* Where can I get a compiled version of OpenSSL?
* Why aren't tools like 'autoconf' and 'libtool' used?
* What is an 'engine' version?
+* How do I check the authenticity of the OpenSSL distribution?
+* How does the versioning scheme work?
[LEGAL] Legal questions
* How can I remove the passphrase on a private key?
* Why can't I use OpenSSL certificates with SSL client authentication?
* Why does my browser give a warning about a mismatched hostname?
+* How do I install a CA certificate into a browser?
+* Why is OpenSSL x509 DN output not conformant to RFC2253?
+* What is a "128 bit certificate"? Can I create one with OpenSSL?
+* Why does OpenSSL set the authority key identifier extension incorrectly?
+* How can I set up a bundle of commercial root CA certificates?
+* Some secure servers 'hang' with OpenSSL 1.0.1, is this a bug?
[BUILD] Questions about building and testing OpenSSL
* Why does the linker complain about undefined symbols?
* Why does the OpenSSL test fail with "bc: command not found"?
* Why does the OpenSSL test fail with "bc: 1 no implemented"?
+* Why does the OpenSSL test fail with "bc: stack empty"?
* Why does the OpenSSL compilation fail on Alpha Tru64 Unix?
* Why does the OpenSSL compilation fail with "ar: command not found"?
* Why does the OpenSSL compilation fail on Win32 with VC++?
+* What is special about OpenSSL on Redhat?
+* Why does the OpenSSL compilation fail on MacOS X?
+* Why does the OpenSSL test suite fail on MacOS X?
+* Why does the OpenSSL test suite fail in BN_sqr test [on a 64-bit platform]?
+* Why does OpenBSD-i386 build fail on des-586.s with "Unimplemented segment type"?
+* Why does the OpenSSL test suite fail in sha512t on x86 CPU?
+* Why does compiler fail to compile sha512.c?
+* Test suite still fails, what to do?
+* I think I've found a bug, what should I do?
+* I'm SURE I've found a bug, how do I report it?
+* I've found a security issue, how do I report it?
[PROG] Questions about programming with OpenSSL
* Is OpenSSL thread-safe?
* I've compiled a program under Windows and it crashes: why?
* How do I read or write a DER encoded buffer using the ASN1 functions?
+* OpenSSL uses DER but I need BER format: does OpenSSL support BER?
* I've tried using <M_some_evil_pkcs12_macro> and I get errors why?
* I've called <some function> and it fails, why?
* I just get a load of numbers for the error output, what do they mean?
* Why can't the OpenSSH configure script detect OpenSSL?
* Can I use OpenSSL's SSL library with non-blocking I/O?
* Why doesn't my server application receive a client certificate?
+* Why does compilation fail due to an undefined symbol NID_uniqueIdentifier?
+* I think I've detected a memory leak, is this a bug?
+* Why does Valgrind complain about the use of uninitialized data?
+* Why doesn't a memory BIO work when a file does?
+* Where are the declarations and implementations of d2i_X509() etc?
===============================================================================
* Which is the current version of OpenSSL?
The current version is available from <URL: http://www.openssl.org>.
-OpenSSL 0.9.6b was released on July 9th, 2001.
+OpenSSL 1.0.1e was released on Feb 11, 2013.
In addition to the current stable release, you can also access daily
snapshots of the OpenSSL development version at <URL:
-ftp://ftp.openssl.org/snapshot/>, or get it by anonymous CVS access.
+ftp://ftp.openssl.org/snapshot/>, or get it by anonymous Git access.
* Where is the documentation?
OpenSSL includes a command line utility that can be used to perform a
variety of cryptographic functions. It is described in the openssl(1)
-manpage. Documentation for developers is currently being written. A
-few manual pages already are available; overviews over libcrypto and
+manpage. Documentation for developers is currently being written. Many
+manual pages are available; overviews over libcrypto and
libssl are given in the crypto(3) and ssl(3) manpages.
The OpenSSL manpages are installed in /usr/local/ssl/man/ (or a
different directory if you specified one as described in INSTALL).
In addition, you can read the most current versions at
-<URL: http://www.openssl.org/docs/>.
+<URL: http://www.openssl.org/docs/>. Note that the online documents refer
+to the very latest development versions of OpenSSL and may include features
+not present in released versions. If in doubt refer to the documentation
+that came with the version of OpenSSL you are using. The pod format
+documentation is included in each OpenSSL distribution under the docs
+directory.
For information on parts of libcrypto that are not yet documented, you
might want to read Ariel Glenn's documentation on SSLeay 0.9, OpenSSL's
* Where can I get a compiled version of OpenSSL?
+You can finder pointers to binary distributions in
+<URL: http://www.openssl.org/related/binaries.html> .
+
Some applications that use OpenSSL are distributed in binary form.
When using such an application, you don't need to install OpenSSL
yourself; the application will include the required parts (e.g. DLLs).
-If you want to install OpenSSL on a Windows system and you don't have
+If you want to build OpenSSL on a Windows system and you don't have
a C compiler, read the "Mingw32" section of INSTALL.W32 for information
on how to obtain and install the free GNU C compiler.
With version 0.9.6 OpenSSL was extended to interface to external crypto
hardware. This was realized in a special release '0.9.6-engine'. With
-version 0.9.7 (not yet released) the changes were merged into the main
-development line, so that the special release is no longer necessary.
+version 0.9.7 the changes were merged into the main development line,
+so that the special release is no longer necessary.
+
+* How do I check the authenticity of the OpenSSL distribution?
+
+We provide MD5 digests and ASC signatures of each tarball.
+Use MD5 to check that a tarball from a mirror site is identical:
+
+ md5sum TARBALL | awk '{print $1;}' | cmp - TARBALL.md5
+
+You can check authenticity using pgp or gpg. You need the OpenSSL team
+member public key used to sign it (download it from a key server, see a
+list of keys at <URL: http://www.openssl.org/about/>). Then
+just do:
+
+ pgp TARBALL.asc
+
+* How does the versioning scheme work?
+
+After the release of OpenSSL 1.0.0 the versioning scheme changed. Letter
+releases (e.g. 1.0.1a) can only contain bug and security fixes and no
+new features. Minor releases change the last number (e.g. 1.0.2) and
+can contain new features that retain binary compatibility. Changes to
+the middle number are considered major releases and neither source nor
+binary compatibility is guaranteed.
+
+Therefore the answer to the common question "when will feature X be
+backported to OpenSSL 1.0.0/0.9.8?" is "never" but it could appear
+in the next minor release.
+
+* What happens when the letter release reaches z?
+
+It was decided after the release of OpenSSL 0.9.8y the next version should
+be 0.9.8za then 0.9.8zb and so on.
+
[LEGAL] =======================================================================
property rights, please consult a lawyer. The OpenSSL team does not
offer legal advice.
-You can configure OpenSSL so as not to use RC5 and IDEA by using
- ./config no-rc5 no-idea
+You can configure OpenSSL so as not to use IDEA, MDC2 and RC5 by using
+ ./config no-idea no-mdc2 no-rc5
* Can I use OpenSSL with GPL software?
their software on operating systems that don't normally include OpenSSL.
If you develop open source software that uses OpenSSL, you may find it
-useful to choose an other license than the GPL, or state explicitely that
+useful to choose an other license than the GPL, or state explicitly that
"This program is released under the GPL with the additional exemption that
compiling, linking, and/or using OpenSSL is allowed." If you are using
GPL software developed by others, you may want to ask the copyright holder
Cryptographic software needs a source of unpredictable data to work
correctly. Many open source operating systems provide a "randomness
-device" that serves this purpose. On other systems, applications have
-to call the RAND_add() or RAND_seed() function with appropriate data
-before generating keys or performing public key encryption.
-(These functions initialize the pseudo-random number generator, PRNG.)
-
-Some broken applications do not do this. As of version 0.9.5, the
-OpenSSL functions that need randomness report an error if the random
-number generator has not been seeded with at least 128 bits of
-randomness. If this error occurs, please contact the author of the
-application you are using. It is likely that it never worked
-correctly. OpenSSL 0.9.5 and later make the error visible by refusing
-to perform potentially insecure encryption.
+device" (/dev/urandom or /dev/random) that serves this purpose.
+All OpenSSL versions try to use /dev/urandom by default; starting with
+version 0.9.7, OpenSSL also tries /dev/random if /dev/urandom is not
+available.
+
+On other systems, applications have to call the RAND_add() or
+RAND_seed() function with appropriate data before generating keys or
+performing public key encryption. (These functions initialize the
+pseudo-random number generator, PRNG.) Some broken applications do
+not do this. As of version 0.9.5, the OpenSSL functions that need
+randomness report an error if the random number generator has not been
+seeded with at least 128 bits of randomness. If this error occurs and
+is not discussed in the documentation of the application you are
+using, please contact the author of that application; it is likely
+that it never worked correctly. OpenSSL 0.9.5 and later make the
+error visible by refusing to perform potentially insecure encryption.
+
+If you are using Solaris 8, you can add /dev/urandom and /dev/random
+devices by installing patch 112438 (Sparc) or 112439 (x86), which are
+available via the Patchfinder at <URL: http://sunsolve.sun.com>
+(Solaris 9 includes these devices by default). For /dev/random support
+for earlier Solaris versions, see Sun's statement at
+<URL: http://sunsolve.sun.com/pub-cgi/retrieve.pl?doc=fsrdb/27606&zone_32=SUNWski>
+(the SUNWski package is available in patch 105710).
On systems without /dev/urandom and /dev/random, it is a good idea to
use the Entropy Gathering Demon (EGD); see the RAND_egd() manpage for
provide their own configuration options to specify the entropy source,
please check out the documentation coming the with application.
-For Solaris 2.6, Tim Nibbe <tnibbe@sprint.net> and others have suggested
-installing the SUNski package from Sun patch 105710-01 (Sparc) which
-adds a /dev/random device and make sure it gets used, usually through
-$RANDFILE. There are probably similar patches for the other Solaris
-versions. However, be warned that /dev/random is usually a blocking
-device, which may have some effects on OpenSSL.
-
* Why do I get an "unable to write 'random state'" error message?
Check out the CA.pl(1) manual page. This provides a simple wrapper round
the 'req', 'verify', 'ca' and 'pkcs12' utilities. For finer control check
out the manual pages for the individual utilities and the certificate
-extensions documentation (currently in doc/openssl.txt).
+extensions documentation (in ca(1), req(1), x509v3_config(5) )
* Why can't I create certificate requests?
reject.
The solution is to add the relevant CA certificate to your servers "trusted
-CA list". How you do this depends on the server sofware in uses. You can
+CA list". How you do this depends on the server software in uses. You can
print out the servers list of acceptable CAs using the OpenSSL s_client tool:
openssl s_client -connect www.some.host:443 -prexit
(CN) field of the certificate. If it does not then you get a warning.
+* How do I install a CA certificate into a browser?
+
+The usual way is to send the DER encoded certificate to the browser as
+MIME type application/x-x509-ca-cert, for example by clicking on an appropriate
+link. On MSIE certain extensions such as .der or .cacert may also work, or you
+can import the certificate using the certificate import wizard.
+
+You can convert a certificate to DER form using the command:
+
+openssl x509 -in ca.pem -outform DER -out ca.der
+
+Occasionally someone suggests using a command such as:
+
+openssl pkcs12 -export -out cacert.p12 -in cacert.pem -inkey cakey.pem
+
+DO NOT DO THIS! This command will give away your CAs private key and
+reduces its security to zero: allowing anyone to forge certificates in
+whatever name they choose.
+
+* Why is OpenSSL x509 DN output not conformant to RFC2253?
+
+The ways to print out the oneline format of the DN (Distinguished Name) have
+been extended in version 0.9.7 of OpenSSL. Using the new X509_NAME_print_ex()
+interface, the "-nameopt" option could be introduded. See the manual
+page of the "openssl x509" commandline tool for details. The old behaviour
+has however been left as default for the sake of compatibility.
+
+* What is a "128 bit certificate"? Can I create one with OpenSSL?
+
+The term "128 bit certificate" is a highly misleading marketing term. It does
+*not* refer to the size of the public key in the certificate! A certificate
+containing a 128 bit RSA key would have negligible security.
+
+There were various other names such as "magic certificates", "SGC
+certificates", "step up certificates" etc.
+
+You can't generally create such a certificate using OpenSSL but there is no
+need to any more. Nowadays web browsers using unrestricted strong encryption
+are generally available.
+
+When there were tight restrictions on the export of strong encryption
+software from the US only weak encryption algorithms could be freely exported
+(initially 40 bit and then 56 bit). It was widely recognised that this was
+inadequate. A relaxation of the rules allowed the use of strong encryption but
+only to an authorised server.
+
+Two slighly different techniques were developed to support this, one used by
+Netscape was called "step up", the other used by MSIE was called "Server Gated
+Cryptography" (SGC). When a browser initially connected to a server it would
+check to see if the certificate contained certain extensions and was issued by
+an authorised authority. If these test succeeded it would reconnect using
+strong encryption.
+
+Only certain (initially one) certificate authorities could issue the
+certificates and they generally cost more than ordinary certificates.
+
+Although OpenSSL can create certificates containing the appropriate extensions
+the certificate would not come from a permitted authority and so would not
+be recognized.
+
+The export laws were later changed to allow almost unrestricted use of strong
+encryption so these certificates are now obsolete.
+
+
+* Why does OpenSSL set the authority key identifier (AKID) extension incorrectly?
+
+It doesn't: this extension is often the cause of confusion.
+
+Consider a certificate chain A->B->C so that A signs B and B signs C. Suppose
+certificate C contains AKID.
+
+The purpose of this extension is to identify the authority certificate B. This
+can be done either by including the subject key identifier of B or its issuer
+name and serial number.
+
+In this latter case because it is identifying certifcate B it must contain the
+issuer name and serial number of B.
+
+It is often wrongly assumed that it should contain the subject name of B. If it
+did this would be redundant information because it would duplicate the issuer
+name of C.
+
+
+* How can I set up a bundle of commercial root CA certificates?
+
+The OpenSSL software is shipped without any root CA certificate as the
+OpenSSL project does not have any policy on including or excluding
+any specific CA and does not intend to set up such a policy. Deciding
+about which CAs to support is up to application developers or
+administrators.
+
+Other projects do have other policies so you can for example extract the CA
+bundle used by Mozilla and/or modssl as described in this article:
+
+ <URL: http://www.mail-archive.com/modssl-users@modssl.org/msg16980.html>
+
+
+* Some secure servers 'hang' with OpenSSL 1.0.1, is this a bug?
+
+OpenSSL 1.0.1 is the first release to support TLS 1.2, among other things,
+this increases the size of the default ClientHello message to more than
+255 bytes in length. Some software cannot handle this and hangs. For more
+details and workarounds see:
+
+ <URL: http://rt.openssl.org/Ticket/Display.html?user=guest&pass=guest&id=2771>
+
+
[BUILD] =======================================================================
* Why does the linker complain about undefined symbols?
"bc: 1 not implemented".
The best way to deal with this is to find another implementation of bc
-and compile/install it. GNU bc (see http://www.gnu.org/software/software.html
+and compile/install it. GNU bc (see <URL: http://www.gnu.org/software/software.html>
+for download instructions) can be safely used, for example.
+
+
+* Why does the OpenSSL test fail with "bc: stack empty"?
+
+On some DG/ux versions, bc seems to have a too small stack for calculations
+that the OpenSSL bntest throws at it. This gets triggered when you run the
+test suite (using "make test"). The message returned is "bc: stack empty".
+
+The best way to deal with this is to find another implementation of bc
+and compile/install it. GNU bc (see <URL: http://www.gnu.org/software/software.html>
for download instructions) can be safely used, for example.
level chosen by the configuration process. When the above is done, do the
test and installation and you're set.
+3. Reconfigure the toolkit with no-sha0 option to leave out SHA0. It
+should not be used and is not used in SSL/TLS nor any other recognized
+protocol in either case.
+
* Why does the OpenSSL compilation fail with "ar: command not found"?
Sometimes, you may get reports from VC++ command line (cl) that it
can't find standard include files like stdio.h and other weirdnesses.
One possible cause is that the environment isn't correctly set up.
-To solve that problem, one should run VCVARS32.BAT which is found in
-the 'bin' subdirectory of the VC++ installation directory (somewhere
-under 'Program Files'). This needs to be done prior to running NMAKE,
-and the changes are only valid for the current DOS session.
-
+To solve that problem for VC++ versions up to 6, one should run
+VCVARS32.BAT which is found in the 'bin' subdirectory of the VC++
+installation directory (somewhere under 'Program Files'). For VC++
+version 7 (and up?), which is also called VS.NET, the file is called
+VSVARS32.BAT instead.
+This needs to be done prior to running NMAKE, and the changes are only
+valid for the current DOS session.
+
+
+* What is special about OpenSSL on Redhat?
+
+Red Hat Linux (release 7.0 and later) include a preinstalled limited
+version of OpenSSL. For patent reasons, support for IDEA, RC5 and MDC2
+is disabled in this version. The same may apply to other Linux distributions.
+Users may therefore wish to install more or all of the features left out.
+
+To do this you MUST ensure that you do not overwrite the openssl that is in
+/usr/bin on your Red Hat machine. Several packages depend on this file,
+including sendmail and ssh. /usr/local/bin is a good alternative choice. The
+libraries that come with Red Hat 7.0 onwards have different names and so are
+not affected. (eg For Red Hat 7.2 they are /lib/libssl.so.0.9.6b and
+/lib/libcrypto.so.0.9.6b with symlinks /lib/libssl.so.2 and
+/lib/libcrypto.so.2 respectively).
+
+Please note that we have been advised by Red Hat attempting to recompile the
+openssl rpm with all the cryptography enabled will not work. All other
+packages depend on the original Red Hat supplied openssl package. It is also
+worth noting that due to the way Red Hat supplies its packages, updates to
+openssl on each distribution never change the package version, only the
+build number. For example, on Red Hat 7.1, the latest openssl package has
+version number 0.9.6 and build number 9 even though it contains all the
+relevant updates in packages up to and including 0.9.6b.
+
+A possible way around this is to persuade Red Hat to produce a non-US
+version of Red Hat Linux.
+
+FYI: Patent numbers and expiry dates of US patents:
+MDC-2: 4,908,861 13/03/2007
+IDEA: 5,214,703 25/05/2010
+RC5: 5,724,428 03/03/2015
+
+
+* Why does the OpenSSL compilation fail on MacOS X?
+
+If the failure happens when trying to build the "openssl" binary, with
+a large number of undefined symbols, it's very probable that you have
+OpenSSL 0.9.6b delivered with the operating system (you can find out by
+running '/usr/bin/openssl version') and that you were trying to build
+OpenSSL 0.9.7 or newer. The problem is that the loader ('ld') in
+MacOS X has a misfeature that's quite difficult to go around.
+Look in the file PROBLEMS for a more detailed explanation and for possible
+solutions.
+
+
+* Why does the OpenSSL test suite fail on MacOS X?
+
+If the failure happens when running 'make test' and the RC4 test fails,
+it's very probable that you have OpenSSL 0.9.6b delivered with the
+operating system (you can find out by running '/usr/bin/openssl version')
+and that you were trying to build OpenSSL 0.9.6d. The problem is that
+the loader ('ld') in MacOS X has a misfeature that's quite difficult to
+go around and has linked the programs "openssl" and the test programs
+with /usr/lib/libcrypto.dylib and /usr/lib/libssl.dylib instead of the
+libraries you just built.
+Look in the file PROBLEMS for a more detailed explanation and for possible
+solutions.
+
+* Why does the OpenSSL test suite fail in BN_sqr test [on a 64-bit platform]?
+
+Failure in BN_sqr test is most likely caused by a failure to configure the
+toolkit for current platform or lack of support for the platform in question.
+Run './config -t' and './apps/openssl version -p'. Do these platform
+identifiers match? If they don't, then you most likely failed to run
+./config and you're hereby advised to do so before filing a bug report.
+If ./config itself fails to run, then it's most likely problem with your
+local environment and you should turn to your system administrator (or
+similar). If identifiers match (and/or no alternative identifier is
+suggested by ./config script), then the platform is unsupported. There might
+or might not be a workaround. Most notably on SPARC64 platforms with GNU
+C compiler you should be able to produce a working build by running
+'./config -m32'. I understand that -m32 might not be what you want/need,
+but the build should be operational. For further details turn to
+<openssl-dev@openssl.org>.
+
+* Why does OpenBSD-i386 build fail on des-586.s with "Unimplemented segment type"?
+
+As of 0.9.7 assembler routines were overhauled for position independence
+of the machine code, which is essential for shared library support. For
+some reason OpenBSD is equipped with an out-of-date GNU assembler which
+finds the new code offensive. To work around the problem, configure with
+no-asm (and sacrifice a great deal of performance) or patch your assembler
+according to <URL: http://www.openssl.org/~appro/gas-1.92.3.OpenBSD.patch>.
+For your convenience a pre-compiled replacement binary is provided at
+<URL: http://www.openssl.org/~appro/gas-1.92.3.static.aout.bin>.
+Reportedly elder *BSD a.out platforms also suffer from this problem and
+remedy should be same. Provided binary is statically linked and should be
+working across wider range of *BSD branches, not just OpenBSD.
+
+* Why does the OpenSSL test suite fail in sha512t on x86 CPU?
+
+If the test program in question fails withs SIGILL, Illegal Instruction
+exception, then you more than likely to run SSE2-capable CPU, such as
+Intel P4, under control of kernel which does not support SSE2
+instruction extensions. See accompanying INSTALL file and
+OPENSSL_ia32cap(3) documentation page for further information.
+
+* Why does compiler fail to compile sha512.c?
+
+OpenSSL SHA-512 implementation depends on compiler support for 64-bit
+integer type. Few elder compilers [ULTRIX cc, SCO compiler to mention a
+couple] lack support for this and therefore are incapable of compiling
+the module in question. The recommendation is to disable SHA-512 by
+adding no-sha512 to ./config [or ./Configure] command line. Another
+possible alternative might be to switch to GCC.
+
+* Test suite still fails, what to do?
+
+Another common reason for failure to complete some particular test is
+simply bad code generated by a buggy component in toolchain or deficiency
+in run-time environment. There are few cases documented in PROBLEMS file,
+consult it for possible workaround before you beat the drum. Even if you
+don't find solution or even mention there, do reserve for possibility of
+a compiler bug. Compiler bugs might appear in rather bizarre ways, they
+never make sense, and tend to emerge when you least expect them. In order
+to identify one, drop optimization level, e.g. by editing CFLAG line in
+top-level Makefile, recompile and re-run the test.
+
+* I think I've found a bug, what should I do?
+
+If you are a new user then it is quite likely you haven't found a bug and
+something is happening you aren't familiar with. Check this FAQ, the associated
+documentation and the mailing lists for similar queries. If you are still
+unsure whether it is a bug or not submit a query to the openssl-users mailing
+list.
+
+
+* I'm SURE I've found a bug, how do I report it?
+
+Bug reports with no security implications should be sent to the request
+tracker. This can be done by mailing the report to <rt@openssl.org> (or its
+alias <openssl-bugs@openssl.org>), please note that messages sent to the
+request tracker also appear in the public openssl-dev mailing list.
+
+The report should be in plain text. Any patches should be sent as
+plain text attachments because some mailers corrupt patches sent inline.
+If your issue affects multiple versions of OpenSSL check any patches apply
+cleanly and, if possible include patches to each affected version.
+
+The report should be given a meaningful subject line briefly summarising the
+issue. Just "bug in OpenSSL" or "bug in OpenSSL 0.9.8n" is not very helpful.
+
+By sending reports to the request tracker the bug can then be given a priority
+and assigned to the appropriate maintainer. The history of discussions can be
+accessed and if the issue has been addressed or a reason why not. If patches
+are only sent to openssl-dev they can be mislaid if a team member has to
+wade through months of old messages to review the discussion.
+
+See also <URL: http://www.openssl.org/support/rt.html>
+
+
+* I've found a security issue, how do I report it?
+
+If you think your bug has security implications then please send it to
+openssl-security@openssl.org if you don't get a prompt reply at least
+acknowledging receipt then resend or mail it directly to one of the
+more active team members (e.g. Steve).
[PROG] ========================================================================
file.
Multi-threaded applications must provide two callback functions to
-OpenSSL. This is described in the threads(3) manpage.
-
+OpenSSL by calling CRYPTO_set_locking_callback() and
+CRYPTO_set_id_callback(), for all versions of OpenSSL up to and
+including 0.9.8[abc...]. As of version 1.0.0, CRYPTO_set_id_callback()
+and associated APIs are deprecated by CRYPTO_THREADID_set_callback()
+and friends. This is described in the threads(3) manpage.
* I've compiled a program under Windows and it crashes: why?
-This is usually because you've missed the comment in INSTALL.W32. You
-must link with the multithreaded DLL version of the VC++ runtime library
-otherwise the conflict will cause a program to crash: typically on the
-first BIO related read or write operation.
-
+This is usually because you've missed the comment in INSTALL.W32.
+Your application must link against the same version of the Win32
+C-Runtime against which your openssl libraries were linked. The
+default version for OpenSSL is /MD - "Multithreaded DLL".
+
+If you are using Microsoft Visual C++'s IDE (Visual Studio), in
+many cases, your new project most likely defaulted to "Debug
+Singlethreaded" - /ML. This is NOT interchangeable with /MD and your
+program will crash, typically on the first BIO related read or write
+operation.
+
+For each of the six possible link stage configurations within Win32,
+your application must link against the same by which OpenSSL was
+built. If you are using MS Visual C++ (Studio) this can be changed
+by:
+
+ 1. Select Settings... from the Project Menu.
+ 2. Select the C/C++ Tab.
+ 3. Select "Code Generation from the "Category" drop down list box
+ 4. Select the Appropriate library (see table below) from the "Use
+ run-time library" drop down list box. Perform this step for both
+ your debug and release versions of your application (look at the
+ top left of the settings panel to change between the two)
+
+ Single Threaded /ML - MS VC++ often defaults to
+ this for the release
+ version of a new project.
+ Debug Single Threaded /MLd - MS VC++ often defaults to
+ this for the debug version
+ of a new project.
+ Multithreaded /MT
+ Debug Multithreaded /MTd
+ Multithreaded DLL /MD - OpenSSL defaults to this.
+ Debug Multithreaded DLL /MDd
+
+Note that debug and release libraries are NOT interchangeable. If you
+built OpenSSL with /MD your application must use /MD and cannot use /MDd.
+
+As per 0.9.8 the above limitation is eliminated for .DLLs. OpenSSL
+.DLLs compiled with some specific run-time option [we insist on the
+default /MD] can be deployed with application compiled with different
+option or even different compiler. But there is a catch! Instead of
+re-compiling OpenSSL toolkit, as you would have to with prior versions,
+you have to compile small C snippet with compiler and/or options of
+your choice. The snippet gets installed as
+<install-root>/include/openssl/applink.c and should be either added to
+your application project or simply #include-d in one [and only one]
+of your application source files. Failure to link this shim module
+into your application manifests itself as fatal "no OPENSSL_Applink"
+run-time error. An explicit reminder is due that in this situation
+[mixing compiler options] it is as important to add CRYPTO_malloc_init
+prior first call to OpenSSL.
* How do I read or write a DER encoded buffer using the ASN1 functions?
You have two options. You can either use a memory BIO in conjunction
-with the i2d_XXX_bio() or d2i_XXX_bio() functions or you can use the
-i2d_XXX(), d2i_XXX() functions directly. Since these are often the
+with the i2d_*_bio() or d2i_*_bio() functions or you can use the
+i2d_*(), d2i_*() functions directly. Since these are often the
cause of grief here are some code fragments using PKCS7 as an example:
-unsigned char *buf, *p;
-int len;
+ unsigned char *buf, *p;
+ int len;
-len = i2d_PKCS7(p7, NULL);
-buf = OPENSSL_malloc(len); /* or Malloc, error checking omitted */
-p = buf;
-i2d_PKCS7(p7, &p);
+ len = i2d_PKCS7(p7, NULL);
+ buf = OPENSSL_malloc(len); /* or Malloc, error checking omitted */
+ p = buf;
+ i2d_PKCS7(p7, &p);
At this point buf contains the len bytes of the DER encoding of
p7.
The opposite assumes we already have len bytes in buf:
-unsigned char *p;
-p = buf;
-p7 = d2i_PKCS7(NULL, &p, len);
+ unsigned char *p;
+ p = buf;
+ p7 = d2i_PKCS7(NULL, &p, len);
-At this point p7 contains a valid PKCS7 structure of NULL if an error
+At this point p7 contains a valid PKCS7 structure or NULL if an error
occurred. If an error occurred ERR_print_errors(bio) should give more
information.
and attempts to free the buffer will have unpredictable results
because it no longer points to the same address.
+Memory allocation and encoding can also be combined in a single
+operation by the ASN1 routines:
+
+ unsigned char *buf = NULL; /* mandatory */
+ int len;
+ len = i2d_PKCS7(p7, &buf);
+ if (len < 0)
+ /* Error */
+ /* Do some things with 'buf' */
+ /* Finished with buf: free it */
+ OPENSSL_free(buf);
+
+In this special case the "buf" parameter is *not* incremented, it points
+to the start of the encoding.
+
+
+* OpenSSL uses DER but I need BER format: does OpenSSL support BER?
+
+The short answer is yes, because DER is a special case of BER and OpenSSL
+ASN1 decoders can process BER.
+
+The longer answer is that ASN1 structures can be encoded in a number of
+different ways. One set of ways is the Basic Encoding Rules (BER) with various
+permissible encodings. A restriction of BER is the Distinguished Encoding
+Rules (DER): these uniquely specify how a given structure is encoded.
+
+Therefore, because DER is a special case of BER, DER is an acceptable encoding
+for BER.
+
* I've tried using <M_some_evil_pkcs12_macro> and I get errors why?
* Why do I get errors about unknown algorithms?
-This can happen under several circumstances such as reading in an
-encrypted private key or attempting to decrypt a PKCS#12 file. The cause
-is forgetting to load OpenSSL's table of algorithms with
-OpenSSL_add_all_algorithms(). See the manual page for more information.
-
+The cause is forgetting to load OpenSSL's table of algorithms with
+OpenSSL_add_all_algorithms(). See the manual page for more information. This
+can cause several problems such as being unable to read in an encrypted
+PEM file, unable to decrypt a PKCS#12 file or signature failure when
+verifying certificates.
* Why can't the OpenSSH configure script detect OpenSSL?
the OpenSSH configure script. It should contain the detailed information
on why the OpenSSL library was not detected or considered incompatible.
+
* Can I use OpenSSL's SSL library with non-blocking I/O?
Yes; make sure to read the SSL_get_error(3) manual page!
* Why doesn't my server application receive a client certificate?
Due to the TLS protocol definition, a client will only send a certificate,
-if explicitely asked by the server. Use the SSL_VERIFY_PEER flag of the
+if explicitly asked by the server. Use the SSL_VERIFY_PEER flag of the
SSL_CTX_set_verify() function to enable the use of client certificates.
-===============================================================================
+* Why does compilation fail due to an undefined symbol NID_uniqueIdentifier?
+
+For OpenSSL 0.9.7 the OID table was extended and corrected. In earlier
+versions, uniqueIdentifier was incorrectly used for X.509 certificates.
+The correct name according to RFC2256 (LDAP) is x500UniqueIdentifier.
+Change your code to use the new name when compiling against OpenSSL 0.9.7.
+
+
+* I think I've detected a memory leak, is this a bug?
+
+In most cases the cause of an apparent memory leak is an OpenSSL internal table
+that is allocated when an application starts up. Since such tables do not grow
+in size over time they are harmless.
+
+These internal tables can be freed up when an application closes using various
+functions. Currently these include following:
+
+Thread-local cleanup functions:
+ ERR_remove_state()
+
+Application-global cleanup functions that are aware of usage (and therefore
+thread-safe):
+
+ ENGINE_cleanup() and CONF_modules_unload()
+
+"Brutal" (thread-unsafe) Application-global cleanup functions:
+
+ ERR_free_strings(), EVP_cleanup() and CRYPTO_cleanup_all_ex_data().
+
+
+* Why does Valgrind complain about the use of uninitialized data?
+
+When OpenSSL's PRNG routines are called to generate random numbers the supplied
+buffer contents are mixed into the entropy pool: so it technically does not
+matter whether the buffer is initialized at this point or not. Valgrind (and
+other test tools) will complain about this. When using Valgrind, make sure the
+OpenSSL library has been compiled with the PURIFY macro defined (-DPURIFY)
+to get rid of these warnings.
+
+
+* Why doesn't a memory BIO work when a file does?
+
+This can occur in several cases for example reading an S/MIME email message.
+The reason is that a memory BIO can do one of two things when all the data
+has been read from it.
+
+The default behaviour is to indicate that no more data is available and that
+the call should be retried, this is to allow the application to fill up the BIO
+again if necessary.
+
+Alternatively it can indicate that no more data is available and that EOF has
+been reached.
+
+If a memory BIO is to behave in the same way as a file this second behaviour
+is needed. This must be done by calling:
+
+ BIO_set_mem_eof_return(bio, 0);
+
+See the manual pages for more details.
+
+
+* Where are the declarations and implementations of d2i_X509() etc?
+
+These are defined and implemented by macros of the form:
+
+
+ DECLARE_ASN1_FUNCTIONS(X509) and IMPLEMENT_ASN1_FUNCTIONS(X509)
+
+The implementation passes an ASN1 "template" defining the structure into an
+ASN1 interpreter using generalised functions such as ASN1_item_d2i().
+
+
+===============================================================================
projects / openssl.git / blobdiff