Import OpenSSL-0.9.8g.
[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?
e6bc27f5 69* Why does Valgrind complain about the use of uninitialized data?
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70
71===============================================================================
72
73[MISC] ========================================================================
74
75* Which is the current version of OpenSSL?
76
77The current version is available from <URL: http://www.openssl.org>.
96768186 78OpenSSL 0.9.8g was released on October 19th, 2007.
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79
80In addition to the current stable release, you can also access daily
81snapshots of the OpenSSL development version at <URL:
82ftp://ftp.openssl.org/snapshot/>, or get it by anonymous CVS access.
83
84
85* Where is the documentation?
86
87OpenSSL is a library that provides cryptographic functionality to
88applications such as secure web servers. Be sure to read the
89documentation of the application you want to use. The INSTALL file
90explains how to install this library.
91
92OpenSSL includes a command line utility that can be used to perform a
93variety of cryptographic functions. It is described in the openssl(1)
94manpage. Documentation for developers is currently being written. A
95few manual pages already are available; overviews over libcrypto and
96libssl are given in the crypto(3) and ssl(3) manpages.
97
98The OpenSSL manpages are installed in /usr/local/ssl/man/ (or a
99different directory if you specified one as described in INSTALL).
100In addition, you can read the most current versions at
101<URL: http://www.openssl.org/docs/>.
102
103For information on parts of libcrypto that are not yet documented, you
104might want to read Ariel Glenn's documentation on SSLeay 0.9, OpenSSL's
105predecessor, at <URL: http://www.columbia.edu/~ariel/ssleay/>. Much
106of this still applies to OpenSSL.
107
108There is some documentation about certificate extensions and PKCS#12
109in doc/openssl.txt
110
111The original SSLeay documentation is included in OpenSSL as
112doc/ssleay.txt. It may be useful when none of the other resources
113help, but please note that it reflects the obsolete version SSLeay
1140.6.6.
115
116
117* How can I contact the OpenSSL developers?
118
119The README file describes how to submit bug reports and patches to
120OpenSSL. Information on the OpenSSL mailing lists is available from
121<URL: http://www.openssl.org>.
122
123
124* Where can I get a compiled version of OpenSSL?
125
126You can finder pointers to binary distributions in
127http://www.openssl.org/related/binaries.html .
128
129Some applications that use OpenSSL are distributed in binary form.
130When using such an application, you don't need to install OpenSSL
131yourself; the application will include the required parts (e.g. DLLs).
132
133If you want to build OpenSSL on a Windows system and you don't have
134a C compiler, read the "Mingw32" section of INSTALL.W32 for information
135on how to obtain and install the free GNU C compiler.
136
137A number of Linux and *BSD distributions include OpenSSL.
138
139
140* Why aren't tools like 'autoconf' and 'libtool' used?
141
142autoconf will probably be used in future OpenSSL versions. If it was
143less Unix-centric, it might have been used much earlier.
144
145* What is an 'engine' version?
146
147With version 0.9.6 OpenSSL was extended to interface to external crypto
148hardware. This was realized in a special release '0.9.6-engine'. With
149version 0.9.7 the changes were merged into the main development line,
150so that the special release is no longer necessary.
151
152* How do I check the authenticity of the OpenSSL distribution?
153
154We provide MD5 digests and ASC signatures of each tarball.
155Use MD5 to check that a tarball from a mirror site is identical:
156
157 md5sum TARBALL | awk '{print $1;}' | cmp - TARBALL.md5
158
159You can check authenticity using pgp or gpg. You need the OpenSSL team
160member public key used to sign it (download it from a key server, see a
161list of keys at <URL: http://www.openssl.org/about/>). Then
162just do:
163
164 pgp TARBALL.asc
165
166[LEGAL] =======================================================================
167
168* Do I need patent licenses to use OpenSSL?
169
170The patents section of the README file lists patents that may apply to
171you if you want to use OpenSSL. For information on intellectual
172property rights, please consult a lawyer. The OpenSSL team does not
173offer legal advice.
174
175You can configure OpenSSL so as not to use IDEA, MDC2 and RC5 by using
176 ./config no-idea no-mdc2 no-rc5
177
178
179* Can I use OpenSSL with GPL software?
180
181On many systems including the major Linux and BSD distributions, yes (the
182GPL does not place restrictions on using libraries that are part of the
183normal operating system distribution).
184
185On other systems, the situation is less clear. Some GPL software copyright
186holders claim that you infringe on their rights if you use OpenSSL with
187their software on operating systems that don't normally include OpenSSL.
188
189If you develop open source software that uses OpenSSL, you may find it
190useful to choose an other license than the GPL, or state explicitly that
191"This program is released under the GPL with the additional exemption that
192compiling, linking, and/or using OpenSSL is allowed." If you are using
193GPL software developed by others, you may want to ask the copyright holder
194for permission to use their software with OpenSSL.
195
196
197[USER] ========================================================================
198
199* Why do I get a "PRNG not seeded" error message?
200
201Cryptographic software needs a source of unpredictable data to work
202correctly. Many open source operating systems provide a "randomness
203device" (/dev/urandom or /dev/random) that serves this purpose.
204All OpenSSL versions try to use /dev/urandom by default; starting with
205version 0.9.7, OpenSSL also tries /dev/random if /dev/urandom is not
206available.
207
208On other systems, applications have to call the RAND_add() or
209RAND_seed() function with appropriate data before generating keys or
210performing public key encryption. (These functions initialize the
211pseudo-random number generator, PRNG.) Some broken applications do
212not do this. As of version 0.9.5, the OpenSSL functions that need
213randomness report an error if the random number generator has not been
214seeded with at least 128 bits of randomness. If this error occurs and
215is not discussed in the documentation of the application you are
216using, please contact the author of that application; it is likely
217that it never worked correctly. OpenSSL 0.9.5 and later make the
218error visible by refusing to perform potentially insecure encryption.
219
220If you are using Solaris 8, you can add /dev/urandom and /dev/random
221devices by installing patch 112438 (Sparc) or 112439 (x86), which are
222available via the Patchfinder at <URL: http://sunsolve.sun.com>
223(Solaris 9 includes these devices by default). For /dev/random support
224for earlier Solaris versions, see Sun's statement at
225<URL: http://sunsolve.sun.com/pub-cgi/retrieve.pl?doc=fsrdb/27606&zone_32=SUNWski>
226(the SUNWski package is available in patch 105710).
227
228On systems without /dev/urandom and /dev/random, it is a good idea to
229use the Entropy Gathering Demon (EGD); see the RAND_egd() manpage for
230details. Starting with version 0.9.7, OpenSSL will automatically look
231for an EGD socket at /var/run/egd-pool, /dev/egd-pool, /etc/egd-pool and
232/etc/entropy.
233
234Most components of the openssl command line utility automatically try
235to seed the random number generator from a file. The name of the
236default seeding file is determined as follows: If environment variable
237RANDFILE is set, then it names the seeding file. Otherwise if
238environment variable HOME is set, then the seeding file is $HOME/.rnd.
239If neither RANDFILE nor HOME is set, versions up to OpenSSL 0.9.6 will
240use file .rnd in the current directory while OpenSSL 0.9.6a uses no
241default seeding file at all. OpenSSL 0.9.6b and later will behave
242similarly to 0.9.6a, but will use a default of "C:\" for HOME on
243Windows systems if the environment variable has not been set.
244
245If the default seeding file does not exist or is too short, the "PRNG
246not seeded" error message may occur.
247
248The openssl command line utility will write back a new state to the
249default seeding file (and create this file if necessary) unless
250there was no sufficient seeding.
251
252Pointing $RANDFILE to an Entropy Gathering Daemon socket does not work.
253Use the "-rand" option of the OpenSSL command line tools instead.
254The $RANDFILE environment variable and $HOME/.rnd are only used by the
255OpenSSL command line tools. Applications using the OpenSSL library
256provide their own configuration options to specify the entropy source,
257please check out the documentation coming the with application.
258
259
260* Why do I get an "unable to write 'random state'" error message?
261
262
263Sometimes the openssl command line utility does not abort with
264a "PRNG not seeded" error message, but complains that it is
265"unable to write 'random state'". This message refers to the
266default seeding file (see previous answer). A possible reason
267is that no default filename is known because neither RANDFILE
268nor HOME is set. (Versions up to 0.9.6 used file ".rnd" in the
269current directory in this case, but this has changed with 0.9.6a.)
270
271
272* How do I create certificates or certificate requests?
273
274Check out the CA.pl(1) manual page. This provides a simple wrapper round
275the 'req', 'verify', 'ca' and 'pkcs12' utilities. For finer control check
276out the manual pages for the individual utilities and the certificate
277extensions documentation (currently in doc/openssl.txt).
278
279
280* Why can't I create certificate requests?
281
282You typically get the error:
283
284 unable to find 'distinguished_name' in config
285 problems making Certificate Request
286
287This is because it can't find the configuration file. Check out the
288DIAGNOSTICS section of req(1) for more information.
289
290
291* Why does <SSL program> fail with a certificate verify error?
292
293This problem is usually indicated by log messages saying something like
294"unable to get local issuer certificate" or "self signed certificate".
295When a certificate is verified its root CA must be "trusted" by OpenSSL
296this typically means that the CA certificate must be placed in a directory
297or file and the relevant program configured to read it. The OpenSSL program
298'verify' behaves in a similar way and issues similar error messages: check
299the verify(1) program manual page for more information.
300
301
302* Why can I only use weak ciphers when I connect to a server using OpenSSL?
303
304This is almost certainly because you are using an old "export grade" browser
305which only supports weak encryption. Upgrade your browser to support 128 bit
306ciphers.
307
308
309* How can I create DSA certificates?
310
311Check the CA.pl(1) manual page for a DSA certificate example.
312
313
314* Why can't I make an SSL connection to a server using a DSA certificate?
315
316Typically you'll see a message saying there are no shared ciphers when
317the same setup works fine with an RSA certificate. There are two possible
318causes. The client may not support connections to DSA servers most web
319browsers (including Netscape and MSIE) only support connections to servers
320supporting RSA cipher suites. The other cause is that a set of DH parameters
321has not been supplied to the server. DH parameters can be created with the
322dhparam(1) command and loaded using the SSL_CTX_set_tmp_dh() for example:
323check the source to s_server in apps/s_server.c for an example.
324
325
326* How can I remove the passphrase on a private key?
327
328Firstly you should be really *really* sure you want to do this. Leaving
329a private key unencrypted is a major security risk. If you decide that
330you do have to do this check the EXAMPLES sections of the rsa(1) and
331dsa(1) manual pages.
332
333
334* Why can't I use OpenSSL certificates with SSL client authentication?
335
336What will typically happen is that when a server requests authentication
337it will either not include your certificate or tell you that you have
338no client certificates (Netscape) or present you with an empty list box
339(MSIE). The reason for this is that when a server requests a client
340certificate it includes a list of CAs names which it will accept. Browsers
341will only let you select certificates from the list on the grounds that
342there is little point presenting a certificate which the server will
343reject.
344
345The solution is to add the relevant CA certificate to your servers "trusted
346CA list". How you do this depends on the server software in uses. You can
347print out the servers list of acceptable CAs using the OpenSSL s_client tool:
348
349openssl s_client -connect www.some.host:443 -prexit
350
351If your server only requests certificates on certain URLs then you may need
352to manually issue an HTTP GET command to get the list when s_client connects:
353
354GET /some/page/needing/a/certificate.html
355
356If your CA does not appear in the list then this confirms the problem.
357
358
359* Why does my browser give a warning about a mismatched hostname?
360
361Browsers expect the server's hostname to match the value in the commonName
362(CN) field of the certificate. If it does not then you get a warning.
363
364
365* How do I install a CA certificate into a browser?
366
367The usual way is to send the DER encoded certificate to the browser as
368MIME type application/x-x509-ca-cert, for example by clicking on an appropriate
369link. On MSIE certain extensions such as .der or .cacert may also work, or you
370can import the certificate using the certificate import wizard.
371
372You can convert a certificate to DER form using the command:
373
374openssl x509 -in ca.pem -outform DER -out ca.der
375
376Occasionally someone suggests using a command such as:
377
378openssl pkcs12 -export -out cacert.p12 -in cacert.pem -inkey cakey.pem
379
380DO NOT DO THIS! This command will give away your CAs private key and
381reduces its security to zero: allowing anyone to forge certificates in
382whatever name they choose.
383
384* Why is OpenSSL x509 DN output not conformant to RFC2253?
385
386The ways to print out the oneline format of the DN (Distinguished Name) have
387been extended in version 0.9.7 of OpenSSL. Using the new X509_NAME_print_ex()
388interface, the "-nameopt" option could be introduded. See the manual
389page of the "openssl x509" commandline tool for details. The old behaviour
390has however been left as default for the sake of compatibility.
391
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392* What is a "128 bit certificate"? Can I create one with OpenSSL?
393
394The term "128 bit certificate" is a highly misleading marketing term. It does
395*not* refer to the size of the public key in the certificate! A certificate
396containing a 128 bit RSA key would have negligible security.
397
398There were various other names such as "magic certificates", "SGC
399certificates", "step up certificates" etc.
400
401You can't generally create such a certificate using OpenSSL but there is no
402need to any more. Nowadays web browsers using unrestricted strong encryption
403are generally available.
404
405When there were tight export restrictions on the export of strong encryption
406software from the US only weak encryption algorithms could be freely exported
407(initially 40 bit and then 56 bit). It was widely recognised that this was
408inadequate. A relaxation the rules allowed the use of strong encryption but
409only to an authorised server.
410
411Two slighly different techniques were developed to support this, one used by
412Netscape was called "step up", the other used by MSIE was called "Server Gated
413Cryptography" (SGC). When a browser initially connected to a server it would
414check to see if the certificate contained certain extensions and was issued by
415an authorised authority. If these test succeeded it would reconnect using
416strong encryption.
417
418Only certain (initially one) certificate authorities could issue the
419certificates and they generally cost more than ordinary certificates.
420
421Although OpenSSL can create certificates containing the appropriate extensions
422the certificate would not come from a permitted authority and so would not
423be recognized.
424
425The export laws were later changed to allow almost unrestricted use of strong
426encryption so these certificates are now obsolete.
427
428
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429[BUILD] =======================================================================
430
431* Why does the linker complain about undefined symbols?
432
433Maybe the compilation was interrupted, and make doesn't notice that
434something is missing. Run "make clean; make".
435
436If you used ./Configure instead of ./config, make sure that you
437selected the right target. File formats may differ slightly between
438OS versions (for example sparcv8/sparcv9, or a.out/elf).
439
440In case you get errors about the following symbols, use the config
441option "no-asm", as described in INSTALL:
442
443 BF_cbc_encrypt, BF_decrypt, BF_encrypt, CAST_cbc_encrypt,
444 CAST_decrypt, CAST_encrypt, RC4, RC5_32_cbc_encrypt, RC5_32_decrypt,
445 RC5_32_encrypt, bn_add_words, bn_div_words, bn_mul_add_words,
446 bn_mul_comba4, bn_mul_comba8, bn_mul_words, bn_sqr_comba4,
447 bn_sqr_comba8, bn_sqr_words, bn_sub_words, des_decrypt3,
448 des_ede3_cbc_encrypt, des_encrypt, des_encrypt2, des_encrypt3,
449 des_ncbc_encrypt, md5_block_asm_host_order, sha1_block_asm_data_order
450
451If none of these helps, you may want to try using the current snapshot.
452If the problem persists, please submit a bug report.
453
454
455* Why does the OpenSSL test fail with "bc: command not found"?
456
457You didn't install "bc", the Unix calculator. If you want to run the
458tests, get GNU bc from ftp://ftp.gnu.org or from your OS distributor.
459
460
461* Why does the OpenSSL test fail with "bc: 1 no implemented"?
462
463On some SCO installations or versions, bc has a bug that gets triggered
464when you run the test suite (using "make test"). The message returned is
465"bc: 1 not implemented".
466
467The best way to deal with this is to find another implementation of bc
468and compile/install it. GNU bc (see http://www.gnu.org/software/software.html
469for download instructions) can be safely used, for example.
470
471
472* Why does the OpenSSL test fail with "bc: stack empty"?
473
474On some DG/ux versions, bc seems to have a too small stack for calculations
475that the OpenSSL bntest throws at it. This gets triggered when you run the
476test suite (using "make test"). The message returned is "bc: stack empty".
477
478The best way to deal with this is to find another implementation of bc
479and compile/install it. GNU bc (see http://www.gnu.org/software/software.html
480for download instructions) can be safely used, for example.
481
482
483* Why does the OpenSSL compilation fail on Alpha Tru64 Unix?
484
485On some Alpha installations running Tru64 Unix and Compaq C, the compilation
486of crypto/sha/sha_dgst.c fails with the message 'Fatal: Insufficient virtual
487memory to continue compilation.' As far as the tests have shown, this may be
488a compiler bug. What happens is that it eats up a lot of resident memory
489to build something, probably a table. The problem is clearly in the
490optimization code, because if one eliminates optimization completely (-O0),
491the compilation goes through (and the compiler consumes about 2MB of resident
492memory instead of 240MB or whatever one's limit is currently).
493
494There are three options to solve this problem:
495
4961. set your current data segment size soft limit higher. Experience shows
497that about 241000 kbytes seems to be enough on an AlphaServer DS10. You do
498this with the command 'ulimit -Sd nnnnnn', where 'nnnnnn' is the number of
499kbytes to set the limit to.
500
5012. If you have a hard limit that is lower than what you need and you can't
502get it changed, you can compile all of OpenSSL with -O0 as optimization
503level. This is however not a very nice thing to do for those who expect to
504get the best result from OpenSSL. A bit more complicated solution is the
505following:
506
507----- snip:start -----
508 make DIRS=crypto SDIRS=sha "`grep '^CFLAG=' Makefile.ssl | \
509 sed -e 's/ -O[0-9] / -O0 /'`"
510 rm `ls crypto/*.o crypto/sha/*.o | grep -v 'sha_dgst\.o'`
511 make
512----- snip:end -----
513
514This will only compile sha_dgst.c with -O0, the rest with the optimization
515level chosen by the configuration process. When the above is done, do the
516test and installation and you're set.
517
5183. Reconfigure the toolkit with no-sha0 option to leave out SHA0. It
519should not be used and is not used in SSL/TLS nor any other recognized
520protocol in either case.
521
522
523* Why does the OpenSSL compilation fail with "ar: command not found"?
524
525Getting this message is quite usual on Solaris 2, because Sun has hidden
526away 'ar' and other development commands in directories that aren't in
527$PATH by default. One of those directories is '/usr/ccs/bin'. The
528quickest way to fix this is to do the following (it assumes you use sh
529or any sh-compatible shell):
530
531----- snip:start -----
532 PATH=${PATH}:/usr/ccs/bin; export PATH
533----- snip:end -----
534
535and then redo the compilation. What you should really do is make sure
536'/usr/ccs/bin' is permanently in your $PATH, for example through your
537'.profile' (again, assuming you use a sh-compatible shell).
538
539
540* Why does the OpenSSL compilation fail on Win32 with VC++?
541
542Sometimes, you may get reports from VC++ command line (cl) that it
543can't find standard include files like stdio.h and other weirdnesses.
544One possible cause is that the environment isn't correctly set up.
545To solve that problem for VC++ versions up to 6, one should run
546VCVARS32.BAT which is found in the 'bin' subdirectory of the VC++
547installation directory (somewhere under 'Program Files'). For VC++
548version 7 (and up?), which is also called VS.NET, the file is called
549VSVARS32.BAT instead.
550This needs to be done prior to running NMAKE, and the changes are only
551valid for the current DOS session.
552
553
554* What is special about OpenSSL on Redhat?
555
556Red Hat Linux (release 7.0 and later) include a preinstalled limited
557version of OpenSSL. For patent reasons, support for IDEA, RC5 and MDC2
558is disabled in this version. The same may apply to other Linux distributions.
559Users may therefore wish to install more or all of the features left out.
560
561To do this you MUST ensure that you do not overwrite the openssl that is in
562/usr/bin on your Red Hat machine. Several packages depend on this file,
563including sendmail and ssh. /usr/local/bin is a good alternative choice. The
564libraries that come with Red Hat 7.0 onwards have different names and so are
565not affected. (eg For Red Hat 7.2 they are /lib/libssl.so.0.9.6b and
566/lib/libcrypto.so.0.9.6b with symlinks /lib/libssl.so.2 and
567/lib/libcrypto.so.2 respectively).
568
569Please note that we have been advised by Red Hat attempting to recompile the
570openssl rpm with all the cryptography enabled will not work. All other
571packages depend on the original Red Hat supplied openssl package. It is also
572worth noting that due to the way Red Hat supplies its packages, updates to
573openssl on each distribution never change the package version, only the
574build number. For example, on Red Hat 7.1, the latest openssl package has
575version number 0.9.6 and build number 9 even though it contains all the
576relevant updates in packages up to and including 0.9.6b.
577
578A possible way around this is to persuade Red Hat to produce a non-US
579version of Red Hat Linux.
580
581FYI: Patent numbers and expiry dates of US patents:
582MDC-2: 4,908,861 13/03/2007
583IDEA: 5,214,703 25/05/2010
584RC5: 5,724,428 03/03/2015
585
586
587* Why does the OpenSSL compilation fail on MacOS X?
588
589If the failure happens when trying to build the "openssl" binary, with
590a large number of undefined symbols, it's very probable that you have
591OpenSSL 0.9.6b delivered with the operating system (you can find out by
592running '/usr/bin/openssl version') and that you were trying to build
593OpenSSL 0.9.7 or newer. The problem is that the loader ('ld') in
594MacOS X has a misfeature that's quite difficult to go around.
595Look in the file PROBLEMS for a more detailed explanation and for possible
596solutions.
597
598
599* Why does the OpenSSL test suite fail on MacOS X?
600
601If the failure happens when running 'make test' and the RC4 test fails,
602it's very probable that you have OpenSSL 0.9.6b delivered with the
603operating system (you can find out by running '/usr/bin/openssl version')
604and that you were trying to build OpenSSL 0.9.6d. The problem is that
605the loader ('ld') in MacOS X has a misfeature that's quite difficult to
606go around and has linked the programs "openssl" and the test programs
607with /usr/lib/libcrypto.dylib and /usr/lib/libssl.dylib instead of the
608libraries you just built.
609Look in the file PROBLEMS for a more detailed explanation and for possible
610solutions.
611
612* Why does the OpenSSL test suite fail in BN_sqr test [on a 64-bit platform]?
613
614Failure in BN_sqr test is most likely caused by a failure to configure the
615toolkit for current platform or lack of support for the platform in question.
616Run './config -t' and './apps/openssl version -p'. Do these platform
617identifiers match? If they don't, then you most likely failed to run
618./config and you're hereby advised to do so before filing a bug report.
619If ./config itself fails to run, then it's most likely problem with your
620local environment and you should turn to your system administrator (or
621similar). If identifiers match (and/or no alternative identifier is
622suggested by ./config script), then the platform is unsupported. There might
623or might not be a workaround. Most notably on SPARC64 platforms with GNU
624C compiler you should be able to produce a working build by running
625'./config -m32'. I understand that -m32 might not be what you want/need,
626but the build should be operational. For further details turn to
627<openssl-dev@openssl.org>.
628
629* Why does OpenBSD-i386 build fail on des-586.s with "Unimplemented segment type"?
630
631As of 0.9.7 assembler routines were overhauled for position independence
632of the machine code, which is essential for shared library support. For
633some reason OpenBSD is equipped with an out-of-date GNU assembler which
634finds the new code offensive. To work around the problem, configure with
635no-asm (and sacrifice a great deal of performance) or patch your assembler
636according to <URL: http://www.openssl.org/~appro/gas-1.92.3.OpenBSD.patch>.
637For your convenience a pre-compiled replacement binary is provided at
638<URL: http://www.openssl.org/~appro/gas-1.92.3.static.aout.bin>.
639Reportedly elder *BSD a.out platforms also suffer from this problem and
640remedy should be same. Provided binary is statically linked and should be
641working across wider range of *BSD branches, not just OpenBSD.
642
643* Why does the OpenSSL test suite fail in sha512t on x86 CPU?
644
645If the test program in question fails withs SIGILL, Illegal Instruction
646exception, then you more than likely to run SSE2-capable CPU, such as
647Intel P4, under control of kernel which does not support SSE2
648instruction extentions. See accompanying INSTALL file and
649OPENSSL_ia32cap(3) documentation page for further information.
650
651* Why does compiler fail to compile sha512.c?
652
653OpenSSL SHA-512 implementation depends on compiler support for 64-bit
654integer type. Few elder compilers [ULTRIX cc, SCO compiler to mention a
655couple] lack support for this and therefore are incapable of compiling
656the module in question. The recommendation is to disable SHA-512 by
657adding no-sha512 to ./config [or ./Configure] command line. Another
658possible alternative might be to switch to GCC.
659
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660* Test suite still fails, what to do?
661
662Another common reason for failure to complete some particular test is
663simply bad code generated by a buggy component in toolchain or deficiency
664in run-time environment. There are few cases documented in PROBLEMS file,
665consult it for possible workaround before you beat the drum. Even if you
666don't find solution or even mention there, do reserve for possibility of
667a compiler bug. Compiler bugs might appear in rather bizarre ways, they
668never make sense, and tend to emerge when you least expect them. In order
669to identify one, drop optimization level, e.g. by editing CFLAG line in
670top-level Makefile, recompile and re-run the test.
671
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672[PROG] ========================================================================
673
674* Is OpenSSL thread-safe?
675
676Yes (with limitations: an SSL connection may not concurrently be used
677by multiple threads). On Windows and many Unix systems, OpenSSL
678automatically uses the multi-threaded versions of the standard
679libraries. If your platform is not one of these, consult the INSTALL
680file.
681
682Multi-threaded applications must provide two callback functions to
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683OpenSSL by calling CRYPTO_set_locking_callback() and
684CRYPTO_set_id_callback(). This is described in the threads(3)
685manpage.
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686
687* I've compiled a program under Windows and it crashes: why?
688
689This is usually because you've missed the comment in INSTALL.W32.
690Your application must link against the same version of the Win32
691C-Runtime against which your openssl libraries were linked. The
692default version for OpenSSL is /MD - "Multithreaded DLL".
693
694If you are using Microsoft Visual C++'s IDE (Visual Studio), in
695many cases, your new project most likely defaulted to "Debug
696Singlethreaded" - /ML. This is NOT interchangeable with /MD and your
697program will crash, typically on the first BIO related read or write
698operation.
699
700For each of the six possible link stage configurations within Win32,
701your application must link against the same by which OpenSSL was
702built. If you are using MS Visual C++ (Studio) this can be changed
703by:
704
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705 1. Select Settings... from the Project Menu.
706 2. Select the C/C++ Tab.
707 3. Select "Code Generation from the "Category" drop down list box
708 4. Select the Appropriate library (see table below) from the "Use
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709 run-time library" drop down list box. Perform this step for both
710 your debug and release versions of your application (look at the
711 top left of the settings panel to change between the two)
712
713 Single Threaded /ML - MS VC++ often defaults to
714 this for the release
715 version of a new project.
716 Debug Single Threaded /MLd - MS VC++ often defaults to
717 this for the debug version
718 of a new project.
719 Multithreaded /MT
720 Debug Multithreaded /MTd
721 Multithreaded DLL /MD - OpenSSL defaults to this.
722 Debug Multithreaded DLL /MDd
723
724Note that debug and release libraries are NOT interchangeable. If you
725built OpenSSL with /MD your application must use /MD and cannot use /MDd.
726
727As per 0.9.8 the above limitation is eliminated for .DLLs. OpenSSL
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729default /MD] can be deployed with application compiled with different
730option or even different compiler. But there is a catch! Instead of
731re-compiling OpenSSL toolkit, as you would have to with prior versions,
732you have to compile small C snippet with compiler and/or options of
733your choice. The snippet gets installed as
734<install-root>/include/openssl/applink.c and should be either added to
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735your application project or simply #include-d in one [and only one]
736of your application source files. Failure to link this shim module
737into your application manifests itself as fatal "no OPENSSL_Applink"
738run-time error. An explicit reminder is due that in this situation
739[mixing compiler options] it is as important to add CRYPTO_malloc_init
740prior first call to OpenSSL.
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741
742* How do I read or write a DER encoded buffer using the ASN1 functions?
743
744You have two options. You can either use a memory BIO in conjunction
745with the i2d_*_bio() or d2i_*_bio() functions or you can use the
746i2d_*(), d2i_*() functions directly. Since these are often the
747cause of grief here are some code fragments using PKCS7 as an example:
748
749 unsigned char *buf, *p;
750 int len;
751
752 len = i2d_PKCS7(p7, NULL);
753 buf = OPENSSL_malloc(len); /* or Malloc, error checking omitted */
754 p = buf;
755 i2d_PKCS7(p7, &p);
756
757At this point buf contains the len bytes of the DER encoding of
758p7.
759
760The opposite assumes we already have len bytes in buf:
761
762 unsigned char *p;
763 p = buf;
764 p7 = d2i_PKCS7(NULL, &p, len);
765
766At this point p7 contains a valid PKCS7 structure of NULL if an error
767occurred. If an error occurred ERR_print_errors(bio) should give more
768information.
769
770The reason for the temporary variable 'p' is that the ASN1 functions
771increment the passed pointer so it is ready to read or write the next
772structure. This is often a cause of problems: without the temporary
773variable the buffer pointer is changed to point just after the data
774that has been read or written. This may well be uninitialized data
775and attempts to free the buffer will have unpredictable results
776because it no longer points to the same address.
777
778
779* OpenSSL uses DER but I need BER format: does OpenSSL support BER?
780
781The short answer is yes, because DER is a special case of BER and OpenSSL
782ASN1 decoders can process BER.
783
784The longer answer is that ASN1 structures can be encoded in a number of
785different ways. One set of ways is the Basic Encoding Rules (BER) with various
786permissible encodings. A restriction of BER is the Distinguished Encoding
787Rules (DER): these uniquely specify how a given structure is encoded.
788
789Therefore, because DER is a special case of BER, DER is an acceptable encoding
790for BER.
791
792
793* I've tried using <M_some_evil_pkcs12_macro> and I get errors why?
794
795This usually happens when you try compiling something using the PKCS#12
796macros with a C++ compiler. There is hardly ever any need to use the
797PKCS#12 macros in a program, it is much easier to parse and create
798PKCS#12 files using the PKCS12_parse() and PKCS12_create() functions
799documented in doc/openssl.txt and with examples in demos/pkcs12. The
800'pkcs12' application has to use the macros because it prints out
801debugging information.
802
803
804* I've called <some function> and it fails, why?
805
806Before submitting a report or asking in one of the mailing lists, you
807should try to determine the cause. In particular, you should call
808ERR_print_errors() or ERR_print_errors_fp() after the failed call
809and see if the message helps. Note that the problem may occur earlier
810than you think -- you should check for errors after every call where
811it is possible, otherwise the actual problem may be hidden because
812some OpenSSL functions clear the error state.
813
814
815* I just get a load of numbers for the error output, what do they mean?
816
817The actual format is described in the ERR_print_errors() manual page.
818You should call the function ERR_load_crypto_strings() before hand and
819the message will be output in text form. If you can't do this (for example
820it is a pre-compiled binary) you can use the errstr utility on the error
821code itself (the hex digits after the second colon).
822
823
824* Why do I get errors about unknown algorithms?
825
826This can happen under several circumstances such as reading in an
827encrypted private key or attempting to decrypt a PKCS#12 file. The cause
828is forgetting to load OpenSSL's table of algorithms with
829OpenSSL_add_all_algorithms(). See the manual page for more information.
830
831
832* Why can't the OpenSSH configure script detect OpenSSL?
833
834Several reasons for problems with the automatic detection exist.
835OpenSSH requires at least version 0.9.5a of the OpenSSL libraries.
836Sometimes the distribution has installed an older version in the system
837locations that is detected instead of a new one installed. The OpenSSL
838library might have been compiled for another CPU or another mode (32/64 bits).
839Permissions might be wrong.
840
841The general answer is to check the config.log file generated when running
842the OpenSSH configure script. It should contain the detailed information
843on why the OpenSSL library was not detected or considered incompatible.
844
845
846* Can I use OpenSSL's SSL library with non-blocking I/O?
847
848Yes; make sure to read the SSL_get_error(3) manual page!
849
850A pitfall to avoid: Don't assume that SSL_read() will just read from
851the underlying transport or that SSL_write() will just write to it --
852it is also possible that SSL_write() cannot do any useful work until
853there is data to read, or that SSL_read() cannot do anything until it
854is possible to send data. One reason for this is that the peer may
855request a new TLS/SSL handshake at any time during the protocol,
856requiring a bi-directional message exchange; both SSL_read() and
857SSL_write() will try to continue any pending handshake.
858
859
860* Why doesn't my server application receive a client certificate?
861
862Due to the TLS protocol definition, a client will only send a certificate,
863if explicitly asked by the server. Use the SSL_VERIFY_PEER flag of the
864SSL_CTX_set_verify() function to enable the use of client certificates.
865
866
867* Why does compilation fail due to an undefined symbol NID_uniqueIdentifier?
868
869For OpenSSL 0.9.7 the OID table was extended and corrected. In earlier
870versions, uniqueIdentifier was incorrectly used for X.509 certificates.
871The correct name according to RFC2256 (LDAP) is x500UniqueIdentifier.
872Change your code to use the new name when compiling against OpenSSL 0.9.7.
873
874
875* I think I've detected a memory leak, is this a bug?
876
877In most cases the cause of an apparent memory leak is an OpenSSL internal table
878that is allocated when an application starts up. Since such tables do not grow
879in size over time they are harmless.
880
881These internal tables can be freed up when an application closes using various
882functions. Currently these include following:
883
884Thread-local cleanup functions:
885
886 ERR_remove_state()
887
888Application-global cleanup functions that are aware of usage (and therefore
889thread-safe):
890
891 ENGINE_cleanup() and CONF_modules_unload()
892
893"Brutal" (thread-unsafe) Application-global cleanup functions:
894
895 ERR_free_strings(), EVP_cleanup() and CRYPTO_cleanup_all_ex_data().
896
897
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898* Why does Valgrind complain about the use of uninitialized data?
899
900When OpenSSL's PRNG routines are called to generate random numbers the supplied
901buffer contents are mixed into the entropy pool: so it technically does not
902matter whether the buffer is initialized at this point or not. Valgrind (and
903other test tools) will complain about this. When using Valgrind, make sure the
904OpenSSL library has been compiled with the PURIFY macro defined (-DPURIFY)
905to get rid of these warnings.
906
907
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908===============================================================================
909