sections of the rsa(1) and
338dsa(1) manual pages.
339
340
341* Why can't I use OpenSSL certificates with SSL client authentication?
342
343What will typically happen is that when a server requests authentication
344it will either not include your certificate or tell you that you have
345no client certificates (Netscape) or present you with an empty list box
346(MSIE). The reason for this is that when a server requests a client
347certificate it includes a list of CAs names which it will accept. Browsers
348will only let you select certificates from the list on the grounds that
349there is little point presenting a certificate which the server will
350reject.
351
352The solution is to add the relevant CA certificate to your servers "trusted
353CA list". How you do this depends on the server software in uses. You can
354print out the servers list of acceptable CAs using the OpenSSL s_client tool:
355
356openssl s_client -connect www.some.host:443 -prexit
357
358If your server only requests certificates on certain URLs then you may need
359to manually issue an HTTP GET command to get the list when s_client connects:
360
361GET /some/page/needing/a/certificate.html
362
363If your CA does not appear in the list then this confirms the problem.
364
365
366* Why does my browser give a warning about a mismatched hostname?
367
368Browsers expect the server's hostname to match the value in the commonName
369(CN) field of the certificate. If it does not then you get a warning.
370
371
372* How do I install a CA certificate into a browser?
373
374The usual way is to send the DER encoded certificate to the browser as
375MIME type application/x-x509-ca-cert, for example by clicking on an appropriate
376link. On MSIE certain extensions such as .der or .cacert may also work, or you
377can import the certificate using the certificate import wizard.
378
379You can convert a certificate to DER form using the command:
380
381openssl x509 -in ca.pem -outform DER -out ca.der
382
383Occasionally someone suggests using a command such as:
384
385openssl pkcs12 -export -out cacert.p12 -in cacert.pem -inkey cakey.pem
386
387DO NOT DO THIS! This command will give away your CAs private key and
388reduces its security to zero: allowing anyone to forge certificates in
389whatever name they choose.
390
391* Why is OpenSSL x509 DN output not conformant to RFC2253?
392
393The ways to print out the oneline format of the DN (Distinguished Name) have
394been extended in version 0.9.7 of OpenSSL. Using the new X509_NAME_print_ex()
395interface, the "-nameopt" option could be introduded. See the manual
396page of the "openssl x509" commandline tool for details. The old behaviour
397has however been left as default for the sake of compatibility.
398
399* What is a "128 bit certificate"? Can I create one with OpenSSL?
400
401The term "128 bit certificate" is a highly misleading marketing term. It does
402*not* refer to the size of the public key in the certificate! A certificate
403containing a 128 bit RSA key would have negligible security.
404
405There were various other names such as "magic certificates", "SGC
406certificates", "step up certificates" etc.
407
408You can't generally create such a certificate using OpenSSL but there is no
409need to any more. Nowadays web browsers using unrestricted strong encryption
410are generally available.
411
412When there were tight restrictions on the export of strong encryption
413software from the US only weak encryption algorithms could be freely exported
414(initially 40 bit and then 56 bit). It was widely recognised that this was
415inadequate. A relaxation of the rules allowed the use of strong encryption but
416only to an authorised server.
417
418Two slighly different techniques were developed to support this, one used by
419Netscape was called "step up", the other used by MSIE was called "Server Gated
420Cryptography" (SGC). When a browser initially connected to a server it would
421check to see if the certificate contained certain extensions and was issued by
422an authorised authority. If these test succeeded it would reconnect using
423strong encryption.
424
425Only certain (initially one) certificate authorities could issue the
426certificates and they generally cost more than ordinary certificates.
427
428Although OpenSSL can create certificates containing the appropriate extensions
429the certificate would not come from a permitted authority and so would not
430be recognized.
431
432The export laws were later changed to allow almost unrestricted use of strong
433encryption so these certificates are now obsolete.
434
435
436* Why does OpenSSL set the authority key identifier (AKID) extension incorrectly?
437
438It doesn't: this extension is often the cause of confusion.
439
440Consider a certificate chain A->B->C so that A signs B and B signs C. Suppose
441certificate C contains AKID.
442
443The purpose of this extension is to identify the authority certificate B. This
444can be done either by including the subject key identifier of B or its issuer
445name and serial number.
446
447In this latter case because it is identifying certifcate B it must contain the
448issuer name and serial number of B.
449
450It is often wrongly assumed that it should contain the subject name of B. If it
451did this would be redundant information because it would duplicate the issuer
452name of C.
453
454
455* How can I set up a bundle of commercial root CA certificates?
456
457The OpenSSL software is shipped without any root CA certificate as the
458OpenSSL project does not have any policy on including or excluding
459any specific CA and does not intend to set up such a policy. Deciding
460about which CAs to support is up to application developers or
461administrators.
462
463Other projects do have other policies so you can for example extract the CA
464bundle used by Mozilla and/or modssl as described in this article:
465
466 http://www.mail-archive.com/modssl-users@modssl.org/msg16980.html
467
468
469[BUILD] =======================================================================
470
471* Why does the linker complain about undefined symbols?
472
473Maybe the compilation was interrupted, and make doesn't notice that
474something is missing. Run "make clean; make".
475
476If you used ./Configure instead of ./config, make sure that you
477selected the right target. File formats may differ slightly between
478OS versions (for example sparcv8/sparcv9, or a.out/elf).
479
480In case you get errors about the following symbols, use the config
481option "no-asm", as described in INSTALL:
482
483 BF_cbc_encrypt, BF_decrypt, BF_encrypt, CAST_cbc_encrypt,
484 CAST_decrypt, CAST_encrypt, RC4, RC5_32_cbc_encrypt, RC5_32_decrypt,
485 RC5_32_encrypt, bn_add_words, bn_div_words, bn_mul_add_words,
486 bn_mul_comba4, bn_mul_comba8, bn_mul_words, bn_sqr_comba4,
487 bn_sqr_comba8, bn_sqr_words, bn_sub_words, des_decrypt3,
488 des_ede3_cbc_encrypt, des_encrypt, des_encrypt2, des_encrypt3,
489 des_ncbc_encrypt, md5_block_asm_host_order, sha1_block_asm_data_order
490
491If none of these helps, you may want to try using the current snapshot.
492If the problem persists, please submit a bug report.
493
494
495* Why does the OpenSSL test fail with "bc: command not found"?
496
497You didn't install "bc", the Unix calculator. If you want to run the
498tests, get GNU bc from ftp://ftp.gnu.org or from your OS distributor.
499
500
501* Why does the OpenSSL test fail with "bc: 1 no implemented"?
502
503On some SCO installations or versions, bc has a bug that gets triggered
504when you run the test suite (using "make test"). The message returned is
505"bc: 1 not implemented".
506
507The best way to deal with this is to find another implementation of bc
508and compile/install it. GNU bc (see http://www.gnu.org/software/software.html
509for download instructions) can be safely used, for example.
510
511
512* Why does the OpenSSL test fail with "bc: stack empty"?
513
514On some DG/ux versions, bc seems to have a too small stack for calculations
515that the OpenSSL bntest throws at it. This gets triggered when you run the
516test suite (using "make test"). The message returned is "bc: stack empty".
517
518The best way to deal with this is to find another implementation of bc
519and compile/install it. GNU bc (see http://www.gnu.org/software/software.html
520for download instructions) can be safely used, for example.
521
522
523* Why does the OpenSSL compilation fail on Alpha Tru64 Unix?
524
525On some Alpha installations running Tru64 Unix and Compaq C, the compilation
526of crypto/sha/sha_dgst.c fails with the message 'Fatal: Insufficient virtual
527memory to continue compilation.' As far as the tests have shown, this may be
528a compiler bug. What happens is that it eats up a lot of resident memory
529to build something, probably a table. The problem is clearly in the
530optimization code, because if one eliminates optimization completely (-O0),
531the compilation goes through (and the compiler consumes about 2MB of resident
532memory instead of 240MB or whatever one's limit is currently).
533
534There are three options to solve this problem:
535
5361. set your current data segment size soft limit higher. Experience shows
537that about 241000 kbytes seems to be enough on an AlphaServer DS10. You do
538this with the command 'ulimit -Sd nnnnnn', where 'nnnnnn' is the number of
539kbytes to set the limit to.
540
5412. If you have a hard limit that is lower than what you need and you can't
542get it changed, you can compile all of OpenSSL with -O0 as optimization
543level. This is however not a very nice thing to do for those who expect to
544get the best result from OpenSSL. A bit more complicated solution is the
545following:
546
547----- snip:start -----
548 make DIRS=crypto SDIRS=sha "`grep '^CFLAG=' Makefile.ssl | \
549 sed -e 's/ -O[0-9] / -O0 /'`"
550 rm `ls crypto/*.o crypto/sha/*.o | grep -v 'sha_dgst\.o'`
551 make
552----- snip:end -----
553
554This will only compile sha_dgst.c with -O0, the rest with the optimization
555level chosen by the configuration process. When the above is done, do the
556test and installation and you're set.
557
5583. Reconfigure the toolkit with no-sha0 option to leave out SHA0. It
559should not be used and is not used in SSL/TLS nor any other recognized
560protocol in either case.
561
562
563* Why does the OpenSSL compilation fail with "ar: command not found"?
564
565Getting this message is quite usual on Solaris 2, because Sun has hidden
566away 'ar' and other development commands in directories that aren't in
567$PATH by default. One of those directories is '/usr/ccs/bin'. The
568quickest way to fix this is to do the following (it assumes you use sh
569or any sh-compatible shell):
570
571----- snip:start -----
572 PATH=${PATH}:/usr/ccs/bin; export PATH
573----- snip:end -----
574
575and then redo the compilation. What you should really do is make sure
576'/usr/ccs/bin' is permanently in your $PATH, for example through your
577'.profile' (again, assuming you use a sh-compatible shell).
578
579
580* Why does the OpenSSL compilation fail on Win32 with VC++?
581
582Sometimes, you may get reports from VC++ command line (cl) that it
583can't find standard include files like stdio.h and other weirdnesses.
584One possible cause is that the environment isn't correctly set up.
585To solve that problem for VC++ versions up to 6, one should run
586VCVARS32.BAT which is found in the 'bin' subdirectory of the VC++
587installation directory (somewhere under 'Program Files'). For VC++
588version 7 (and up?), which is also called VS.NET, the file is called
589VSVARS32.BAT instead.
590This needs to be done prior to running NMAKE, and the changes are only
591valid for the current DOS session.
592
593
594* What is special about OpenSSL on Redhat?
595
596Red Hat Linux (release 7.0 and later) include a preinstalled limited
597version of OpenSSL. For patent reasons, support for IDEA, RC5 and MDC2
598is disabled in this version. The same may apply to other Linux distributions.
599Users may therefore wish to install more or all of the features left out.
600
601To do this you MUST ensure that you do not overwrite the openssl that is in
602/usr/bin on your Red Hat machine. Several packages depend on this file,
603including sendmail and ssh. /usr/local/bin is a good alternative choice. The
604libraries that come with Red Hat 7.0 onwards have different names and so are
605not affected. (eg For Red Hat 7.2 they are /lib/libssl.so.0.9.6b and
606/lib/libcrypto.so.0.9.6b with symlinks /lib/libssl.so.2 and
607/lib/libcrypto.so.2 respectively).
608
609Please note that we have been advised by Red Hat attempting to recompile the
610openssl rpm with all the cryptography enabled will not work. All other
611packages depend on the original Red Hat supplied openssl package. It is also
612worth noting that due to the way Red Hat supplies its packages, updates to
613openssl on each distribution never change the package version, only the
614build number. For example, on Red Hat 7.1, the latest openssl package has
615version number 0.9.6 and build number 9 even though it contains all the
616relevant updates in packages up to and including 0.9.6b.
617
618A possible way around this is to persuade Red Hat to produce a non-US
619version of Red Hat Linux.
620
621FYI: Patent numbers and expiry dates of US patents:
622MDC-2: 4,908,861 13/03/2007
623IDEA: 5,214,703 25/05/2010
624RC5: 5,724,428 03/03/2015
625
626
627* Why does the OpenSSL compilation fail on MacOS X?
628
629If the failure happens when trying to build the "openssl" binary, with
630a large number of undefined symbols, it's very probable that you have
631OpenSSL 0.9.6b delivered with the operating system (you can find out by
632running '/usr/bin/openssl version') and that you were trying to build
633OpenSSL 0.9.7 or newer. The problem is that the loader ('ld') in
634MacOS X has a misfeature that's quite difficult to go around.
635Look in the file PROBLEMS for a more detailed explanation and for possible
636solutions.
637
638
639* Why does the OpenSSL test suite fail on MacOS X?
640
641If the failure happens when running 'make test' and the RC4 test fails,
642it's very probable that you have OpenSSL 0.9.6b delivered with the
643operating system (you can find out by running '/usr/bin/openssl version')
644and that you were trying to build OpenSSL 0.9.6d. The problem is that
645the loader ('ld') in MacOS X has a misfeature that's quite difficult to
646go around and has linked the programs "openssl" and the test programs
647with /usr/lib/libcrypto.dylib and /usr/lib/libssl.dylib instead of the
648libraries you just built.
649Look in the file PROBLEMS for a more detailed explanation and for possible
650solutions.
651
652* Why does the OpenSSL test suite fail in BN_sqr test [on a 64-bit platform]?
653
654Failure in BN_sqr test is most likely caused by a failure to configure the
655toolkit for current platform or lack of support for the platform in question.
656Run './config -t' and './apps/openssl version -p'. Do these platform
657identifiers match? If they don't, then you most likely failed to run
658./config and you're hereby advised to do so before filing a bug report.
659If ./config itself fails to run, then it's most likely problem with your
660local environment and you should turn to your system administrator (or
661similar). If identifiers match (and/or no alternative identifier is
662suggested by ./config script), then the platform is unsupported. There might
663or might not be a workaround. Most notably on SPARC64 platforms with GNU
664C compiler you should be able to produce a working build by running
665'./config -m32'. I understand that -m32 might not be what you want/need,
666but the build should be operational. For further details turn to
667<openssl-dev@openssl.org>.
668
669* Why does OpenBSD-i386 build fail on des-586.s with "Unimplemented segment type"?
670
671As of 0.9.7 assembler routines were overhauled for position independence
672of the machine code, which is essential for shared library support. For
673some reason OpenBSD is equipped with an out-of-date GNU assembler which
674finds the new code offensive. To work around the problem, configure with
675no-asm (and sacrifice a great deal of performance) or patch your assembler
676according to <URL: http://www.openssl.org/~appro/gas-1.92.3.OpenBSD.patch>.
677For your convenience a pre-compiled replacement binary is provided at
678<URL: http://www.openssl.org/~appro/gas-1.92.3.static.aout.bin>.
679Reportedly elder *BSD a.out platforms also suffer from this problem and
680remedy should be same. Provided binary is statically linked and should be
681working across wider range of *BSD branches, not just OpenBSD.
682
683* Why does the OpenSSL test suite fail in sha512t on x86 CPU?
684
685If the test program in question fails withs SIGILL, Illegal Instruction
686exception, then you more than likely to run SSE2-capable CPU, such as
687Intel P4, under control of kernel which does not support SSE2
688instruction extentions. See accompanying INSTALL file and
689OPENSSL_ia32cap(3) documentation page for further information.
690
691* Why does compiler fail to compile sha512.c?
692
693OpenSSL SHA-512 implementation depends on compiler support for 64-bit
694integer type. Few elder compilers [ULTRIX cc, SCO compiler to mention a
695couple] lack support for this and therefore are incapable of compiling
696the module in question. The recommendation is to disable SHA-512 by
697adding no-sha512 to ./config [or ./Configure] command line. Another
698possible alternative might be to switch to GCC.
699
700* Test suite still fails, what to do?
701
702Another common reason for failure to complete some particular test is
703simply bad code generated by a buggy component in toolchain or deficiency
704in run-time environment. There are few cases documented in PROBLEMS file,
705consult it for possible workaround before you beat the drum. Even if you
706don't find solution or even mention there, do reserve for possibility of
707a compiler bug. Compiler bugs might appear in rather bizarre ways, they
708never make sense, and tend to emerge when you least expect them. In order
709to identify one, drop optimization level, e.g. by editing CFLAG line in
710top-level Makefile, recompile and re-run the test.
711
712[PROG] ========================================================================
713
714* Is OpenSSL thread-safe?
715
716Yes (with limitations: an SSL connection may not concurrently be used
717by multiple threads). On Windows and many Unix systems, OpenSSL
718automatically uses the multi-threaded versions of the standard
719libraries. If your platform is not one of these, consult the INSTALL
720file.
721
722Multi-threaded applications must provide two callback functions to
723OpenSSL by calling CRYPTO_set_locking_callback() and
724CRYPTO_set_id_callback(), for all versions of OpenSSL up to and
725including 0.9.8[abc...]. As of version 1.0.0, CRYPTO_set_id_callback()
726and associated APIs are deprecated by CRYPTO_THREADID_set_callback()
727and friends. This is described in the threads(3) manpage.
728
729* I've compiled a program under Windows and it crashes: why?
730
731This is usually because you've missed the comment in INSTALL.W32.
732Your application must link against the same version of the Win32
733C-Runtime against which your openssl libraries were linked. The
734default version for OpenSSL is /MD - "Multithreaded DLL".
735
736If you are using Microsoft Visual C++'s IDE (Visual Studio), in
737many cases, your new project most likely defaulted to "Debug
738Singlethreaded" - /ML. This is NOT interchangeable with /MD and your
739program will crash, typically on the first BIO related read or write
740operation.
741
742For each of the six possible link stage configurations within Win32,
743your application must link against the same by which OpenSSL was
744built. If you are using MS Visual C++ (Studio) this can be changed
745by:
746
747 1. Select Settings... from the Project Menu.
748 2. Select the C/C++ Tab.
749 3. Select "Code Generation from the "Category" drop down list box
750 4. Select the Appropriate library (see table below) from the "Use
751 run-time library" drop down list box. Perform this step for both
752 your debug and release versions of your application (look at the
753 top left of the settings panel to change between the two)
754
755 Single Threaded /ML - MS VC++ often defaults to
756 this for the release
757 version of a new project.
758 Debug Single Threaded /MLd - MS VC++ often defaults to
759 this for the debug version
760 of a new project.
761 Multithreaded /MT
762 Debug Multithreaded /MTd
763 Multithreaded DLL /MD - OpenSSL defaults to this.
764 Debug Multithreaded DLL /MDd
765
766Note that debug and release libraries are NOT interchangeable. If you
767built OpenSSL with /MD your application must use /MD and cannot use /MDd.
768
769As per 0.9.8 the above limitation is eliminated for .DLLs. OpenSSL
770.DLLs compiled with some specific run-time option [we insist on the
771default /MD] can be deployed with application compiled with different
772option or even different compiler. But there is a catch! Instead of
773re-compiling OpenSSL toolkit, as you would have to with prior versions,
774you have to compile small C snippet with compiler and/or options of
775your choice. The snippet gets installed as
776<install-root>/include/openssl/applink.c and should be either added to
777your application project or simply #include-d in one [and only one]
778of your application source files. Failure to link this shim module
779into your application manifests itself as fatal "no OPENSSL_Applink"
780run-time error. An explicit reminder is due that in this situation
781[mixing compiler options] it is as important to add CRYPTO_malloc_init
782prior first call to OpenSSL.
783
784* How do I read or write a DER encoded buffer using the ASN1 functions?
785
786You have two options. You can either use a memory BIO in conjunction
787with the i2d_*_bio() or d2i_*_bio() functions or you can use the
788i2d_*(), d2i_*() functions directly. Since these are often the
789cause of grief here are some code fragments using PKCS7 as an example:
790
791 unsigned char *buf, *p;
792 int len;
793
794 len = i2d_PKCS7(p7, NULL);
795 buf = OPENSSL_malloc(len); /* or Malloc, error checking omitted */
796 p = buf;
797 i2d_PKCS7(p7, &p);
798
799At this point buf contains the len bytes of the DER encoding of
800p7.
801
802The opposite assumes we already have len bytes in buf:
803
804 unsigned char *p;
805 p = buf;
806 p7 = d2i_PKCS7(NULL, &p, len);
807
808At this point p7 contains a valid PKCS7 structure of NULL if an error
809occurred. If an error occurred ERR_print_errors(bio) should give more
810information.
811
812The reason for the temporary variable 'p' is that the ASN1 functions
813increment the passed pointer so it is ready to read or write the next
814structure. This is often a cause of problems: without the temporary
815variable the buffer pointer is changed to point just after the data
816that has been read or written. This may well be uninitialized data
817and attempts to free the buffer will have unpredictable results
818because it no longer points to the same address.
819
820
821* OpenSSL uses DER but I need BER format: does OpenSSL support BER?
822
823The short answer is yes, because DER is a special case of BER and OpenSSL
824ASN1 decoders can process BER.
825
826The longer answer is that ASN1 structures can be encoded in a number of
827different ways. One set of ways is the Basic Encoding Rules (BER) with various
828permissible encodings. A restriction of BER is the Distinguished Encoding
829Rules (DER): these uniquely specify how a given structure is encoded.
830
831Therefore, because DER is a special case of BER, DER is an acceptable encoding
832for BER.
833
834
835* I've tried using <M_some_evil_pkcs12_macro> and I get errors why?
836
837This usually happens when you try compiling something using the PKCS#12
838macros with a C++ compiler. There is hardly ever any need to use the
839PKCS#12 macros in a program, it is much easier to parse and create
840PKCS#12 files using the PKCS12_parse() and PKCS12_create() functions
841documented in doc/openssl.txt and with examples in demos/pkcs12. The
842'pkcs12' application has to use the macros because it prints out
843debugging information.
844
845
846* I've called <some function> and it fails, why?
847
848Before submitting a report or asking in one of the mailing lists, you
849should try to determine the cause. In particular, you should call
850ERR_print_errors() or ERR_print_errors_fp() after the failed call
851and see if the message helps. Note that the problem may occur earlier
852than you think -- you should check for errors after every call where
853it is possible, otherwise the actual problem may be hidden because
854some OpenSSL functions clear the error state.
855
856
857* I just get a load of numbers for the error output, what do they mean?
858
859The actual format is described in the ERR_print_errors() manual page.
860You should call the function ERR_load_crypto_strings() before hand and
861the message will be output in text form. If you can't do this (for example
862it is a pre-compiled binary) you can use the errstr utility on the error
863code itself (the hex digits after the second colon).
864
865
866* Why do I get errors about unknown algorithms?
867
868The cause is forgetting to load OpenSSL's table of algorithms with
869OpenSSL_add_all_algorithms(). See the manual page for more information. This
870can cause several problems such as being unable to read in an encrypted
871PEM file, unable to decrypt a PKCS#12 file or signature failure when
872verifying certificates.
873
874* Why can't the OpenSSH configure script detect OpenSSL?
875
876Several reasons for problems with the automatic detection exist.
877OpenSSH requires at least version 0.9.5a of the OpenSSL libraries.
878Sometimes the distribution has installed an older version in the system
879locations that is detected instead of a new one installed. The OpenSSL
880library might have been compiled for another CPU or another mode (32/64 bits).
881Permissions might be wrong.
882
883The general answer is to check the config.log file generated when running
884the OpenSSH configure script. It should contain the detailed information
885on why the OpenSSL library was not detected or considered incompatible.
886
887
888* Can I use OpenSSL's SSL library with non-blocking I/O?
889
890Yes; make sure to read the SSL_get_error(3) manual page!
891
892A pitfall to avoid: Don't assume that SSL_read() will just read from
893the underlying transport or that SSL_write() will just write to it --
894it is also possible that SSL_write() cannot do any useful work until
895there is data to read, or that SSL_read() cannot do anything until it
896is possible to send data. One reason for this is that the peer may
897request a new TLS/SSL handshake at any time during the protocol,
898requiring a bi-directional message exchange; both SSL_read() and
899SSL_write() will try to continue any pending handshake.
900
901
902* Why doesn't my server application receive a client certificate?
903
904Due to the TLS protocol definition, a client will only send a certificate,
905if explicitly asked by the server. Use the SSL_VERIFY_PEER flag of the
906SSL_CTX_set_verify() function to enable the use of client certificates.
907
908
909* Why does compilation fail due to an undefined symbol NID_uniqueIdentifier?
910
911For OpenSSL 0.9.7 the OID table was extended and corrected. In earlier
912versions, uniqueIdentifier was incorrectly used for X.509 certificates.
913The correct name according to RFC2256 (LDAP) is x500UniqueIdentifier.
914Change your code to use the new name when compiling against OpenSSL 0.9.7.
915
916
917* I think I've detected a memory leak, is this a bug?
918
919In most cases the cause of an apparent memory leak is an OpenSSL internal table
920that is allocated when an application starts up. Since such tables do not grow
921in size over time they are harmless.
922
923These internal tables can be freed up when an application closes using various
924functions. Currently these include following:
925
926Thread-local cleanup functions:
927
928 ERR_remove_state()
929
930Application-global cleanup functions that are aware of usage (and therefore
931thread-safe):
932
933 ENGINE_cleanup() and CONF_modules_unload()
934
935"Brutal" (thread-unsafe) Application-global cleanup functions:
936
937 ERR_free_strings(), EVP_cleanup() and CRYPTO_cleanup_all_ex_data().
938
939
940* Why does Valgrind complain about the use of uninitialized data?
941
942When OpenSSL's PRNG routines are called to generate random numbers the supplied
943buffer contents are mixed into the entropy pool: so it technically does not
944matter whether the buffer is initialized at this point or not. Valgrind (and
945other test tools) will complain about this. When using Valgrind, make sure the
946OpenSSL library has been compiled with the PURIFY macro defined (-DPURIFY)
947to get rid of these warnings.
948
949
950* Why doesn't a memory BIO work when a file does?
951
952This can occur in several cases for example reading an S/MIME email message.
953The reason is that a memory BIO can do one of two things when all the data
954has been read from it.
955
956The default behaviour is to indicate that no more data is available and that
957the call should be retried, this is to allow the application to fill up the BIO
958again if necessary.
959
960Alternatively it can indicate that no more data is available and that EOF has
961been reached.
962
963If a memory BIO is to behave in the same way as a file this second behaviour
964is needed. This must be done by calling:
965
966 BIO_set_mem_eof_return(bio, 0);
967
968See the manual pages for more details.
969
970
971* Where are the declarations and implementations of d2i_X509() etc?
972
973These are defined and implemented by macros of the form:
974
975
976 DECLARE_ASN1_FUNCTIONS(X509) and IMPLEMENT_ASN1_FUNCTIONS(X509)
977
978The implementation passes an ASN1 "template" defining the structure into an
979ASN1 interpreter using generalised functions such as ASN1_item_d2i().
980
981
982===============================================================================