Import OpenSSL 0.9.8h.
[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?
2e6ca3d0 35* How can I set up a bundle of commercial root CA certificates?
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36
37[BUILD] Questions about building and testing OpenSSL
38
39* Why does the linker complain about undefined symbols?
40* Why does the OpenSSL test fail with "bc: command not found"?
41* Why does the OpenSSL test fail with "bc: 1 no implemented"?
42* Why does the OpenSSL test fail with "bc: stack empty"?
43* Why does the OpenSSL compilation fail on Alpha Tru64 Unix?
44* Why does the OpenSSL compilation fail with "ar: command not found"?
45* Why does the OpenSSL compilation fail on Win32 with VC++?
46* What is special about OpenSSL on Redhat?
47* Why does the OpenSSL compilation fail on MacOS X?
48* Why does the OpenSSL test suite fail on MacOS X?
49* Why does the OpenSSL test suite fail in BN_sqr test [on a 64-bit platform]?
50* Why does OpenBSD-i386 build fail on des-586.s with "Unimplemented segment type"?
51* Why does the OpenSSL test suite fail in sha512t on x86 CPU?
52* Why does compiler fail to compile sha512.c?
74093195 53* Test suite still fails, what to do?
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54
55[PROG] Questions about programming with OpenSSL
56
57* Is OpenSSL thread-safe?
58* I've compiled a program under Windows and it crashes: why?
59* How do I read or write a DER encoded buffer using the ASN1 functions?
60* OpenSSL uses DER but I need BER format: does OpenSSL support BER?
61* I've tried using <M_some_evil_pkcs12_macro> and I get errors why?
62* I've called <some function> and it fails, why?
63* I just get a load of numbers for the error output, what do they mean?
64* Why do I get errors about unknown algorithms?
65* Why can't the OpenSSH configure script detect OpenSSL?
66* Can I use OpenSSL's SSL library with non-blocking I/O?
67* Why doesn't my server application receive a client certificate?
68* Why does compilation fail due to an undefined symbol NID_uniqueIdentifier?
69* I think I've detected a memory leak, is this a bug?
e6bc27f5 70* Why does Valgrind complain about the use of uninitialized data?
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71
72===============================================================================
73
74[MISC] ========================================================================
75
76* Which is the current version of OpenSSL?
77
78The current version is available from <URL: http://www.openssl.org>.
2e6ca3d0 79OpenSSL 0.9.8h was released on May 28th, 2008.
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80
81In addition to the current stable release, you can also access daily
82snapshots of the OpenSSL development version at <URL:
83ftp://ftp.openssl.org/snapshot/>, or get it by anonymous CVS access.
84
85
86* Where is the documentation?
87
88OpenSSL is a library that provides cryptographic functionality to
89applications such as secure web servers. Be sure to read the
90documentation of the application you want to use. The INSTALL file
91explains how to install this library.
92
93OpenSSL includes a command line utility that can be used to perform a
94variety of cryptographic functions. It is described in the openssl(1)
95manpage. Documentation for developers is currently being written. A
96few manual pages already are available; overviews over libcrypto and
97libssl are given in the crypto(3) and ssl(3) manpages.
98
99The OpenSSL manpages are installed in /usr/local/ssl/man/ (or a
100different directory if you specified one as described in INSTALL).
101In addition, you can read the most current versions at
102<URL: http://www.openssl.org/docs/>.
103
104For information on parts of libcrypto that are not yet documented, you
105might want to read Ariel Glenn's documentation on SSLeay 0.9, OpenSSL's
106predecessor, at <URL: http://www.columbia.edu/~ariel/ssleay/>. Much
107of this still applies to OpenSSL.
108
109There is some documentation about certificate extensions and PKCS#12
110in doc/openssl.txt
111
112The original SSLeay documentation is included in OpenSSL as
113doc/ssleay.txt. It may be useful when none of the other resources
114help, but please note that it reflects the obsolete version SSLeay
1150.6.6.
116
117
118* How can I contact the OpenSSL developers?
119
120The README file describes how to submit bug reports and patches to
121OpenSSL. Information on the OpenSSL mailing lists is available from
122<URL: http://www.openssl.org>.
123
124
125* Where can I get a compiled version of OpenSSL?
126
127You can finder pointers to binary distributions in
128http://www.openssl.org/related/binaries.html .
129
130Some applications that use OpenSSL are distributed in binary form.
131When using such an application, you don't need to install OpenSSL
132yourself; the application will include the required parts (e.g. DLLs).
133
134If you want to build OpenSSL on a Windows system and you don't have
135a C compiler, read the "Mingw32" section of INSTALL.W32 for information
136on how to obtain and install the free GNU C compiler.
137
138A number of Linux and *BSD distributions include OpenSSL.
139
140
141* Why aren't tools like 'autoconf' and 'libtool' used?
142
143autoconf will probably be used in future OpenSSL versions. If it was
144less Unix-centric, it might have been used much earlier.
145
146* What is an 'engine' version?
147
148With version 0.9.6 OpenSSL was extended to interface to external crypto
149hardware. This was realized in a special release '0.9.6-engine'. With
150version 0.9.7 the changes were merged into the main development line,
151so that the special release is no longer necessary.
152
153* How do I check the authenticity of the OpenSSL distribution?
154
155We provide MD5 digests and ASC signatures of each tarball.
156Use MD5 to check that a tarball from a mirror site is identical:
157
158 md5sum TARBALL | awk '{print $1;}' | cmp - TARBALL.md5
159
160You can check authenticity using pgp or gpg. You need the OpenSSL team
161member public key used to sign it (download it from a key server, see a
162list of keys at <URL: http://www.openssl.org/about/>). Then
163just do:
164
165 pgp TARBALL.asc
166
167[LEGAL] =======================================================================
168
169* Do I need patent licenses to use OpenSSL?
170
171The patents section of the README file lists patents that may apply to
172you if you want to use OpenSSL. For information on intellectual
173property rights, please consult a lawyer. The OpenSSL team does not
174offer legal advice.
175
176You can configure OpenSSL so as not to use IDEA, MDC2 and RC5 by using
177 ./config no-idea no-mdc2 no-rc5
178
179
180* Can I use OpenSSL with GPL software?
181
182On many systems including the major Linux and BSD distributions, yes (the
183GPL does not place restrictions on using libraries that are part of the
184normal operating system distribution).
185
186On other systems, the situation is less clear. Some GPL software copyright
187holders claim that you infringe on their rights if you use OpenSSL with
188their software on operating systems that don't normally include OpenSSL.
189
190If you develop open source software that uses OpenSSL, you may find it
191useful to choose an other license than the GPL, or state explicitly that
192"This program is released under the GPL with the additional exemption that
193compiling, linking, and/or using OpenSSL is allowed." If you are using
194GPL software developed by others, you may want to ask the copyright holder
195for permission to use their software with OpenSSL.
196
197
198[USER] ========================================================================
199
200* Why do I get a "PRNG not seeded" error message?
201
202Cryptographic software needs a source of unpredictable data to work
203correctly. Many open source operating systems provide a "randomness
204device" (/dev/urandom or /dev/random) that serves this purpose.
205All OpenSSL versions try to use /dev/urandom by default; starting with
206version 0.9.7, OpenSSL also tries /dev/random if /dev/urandom is not
207available.
208
209On other systems, applications have to call the RAND_add() or
210RAND_seed() function with appropriate data before generating keys or
211performing public key encryption. (These functions initialize the
212pseudo-random number generator, PRNG.) Some broken applications do
213not do this. As of version 0.9.5, the OpenSSL functions that need
214randomness report an error if the random number generator has not been
215seeded with at least 128 bits of randomness. If this error occurs and
216is not discussed in the documentation of the application you are
217using, please contact the author of that application; it is likely
218that it never worked correctly. OpenSSL 0.9.5 and later make the
219error visible by refusing to perform potentially insecure encryption.
220
221If you are using Solaris 8, you can add /dev/urandom and /dev/random
222devices by installing patch 112438 (Sparc) or 112439 (x86), which are
223available via the Patchfinder at <URL: http://sunsolve.sun.com>
224(Solaris 9 includes these devices by default). For /dev/random support
225for earlier Solaris versions, see Sun's statement at
226<URL: http://sunsolve.sun.com/pub-cgi/retrieve.pl?doc=fsrdb/27606&zone_32=SUNWski>
227(the SUNWski package is available in patch 105710).
228
229On systems without /dev/urandom and /dev/random, it is a good idea to
230use the Entropy Gathering Demon (EGD); see the RAND_egd() manpage for
231details. Starting with version 0.9.7, OpenSSL will automatically look
232for an EGD socket at /var/run/egd-pool, /dev/egd-pool, /etc/egd-pool and
233/etc/entropy.
234
235Most components of the openssl command line utility automatically try
236to seed the random number generator from a file. The name of the
237default seeding file is determined as follows: If environment variable
238RANDFILE is set, then it names the seeding file. Otherwise if
239environment variable HOME is set, then the seeding file is $HOME/.rnd.
240If neither RANDFILE nor HOME is set, versions up to OpenSSL 0.9.6 will
241use file .rnd in the current directory while OpenSSL 0.9.6a uses no
242default seeding file at all. OpenSSL 0.9.6b and later will behave
243similarly to 0.9.6a, but will use a default of "C:\" for HOME on
244Windows systems if the environment variable has not been set.
245
246If the default seeding file does not exist or is too short, the "PRNG
247not seeded" error message may occur.
248
249The openssl command line utility will write back a new state to the
250default seeding file (and create this file if necessary) unless
251there was no sufficient seeding.
252
253Pointing $RANDFILE to an Entropy Gathering Daemon socket does not work.
254Use the "-rand" option of the OpenSSL command line tools instead.
255The $RANDFILE environment variable and $HOME/.rnd are only used by the
256OpenSSL command line tools. Applications using the OpenSSL library
257provide their own configuration options to specify the entropy source,
258please check out the documentation coming the with application.
259
260
261* Why do I get an "unable to write 'random state'" error message?
262
263
264Sometimes the openssl command line utility does not abort with
265a "PRNG not seeded" error message, but complains that it is
266"unable to write 'random state'". This message refers to the
267default seeding file (see previous answer). A possible reason
268is that no default filename is known because neither RANDFILE
269nor HOME is set. (Versions up to 0.9.6 used file ".rnd" in the
270current directory in this case, but this has changed with 0.9.6a.)
271
272
273* How do I create certificates or certificate requests?
274
275Check out the CA.pl(1) manual page. This provides a simple wrapper round
276the 'req', 'verify', 'ca' and 'pkcs12' utilities. For finer control check
277out the manual pages for the individual utilities and the certificate
278extensions documentation (currently in doc/openssl.txt).
279
280
281* Why can't I create certificate requests?
282
283You typically get the error:
284
285 unable to find 'distinguished_name' in config
286 problems making Certificate Request
287
288This is because it can't find the configuration file. Check out the
289DIAGNOSTICS section of req(1) for more information.
290
291
292* Why does <SSL program> fail with a certificate verify error?
293
294This problem is usually indicated by log messages saying something like
295"unable to get local issuer certificate" or "self signed certificate".
296When a certificate is verified its root CA must be "trusted" by OpenSSL
297this typically means that the CA certificate must be placed in a directory
298or file and the relevant program configured to read it. The OpenSSL program
299'verify' behaves in a similar way and issues similar error messages: check
300the verify(1) program manual page for more information.
301
302
303* Why can I only use weak ciphers when I connect to a server using OpenSSL?
304
305This is almost certainly because you are using an old "export grade" browser
306which only supports weak encryption. Upgrade your browser to support 128 bit
307ciphers.
308
309
310* How can I create DSA certificates?
311
312Check the CA.pl(1) manual page for a DSA certificate example.
313
314
315* Why can't I make an SSL connection to a server using a DSA certificate?
316
317Typically you'll see a message saying there are no shared ciphers when
318the same setup works fine with an RSA certificate. There are two possible
319causes. The client may not support connections to DSA servers most web
320browsers (including Netscape and MSIE) only support connections to servers
321supporting RSA cipher suites. The other cause is that a set of DH parameters
322has not been supplied to the server. DH parameters can be created with the
323dhparam(1) command and loaded using the SSL_CTX_set_tmp_dh() for example:
324check the source to s_server in apps/s_server.c for an example.
325
326
327* How can I remove the passphrase on a private key?
328
329Firstly you should be really *really* sure you want to do this. Leaving
330a private key unencrypted is a major security risk. If you decide that
331you do have to do this check the EXAMPLES sections of the rsa(1) and
332dsa(1) manual pages.
333
334
335* Why can't I use OpenSSL certificates with SSL client authentication?
336
337What will typically happen is that when a server requests authentication
338it will either not include your certificate or tell you that you have
339no client certificates (Netscape) or present you with an empty list box
340(MSIE). The reason for this is that when a server requests a client
341certificate it includes a list of CAs names which it will accept. Browsers
342will only let you select certificates from the list on the grounds that
343there is little point presenting a certificate which the server will
344reject.
345
346The solution is to add the relevant CA certificate to your servers "trusted
347CA list". How you do this depends on the server software in uses. You can
348print out the servers list of acceptable CAs using the OpenSSL s_client tool:
349
350openssl s_client -connect www.some.host:443 -prexit
351
352If your server only requests certificates on certain URLs then you may need
353to manually issue an HTTP GET command to get the list when s_client connects:
354
355GET /some/page/needing/a/certificate.html
356
357If your CA does not appear in the list then this confirms the problem.
358
359
360* Why does my browser give a warning about a mismatched hostname?
361
362Browsers expect the server's hostname to match the value in the commonName
363(CN) field of the certificate. If it does not then you get a warning.
364
365
366* How do I install a CA certificate into a browser?
367
368The usual way is to send the DER encoded certificate to the browser as
369MIME type application/x-x509-ca-cert, for example by clicking on an appropriate
370link. On MSIE certain extensions such as .der or .cacert may also work, or you
371can import the certificate using the certificate import wizard.
372
373You can convert a certificate to DER form using the command:
374
375openssl x509 -in ca.pem -outform DER -out ca.der
376
377Occasionally someone suggests using a command such as:
378
379openssl pkcs12 -export -out cacert.p12 -in cacert.pem -inkey cakey.pem
380
381DO NOT DO THIS! This command will give away your CAs private key and
382reduces its security to zero: allowing anyone to forge certificates in
383whatever name they choose.
384
385* Why is OpenSSL x509 DN output not conformant to RFC2253?
386
387The ways to print out the oneline format of the DN (Distinguished Name) have
388been extended in version 0.9.7 of OpenSSL. Using the new X509_NAME_print_ex()
389interface, the "-nameopt" option could be introduded. See the manual
390page of the "openssl x509" commandline tool for details. The old behaviour
391has however been left as default for the sake of compatibility.
392
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393* What is a "128 bit certificate"? Can I create one with OpenSSL?
394
395The term "128 bit certificate" is a highly misleading marketing term. It does
396*not* refer to the size of the public key in the certificate! A certificate
397containing a 128 bit RSA key would have negligible security.
398
399There were various other names such as "magic certificates", "SGC
400certificates", "step up certificates" etc.
401
402You can't generally create such a certificate using OpenSSL but there is no
403need to any more. Nowadays web browsers using unrestricted strong encryption
404are generally available.
405
406When there were tight export restrictions on the export of strong encryption
407software from the US only weak encryption algorithms could be freely exported
408(initially 40 bit and then 56 bit). It was widely recognised that this was
409inadequate. A relaxation the rules allowed the use of strong encryption but
410only to an authorised server.
411
412Two slighly different techniques were developed to support this, one used by
413Netscape was called "step up", the other used by MSIE was called "Server Gated
414Cryptography" (SGC). When a browser initially connected to a server it would
415check to see if the certificate contained certain extensions and was issued by
416an authorised authority. If these test succeeded it would reconnect using
417strong encryption.
418
419Only certain (initially one) certificate authorities could issue the
420certificates and they generally cost more than ordinary certificates.
421
422Although OpenSSL can create certificates containing the appropriate extensions
423the certificate would not come from a permitted authority and so would not
424be recognized.
425
426The export laws were later changed to allow almost unrestricted use of strong
427encryption so these certificates are now obsolete.
428
429
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430* How can I set up a bundle of commercial root CA certificates?
431
432The OpenSSL software is shipped without any root CA certificate as the
433OpenSSL project does not have any policy on including or excluding
434any specific CA and does not intend to set up such a policy. Deciding
435about which CAs to support is up to application developers or
436administrators.
437
438Other projects do have other policies so you can for example extract the CA
439bundle used by Mozilla and/or modssl as described in this article:
440
441 http://www.mail-archive.com/modssl-users@modssl.org/msg16980.html
442
443
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444[BUILD] =======================================================================
445
446* Why does the linker complain about undefined symbols?
447
448Maybe the compilation was interrupted, and make doesn't notice that
449something is missing. Run "make clean; make".
450
451If you used ./Configure instead of ./config, make sure that you
452selected the right target. File formats may differ slightly between
453OS versions (for example sparcv8/sparcv9, or a.out/elf).
454
455In case you get errors about the following symbols, use the config
456option "no-asm", as described in INSTALL:
457
458 BF_cbc_encrypt, BF_decrypt, BF_encrypt, CAST_cbc_encrypt,
459 CAST_decrypt, CAST_encrypt, RC4, RC5_32_cbc_encrypt, RC5_32_decrypt,
460 RC5_32_encrypt, bn_add_words, bn_div_words, bn_mul_add_words,
461 bn_mul_comba4, bn_mul_comba8, bn_mul_words, bn_sqr_comba4,
462 bn_sqr_comba8, bn_sqr_words, bn_sub_words, des_decrypt3,
463 des_ede3_cbc_encrypt, des_encrypt, des_encrypt2, des_encrypt3,
464 des_ncbc_encrypt, md5_block_asm_host_order, sha1_block_asm_data_order
465
466If none of these helps, you may want to try using the current snapshot.
467If the problem persists, please submit a bug report.
468
469
470* Why does the OpenSSL test fail with "bc: command not found"?
471
472You didn't install "bc", the Unix calculator. If you want to run the
473tests, get GNU bc from ftp://ftp.gnu.org or from your OS distributor.
474
475
476* Why does the OpenSSL test fail with "bc: 1 no implemented"?
477
478On some SCO installations or versions, bc has a bug that gets triggered
479when you run the test suite (using "make test"). The message returned is
480"bc: 1 not implemented".
481
482The best way to deal with this is to find another implementation of bc
483and compile/install it. GNU bc (see http://www.gnu.org/software/software.html
484for download instructions) can be safely used, for example.
485
486
487* Why does the OpenSSL test fail with "bc: stack empty"?
488
489On some DG/ux versions, bc seems to have a too small stack for calculations
490that the OpenSSL bntest throws at it. This gets triggered when you run the
491test suite (using "make test"). The message returned is "bc: stack empty".
492
493The best way to deal with this is to find another implementation of bc
494and compile/install it. GNU bc (see http://www.gnu.org/software/software.html
495for download instructions) can be safely used, for example.
496
497
498* Why does the OpenSSL compilation fail on Alpha Tru64 Unix?
499
500On some Alpha installations running Tru64 Unix and Compaq C, the compilation
501of crypto/sha/sha_dgst.c fails with the message 'Fatal: Insufficient virtual
502memory to continue compilation.' As far as the tests have shown, this may be
503a compiler bug. What happens is that it eats up a lot of resident memory
504to build something, probably a table. The problem is clearly in the
505optimization code, because if one eliminates optimization completely (-O0),
506the compilation goes through (and the compiler consumes about 2MB of resident
507memory instead of 240MB or whatever one's limit is currently).
508
509There are three options to solve this problem:
510
5111. set your current data segment size soft limit higher. Experience shows
512that about 241000 kbytes seems to be enough on an AlphaServer DS10. You do
513this with the command 'ulimit -Sd nnnnnn', where 'nnnnnn' is the number of
514kbytes to set the limit to.
515
5162. If you have a hard limit that is lower than what you need and you can't
517get it changed, you can compile all of OpenSSL with -O0 as optimization
518level. This is however not a very nice thing to do for those who expect to
519get the best result from OpenSSL. A bit more complicated solution is the
520following:
521
522----- snip:start -----
523 make DIRS=crypto SDIRS=sha "`grep '^CFLAG=' Makefile.ssl | \
524 sed -e 's/ -O[0-9] / -O0 /'`"
525 rm `ls crypto/*.o crypto/sha/*.o | grep -v 'sha_dgst\.o'`
526 make
527----- snip:end -----
528
529This will only compile sha_dgst.c with -O0, the rest with the optimization
530level chosen by the configuration process. When the above is done, do the
531test and installation and you're set.
532
5333. Reconfigure the toolkit with no-sha0 option to leave out SHA0. It
534should not be used and is not used in SSL/TLS nor any other recognized
535protocol in either case.
536
537
538* Why does the OpenSSL compilation fail with "ar: command not found"?
539
540Getting this message is quite usual on Solaris 2, because Sun has hidden
541away 'ar' and other development commands in directories that aren't in
542$PATH by default. One of those directories is '/usr/ccs/bin'. The
543quickest way to fix this is to do the following (it assumes you use sh
544or any sh-compatible shell):
545
546----- snip:start -----
547 PATH=${PATH}:/usr/ccs/bin; export PATH
548----- snip:end -----
549
550and then redo the compilation. What you should really do is make sure
551'/usr/ccs/bin' is permanently in your $PATH, for example through your
552'.profile' (again, assuming you use a sh-compatible shell).
553
554
555* Why does the OpenSSL compilation fail on Win32 with VC++?
556
557Sometimes, you may get reports from VC++ command line (cl) that it
558can't find standard include files like stdio.h and other weirdnesses.
559One possible cause is that the environment isn't correctly set up.
560To solve that problem for VC++ versions up to 6, one should run
561VCVARS32.BAT which is found in the 'bin' subdirectory of the VC++
562installation directory (somewhere under 'Program Files'). For VC++
563version 7 (and up?), which is also called VS.NET, the file is called
564VSVARS32.BAT instead.
565This needs to be done prior to running NMAKE, and the changes are only
566valid for the current DOS session.
567
568
569* What is special about OpenSSL on Redhat?
570
571Red Hat Linux (release 7.0 and later) include a preinstalled limited
572version of OpenSSL. For patent reasons, support for IDEA, RC5 and MDC2
573is disabled in this version. The same may apply to other Linux distributions.
574Users may therefore wish to install more or all of the features left out.
575
576To do this you MUST ensure that you do not overwrite the openssl that is in
577/usr/bin on your Red Hat machine. Several packages depend on this file,
578including sendmail and ssh. /usr/local/bin is a good alternative choice. The
579libraries that come with Red Hat 7.0 onwards have different names and so are
580not affected. (eg For Red Hat 7.2 they are /lib/libssl.so.0.9.6b and
581/lib/libcrypto.so.0.9.6b with symlinks /lib/libssl.so.2 and
582/lib/libcrypto.so.2 respectively).
583
584Please note that we have been advised by Red Hat attempting to recompile the
585openssl rpm with all the cryptography enabled will not work. All other
586packages depend on the original Red Hat supplied openssl package. It is also
587worth noting that due to the way Red Hat supplies its packages, updates to
588openssl on each distribution never change the package version, only the
589build number. For example, on Red Hat 7.1, the latest openssl package has
590version number 0.9.6 and build number 9 even though it contains all the
591relevant updates in packages up to and including 0.9.6b.
592
593A possible way around this is to persuade Red Hat to produce a non-US
594version of Red Hat Linux.
595
596FYI: Patent numbers and expiry dates of US patents:
597MDC-2: 4,908,861 13/03/2007
598IDEA: 5,214,703 25/05/2010
599RC5: 5,724,428 03/03/2015
600
601
602* Why does the OpenSSL compilation fail on MacOS X?
603
604If the failure happens when trying to build the "openssl" binary, with
605a large number of undefined symbols, it's very probable that you have
606OpenSSL 0.9.6b delivered with the operating system (you can find out by
607running '/usr/bin/openssl version') and that you were trying to build
608OpenSSL 0.9.7 or newer. The problem is that the loader ('ld') in
609MacOS X has a misfeature that's quite difficult to go around.
610Look in the file PROBLEMS for a more detailed explanation and for possible
611solutions.
612
613
614* Why does the OpenSSL test suite fail on MacOS X?
615
616If the failure happens when running 'make test' and the RC4 test fails,
617it's very probable that you have OpenSSL 0.9.6b delivered with the
618operating system (you can find out by running '/usr/bin/openssl version')
619and that you were trying to build OpenSSL 0.9.6d. The problem is that
620the loader ('ld') in MacOS X has a misfeature that's quite difficult to
621go around and has linked the programs "openssl" and the test programs
622with /usr/lib/libcrypto.dylib and /usr/lib/libssl.dylib instead of the
623libraries you just built.
624Look in the file PROBLEMS for a more detailed explanation and for possible
625solutions.
626
627* Why does the OpenSSL test suite fail in BN_sqr test [on a 64-bit platform]?
628
629Failure in BN_sqr test is most likely caused by a failure to configure the
630toolkit for current platform or lack of support for the platform in question.
631Run './config -t' and './apps/openssl version -p'. Do these platform
632identifiers match? If they don't, then you most likely failed to run
633./config and you're hereby advised to do so before filing a bug report.
634If ./config itself fails to run, then it's most likely problem with your
635local environment and you should turn to your system administrator (or
636similar). If identifiers match (and/or no alternative identifier is
637suggested by ./config script), then the platform is unsupported. There might
638or might not be a workaround. Most notably on SPARC64 platforms with GNU
639C compiler you should be able to produce a working build by running
640'./config -m32'. I understand that -m32 might not be what you want/need,
641but the build should be operational. For further details turn to
642<openssl-dev@openssl.org>.
643
644* Why does OpenBSD-i386 build fail on des-586.s with "Unimplemented segment type"?
645
646As of 0.9.7 assembler routines were overhauled for position independence
647of the machine code, which is essential for shared library support. For
648some reason OpenBSD is equipped with an out-of-date GNU assembler which
649finds the new code offensive. To work around the problem, configure with
650no-asm (and sacrifice a great deal of performance) or patch your assembler
651according to <URL: http://www.openssl.org/~appro/gas-1.92.3.OpenBSD.patch>.
652For your convenience a pre-compiled replacement binary is provided at
653<URL: http://www.openssl.org/~appro/gas-1.92.3.static.aout.bin>.
654Reportedly elder *BSD a.out platforms also suffer from this problem and
655remedy should be same. Provided binary is statically linked and should be
656working across wider range of *BSD branches, not just OpenBSD.
657
658* Why does the OpenSSL test suite fail in sha512t on x86 CPU?
659
660If the test program in question fails withs SIGILL, Illegal Instruction
661exception, then you more than likely to run SSE2-capable CPU, such as
662Intel P4, under control of kernel which does not support SSE2
663instruction extentions. See accompanying INSTALL file and
664OPENSSL_ia32cap(3) documentation page for further information.
665
666* Why does compiler fail to compile sha512.c?
667
668OpenSSL SHA-512 implementation depends on compiler support for 64-bit
669integer type. Few elder compilers [ULTRIX cc, SCO compiler to mention a
670couple] lack support for this and therefore are incapable of compiling
671the module in question. The recommendation is to disable SHA-512 by
672adding no-sha512 to ./config [or ./Configure] command line. Another
673possible alternative might be to switch to GCC.
674
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675* Test suite still fails, what to do?
676
677Another common reason for failure to complete some particular test is
678simply bad code generated by a buggy component in toolchain or deficiency
679in run-time environment. There are few cases documented in PROBLEMS file,
680consult it for possible workaround before you beat the drum. Even if you
681don't find solution or even mention there, do reserve for possibility of
682a compiler bug. Compiler bugs might appear in rather bizarre ways, they
683never make sense, and tend to emerge when you least expect them. In order
684to identify one, drop optimization level, e.g. by editing CFLAG line in
685top-level Makefile, recompile and re-run the test.
686
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687[PROG] ========================================================================
688
689* Is OpenSSL thread-safe?
690
691Yes (with limitations: an SSL connection may not concurrently be used
692by multiple threads). On Windows and many Unix systems, OpenSSL
693automatically uses the multi-threaded versions of the standard
694libraries. If your platform is not one of these, consult the INSTALL
695file.
696
697Multi-threaded applications must provide two callback functions to
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698OpenSSL by calling CRYPTO_set_locking_callback() and
699CRYPTO_set_id_callback(). This is described in the threads(3)
700manpage.
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701
702* I've compiled a program under Windows and it crashes: why?
703
704This is usually because you've missed the comment in INSTALL.W32.
705Your application must link against the same version of the Win32
706C-Runtime against which your openssl libraries were linked. The
707default version for OpenSSL is /MD - "Multithreaded DLL".
708
709If you are using Microsoft Visual C++'s IDE (Visual Studio), in
710many cases, your new project most likely defaulted to "Debug
711Singlethreaded" - /ML. This is NOT interchangeable with /MD and your
712program will crash, typically on the first BIO related read or write
713operation.
714
715For each of the six possible link stage configurations within Win32,
716your application must link against the same by which OpenSSL was
717built. If you are using MS Visual C++ (Studio) this can be changed
718by:
719
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720 1. Select Settings... from the Project Menu.
721 2. Select the C/C++ Tab.
722 3. Select "Code Generation from the "Category" drop down list box
723 4. Select the Appropriate library (see table below) from the "Use
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724 run-time library" drop down list box. Perform this step for both
725 your debug and release versions of your application (look at the
726 top left of the settings panel to change between the two)
727
728 Single Threaded /ML - MS VC++ often defaults to
729 this for the release
730 version of a new project.
731 Debug Single Threaded /MLd - MS VC++ often defaults to
732 this for the debug version
733 of a new project.
734 Multithreaded /MT
735 Debug Multithreaded /MTd
736 Multithreaded DLL /MD - OpenSSL defaults to this.
737 Debug Multithreaded DLL /MDd
738
739Note that debug and release libraries are NOT interchangeable. If you
740built OpenSSL with /MD your application must use /MD and cannot use /MDd.
741
742As per 0.9.8 the above limitation is eliminated for .DLLs. OpenSSL
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744default /MD] can be deployed with application compiled with different
745option or even different compiler. But there is a catch! Instead of
746re-compiling OpenSSL toolkit, as you would have to with prior versions,
747you have to compile small C snippet with compiler and/or options of
748your choice. The snippet gets installed as
749<install-root>/include/openssl/applink.c and should be either added to
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750your application project or simply #include-d in one [and only one]
751of your application source files. Failure to link this shim module
752into your application manifests itself as fatal "no OPENSSL_Applink"
753run-time error. An explicit reminder is due that in this situation
754[mixing compiler options] it is as important to add CRYPTO_malloc_init
755prior first call to OpenSSL.
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756
757* How do I read or write a DER encoded buffer using the ASN1 functions?
758
759You have two options. You can either use a memory BIO in conjunction
760with the i2d_*_bio() or d2i_*_bio() functions or you can use the
761i2d_*(), d2i_*() functions directly. Since these are often the
762cause of grief here are some code fragments using PKCS7 as an example:
763
764 unsigned char *buf, *p;
765 int len;
766
767 len = i2d_PKCS7(p7, NULL);
768 buf = OPENSSL_malloc(len); /* or Malloc, error checking omitted */
769 p = buf;
770 i2d_PKCS7(p7, &p);
771
772At this point buf contains the len bytes of the DER encoding of
773p7.
774
775The opposite assumes we already have len bytes in buf:
776
777 unsigned char *p;
778 p = buf;
779 p7 = d2i_PKCS7(NULL, &p, len);
780
781At this point p7 contains a valid PKCS7 structure of NULL if an error
782occurred. If an error occurred ERR_print_errors(bio) should give more
783information.
784
785The reason for the temporary variable 'p' is that the ASN1 functions
786increment the passed pointer so it is ready to read or write the next
787structure. This is often a cause of problems: without the temporary
788variable the buffer pointer is changed to point just after the data
789that has been read or written. This may well be uninitialized data
790and attempts to free the buffer will have unpredictable results
791because it no longer points to the same address.
792
793
794* OpenSSL uses DER but I need BER format: does OpenSSL support BER?
795
796The short answer is yes, because DER is a special case of BER and OpenSSL
797ASN1 decoders can process BER.
798
799The longer answer is that ASN1 structures can be encoded in a number of
800different ways. One set of ways is the Basic Encoding Rules (BER) with various
801permissible encodings. A restriction of BER is the Distinguished Encoding
802Rules (DER): these uniquely specify how a given structure is encoded.
803
804Therefore, because DER is a special case of BER, DER is an acceptable encoding
805for BER.
806
807
808* I've tried using <M_some_evil_pkcs12_macro> and I get errors why?
809
810This usually happens when you try compiling something using the PKCS#12
811macros with a C++ compiler. There is hardly ever any need to use the
812PKCS#12 macros in a program, it is much easier to parse and create
813PKCS#12 files using the PKCS12_parse() and PKCS12_create() functions
814documented in doc/openssl.txt and with examples in demos/pkcs12. The
815'pkcs12' application has to use the macros because it prints out
816debugging information.
817
818
819* I've called <some function> and it fails, why?
820
821Before submitting a report or asking in one of the mailing lists, you
822should try to determine the cause. In particular, you should call
823ERR_print_errors() or ERR_print_errors_fp() after the failed call
824and see if the message helps. Note that the problem may occur earlier
825than you think -- you should check for errors after every call where
826it is possible, otherwise the actual problem may be hidden because
827some OpenSSL functions clear the error state.
828
829
830* I just get a load of numbers for the error output, what do they mean?
831
832The actual format is described in the ERR_print_errors() manual page.
833You should call the function ERR_load_crypto_strings() before hand and
834the message will be output in text form. If you can't do this (for example
835it is a pre-compiled binary) you can use the errstr utility on the error
836code itself (the hex digits after the second colon).
837
838
839* Why do I get errors about unknown algorithms?
840
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841The cause is forgetting to load OpenSSL's table of algorithms with
842OpenSSL_add_all_algorithms(). See the manual page for more information. This
843can cause several problems such as being unable to read in an encrypted
844PEM file, unable to decrypt a PKCS#12 file or signature failure when
845verifying certificates.
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846
847* Why can't the OpenSSH configure script detect OpenSSL?
848
849Several reasons for problems with the automatic detection exist.
850OpenSSH requires at least version 0.9.5a of the OpenSSL libraries.
851Sometimes the distribution has installed an older version in the system
852locations that is detected instead of a new one installed. The OpenSSL
853library might have been compiled for another CPU or another mode (32/64 bits).
854Permissions might be wrong.
855
856The general answer is to check the config.log file generated when running
857the OpenSSH configure script. It should contain the detailed information
858on why the OpenSSL library was not detected or considered incompatible.
859
860
861* Can I use OpenSSL's SSL library with non-blocking I/O?
862
863Yes; make sure to read the SSL_get_error(3) manual page!
864
865A pitfall to avoid: Don't assume that SSL_read() will just read from
866the underlying transport or that SSL_write() will just write to it --
867it is also possible that SSL_write() cannot do any useful work until
868there is data to read, or that SSL_read() cannot do anything until it
869is possible to send data. One reason for this is that the peer may
870request a new TLS/SSL handshake at any time during the protocol,
871requiring a bi-directional message exchange; both SSL_read() and
872SSL_write() will try to continue any pending handshake.
873
874
875* Why doesn't my server application receive a client certificate?
876
877Due to the TLS protocol definition, a client will only send a certificate,
878if explicitly asked by the server. Use the SSL_VERIFY_PEER flag of the
879SSL_CTX_set_verify() function to enable the use of client certificates.
880
881
882* Why does compilation fail due to an undefined symbol NID_uniqueIdentifier?
883
884For OpenSSL 0.9.7 the OID table was extended and corrected. In earlier
885versions, uniqueIdentifier was incorrectly used for X.509 certificates.
886The correct name according to RFC2256 (LDAP) is x500UniqueIdentifier.
887Change your code to use the new name when compiling against OpenSSL 0.9.7.
888
889
890* I think I've detected a memory leak, is this a bug?
891
892In most cases the cause of an apparent memory leak is an OpenSSL internal table
893that is allocated when an application starts up. Since such tables do not grow
894in size over time they are harmless.
895
896These internal tables can be freed up when an application closes using various
897functions. Currently these include following:
898
899Thread-local cleanup functions:
900
901 ERR_remove_state()
902
903Application-global cleanup functions that are aware of usage (and therefore
904thread-safe):
905
906 ENGINE_cleanup() and CONF_modules_unload()
907
908"Brutal" (thread-unsafe) Application-global cleanup functions:
909
910 ERR_free_strings(), EVP_cleanup() and CRYPTO_cleanup_all_ex_data().
911
912
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913* Why does Valgrind complain about the use of uninitialized data?
914
915When OpenSSL's PRNG routines are called to generate random numbers the supplied
916buffer contents are mixed into the entropy pool: so it technically does not
917matter whether the buffer is initialized at this point or not. Valgrind (and
918other test tools) will complain about this. When using Valgrind, make sure the
919OpenSSL library has been compiled with the PURIFY macro defined (-DPURIFY)
920to get rid of these warnings.
921
922
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923===============================================================================
924