diff options
Diffstat (limited to 'crypto/openssl/FAQ')
| -rw-r--r-- | crypto/openssl/FAQ | 1039 |
1 files changed, 1039 insertions, 0 deletions
diff --git a/crypto/openssl/FAQ b/crypto/openssl/FAQ new file mode 100644 index 0000000..f8ea604 --- /dev/null +++ b/crypto/openssl/FAQ @@ -0,0 +1,1039 @@ +OpenSSL - Frequently Asked Questions +-------------------------------------- + +[MISC] Miscellaneous questions + +* Which is the current version of OpenSSL? +* Where is the documentation? +* How can I contact the OpenSSL developers? +* 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 + +* Do I need patent licenses to use OpenSSL? +* Can I use OpenSSL with GPL software? + +[USER] Questions on using the OpenSSL applications + +* Why do I get a "PRNG not seeded" error message? +* Why do I get an "unable to write 'random state'" error message? +* How do I create certificates or certificate requests? +* Why can't I create certificate requests? +* Why does <SSL program> fail with a certificate verify error? +* Why can I only use weak ciphers when I connect to a server using OpenSSL? +* How can I create DSA certificates? +* Why can't I make an SSL connection using a DSA certificate? +* 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? + +[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 do I get errors about unknown algorithms? +* 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? + +=============================================================================== + +[MISC] ======================================================================== + +* Which is the current version of OpenSSL? + +The current version is available from <URL: http://www.openssl.org>. +OpenSSL 1.0.1e was released on Feb 11th, 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 Git access. + + +* Where is the documentation? + +OpenSSL is a library that provides cryptographic functionality to +applications such as secure web servers. Be sure to read the +documentation of the application you want to use. The INSTALL file +explains how to install this library. + +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. 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/>. 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. + +There is some documentation about certificate extensions and PKCS#12 +in doc/openssl.txt + +The original SSLeay documentation is included in OpenSSL as +doc/ssleay.txt. It may be useful when none of the other resources +help, but please note that it reflects the obsolete version SSLeay +0.6.6. + + +* How can I contact the OpenSSL developers? + +The README file describes how to submit bug reports and patches to +OpenSSL. Information on the OpenSSL mailing lists is available from +<URL: http://www.openssl.org>. + + +* 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 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. + +A number of Linux and *BSD distributions include OpenSSL. + + +* Why aren't tools like 'autoconf' and 'libtool' used? + +autoconf will probably be used in future OpenSSL versions. If it was +less Unix-centric, it might have been used much earlier. + +* What is an 'engine' version? + +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 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. + +[LEGAL] ======================================================================= + +* Do I need patent licenses to use OpenSSL? + +The patents section of the README file lists patents that may apply to +you if you want to use OpenSSL. For information on intellectual +property rights, please consult a lawyer. The OpenSSL team does not +offer legal advice. + +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? + +On many systems including the major Linux and BSD distributions, yes (the +GPL does not place restrictions on using libraries that are part of the +normal operating system distribution). + +On other systems, the situation is less clear. Some GPL software copyright +holders claim that you infringe on their rights if you use OpenSSL with +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 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 +for permission to use their software with OpenSSL. + + +[USER] ======================================================================== + +* Why do I get a "PRNG not seeded" error message? + +Cryptographic software needs a source of unpredictable data to work +correctly. Many open source operating systems provide a "randomness +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 +details. Starting with version 0.9.7, OpenSSL will automatically look +for an EGD socket at /var/run/egd-pool, /dev/egd-pool, /etc/egd-pool and +/etc/entropy. + +Most components of the openssl command line utility automatically try +to seed the random number generator from a file. The name of the +default seeding file is determined as follows: If environment variable +RANDFILE is set, then it names the seeding file. Otherwise if +environment variable HOME is set, then the seeding file is $HOME/.rnd. +If neither RANDFILE nor HOME is set, versions up to OpenSSL 0.9.6 will +use file .rnd in the current directory while OpenSSL 0.9.6a uses no +default seeding file at all. OpenSSL 0.9.6b and later will behave +similarly to 0.9.6a, but will use a default of "C:\" for HOME on +Windows systems if the environment variable has not been set. + +If the default seeding file does not exist or is too short, the "PRNG +not seeded" error message may occur. + +The openssl command line utility will write back a new state to the +default seeding file (and create this file if necessary) unless +there was no sufficient seeding. + +Pointing $RANDFILE to an Entropy Gathering Daemon socket does not work. +Use the "-rand" option of the OpenSSL command line tools instead. +The $RANDFILE environment variable and $HOME/.rnd are only used by the +OpenSSL command line tools. Applications using the OpenSSL library +provide their own configuration options to specify the entropy source, +please check out the documentation coming the with application. + + +* Why do I get an "unable to write 'random state'" error message? + + +Sometimes the openssl command line utility does not abort with +a "PRNG not seeded" error message, but complains that it is +"unable to write 'random state'". This message refers to the +default seeding file (see previous answer). A possible reason +is that no default filename is known because neither RANDFILE +nor HOME is set. (Versions up to 0.9.6 used file ".rnd" in the +current directory in this case, but this has changed with 0.9.6a.) + + +* How do I create certificates or certificate requests? + +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 (in ca(1), req(1), x509v3_config(5) ) + + +* Why can't I create certificate requests? + +You typically get the error: + + unable to find 'distinguished_name' in config + problems making Certificate Request + +This is because it can't find the configuration file. Check out the +DIAGNOSTICS section of req(1) for more information. + + +* Why does <SSL program> fail with a certificate verify error? + +This problem is usually indicated by log messages saying something like +"unable to get local issuer certificate" or "self signed certificate". +When a certificate is verified its root CA must be "trusted" by OpenSSL +this typically means that the CA certificate must be placed in a directory +or file and the relevant program configured to read it. The OpenSSL program +'verify' behaves in a similar way and issues similar error messages: check +the verify(1) program manual page for more information. + + +* Why can I only use weak ciphers when I connect to a server using OpenSSL? + +This is almost certainly because you are using an old "export grade" browser +which only supports weak encryption. Upgrade your browser to support 128 bit +ciphers. + + +* How can I create DSA certificates? + +Check the CA.pl(1) manual page for a DSA certificate example. + + +* Why can't I make an SSL connection to a server using a DSA certificate? + +Typically you'll see a message saying there are no shared ciphers when +the same setup works fine with an RSA certificate. There are two possible +causes. The client may not support connections to DSA servers most web +browsers (including Netscape and MSIE) only support connections to servers +supporting RSA cipher suites. The other cause is that a set of DH parameters +has not been supplied to the server. DH parameters can be created with the +dhparam(1) command and loaded using the SSL_CTX_set_tmp_dh() for example: +check the source to s_server in apps/s_server.c for an example. + + +* How can I remove the passphrase on a private key? + +Firstly you should be really *really* sure you want to do this. Leaving +a private key unencrypted is a major security risk. If you decide that +you do have to do this check the EXAMPLES sections of the rsa(1) and +dsa(1) manual pages. + + +* Why can't I use OpenSSL certificates with SSL client authentication? + +What will typically happen is that when a server requests authentication +it will either not include your certificate or tell you that you have +no client certificates (Netscape) or present you with an empty list box +(MSIE). The reason for this is that when a server requests a client +certificate it includes a list of CAs names which it will accept. Browsers +will only let you select certificates from the list on the grounds that +there is little point presenting a certificate which the server will +reject. + +The solution is to add the relevant CA certificate to your servers "trusted +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 + +If your server only requests certificates on certain URLs then you may need +to manually issue an HTTP GET command to get the list when s_client connects: + +GET /some/page/needing/a/certificate.html + +If your CA does not appear in the list then this confirms the problem. + + +* Why does my browser give a warning about a mismatched hostname? + +Browsers expect the server's hostname to match the value in the commonName +(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> + + +[BUILD] ======================================================================= + +* Why does the linker complain about undefined symbols? + +Maybe the compilation was interrupted, and make doesn't notice that +something is missing. Run "make clean; make". + +If you used ./Configure instead of ./config, make sure that you +selected the right target. File formats may differ slightly between +OS versions (for example sparcv8/sparcv9, or a.out/elf). + +In case you get errors about the following symbols, use the config +option "no-asm", as described in INSTALL: + + BF_cbc_encrypt, BF_decrypt, BF_encrypt, CAST_cbc_encrypt, + CAST_decrypt, CAST_encrypt, RC4, RC5_32_cbc_encrypt, RC5_32_decrypt, + RC5_32_encrypt, bn_add_words, bn_div_words, bn_mul_add_words, + bn_mul_comba4, bn_mul_comba8, bn_mul_words, bn_sqr_comba4, + bn_sqr_comba8, bn_sqr_words, bn_sub_words, des_decrypt3, + des_ede3_cbc_encrypt, des_encrypt, des_encrypt2, des_encrypt3, + des_ncbc_encrypt, md5_block_asm_host_order, sha1_block_asm_data_order + +If none of these helps, you may want to try using the current snapshot. +If the problem persists, please submit a bug report. + + +* Why does the OpenSSL test fail with "bc: command not found"? + +You didn't install "bc", the Unix calculator. If you want to run the +tests, get GNU bc from ftp://ftp.gnu.org or from your OS distributor. + + +* Why does the OpenSSL test fail with "bc: 1 no implemented"? + +On some SCO installations or versions, bc has a bug that gets triggered +when you run the test suite (using "make test"). The message returned is +"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 <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. + + +* Why does the OpenSSL compilation fail on Alpha Tru64 Unix? + +On some Alpha installations running Tru64 Unix and Compaq C, the compilation +of crypto/sha/sha_dgst.c fails with the message 'Fatal: Insufficient virtual +memory to continue compilation.' As far as the tests have shown, this may be +a compiler bug. What happens is that it eats up a lot of resident memory +to build something, probably a table. The problem is clearly in the +optimization code, because if one eliminates optimization completely (-O0), +the compilation goes through (and the compiler consumes about 2MB of resident +memory instead of 240MB or whatever one's limit is currently). + +There are three options to solve this problem: + +1. set your current data segment size soft limit higher. Experience shows +that about 241000 kbytes seems to be enough on an AlphaServer DS10. You do +this with the command 'ulimit -Sd nnnnnn', where 'nnnnnn' is the number of +kbytes to set the limit to. + +2. If you have a hard limit that is lower than what you need and you can't +get it changed, you can compile all of OpenSSL with -O0 as optimization +level. This is however not a very nice thing to do for those who expect to +get the best result from OpenSSL. A bit more complicated solution is the +following: + +----- snip:start ----- + make DIRS=crypto SDIRS=sha "`grep '^CFLAG=' Makefile.ssl | \ + sed -e 's/ -O[0-9] / -O0 /'`" + rm `ls crypto/*.o crypto/sha/*.o | grep -v 'sha_dgst\.o'` + make +----- snip:end ----- + +This will only compile sha_dgst.c with -O0, the rest with the optimization +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"? + +Getting this message is quite usual on Solaris 2, because Sun has hidden +away 'ar' and other development commands in directories that aren't in +$PATH by default. One of those directories is '/usr/ccs/bin'. The +quickest way to fix this is to do the following (it assumes you use sh +or any sh-compatible shell): + +----- snip:start ----- + PATH=${PATH}:/usr/ccs/bin; export PATH +----- snip:end ----- + +and then redo the compilation. What you should really do is make sure +'/usr/ccs/bin' is permanently in your $PATH, for example through your +'.profile' (again, assuming you use a sh-compatible shell). + + +* Why does the OpenSSL compilation fail on Win32 with VC++? + +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 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 extentions. 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). + +Note that bugs only present in the openssl utility are not in general +considered to be security issues. + +[PROG] ======================================================================== + +* Is OpenSSL thread-safe? + +Yes (with limitations: an SSL connection may not concurrently be used +by multiple threads). On Windows and many Unix systems, OpenSSL +automatically uses the multi-threaded versions of the standard +libraries. If your platform is not one of these, consult the INSTALL +file. + +Multi-threaded applications must provide two callback functions to +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. +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_*_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; + + 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); + +At this point p7 contains a valid PKCS7 structure of NULL if an error +occurred. If an error occurred ERR_print_errors(bio) should give more +information. + +The reason for the temporary variable 'p' is that the ASN1 functions +increment the passed pointer so it is ready to read or write the next +structure. This is often a cause of problems: without the temporary +variable the buffer pointer is changed to point just after the data +that has been read or written. This may well be uninitialized data +and attempts to free the buffer will have unpredictable results +because it no longer points to the same address. + + +* 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? + +This usually happens when you try compiling something using the PKCS#12 +macros with a C++ compiler. There is hardly ever any need to use the +PKCS#12 macros in a program, it is much easier to parse and create +PKCS#12 files using the PKCS12_parse() and PKCS12_create() functions +documented in doc/openssl.txt and with examples in demos/pkcs12. The +'pkcs12' application has to use the macros because it prints out +debugging information. + + +* I've called <some function> and it fails, why? + +Before submitting a report or asking in one of the mailing lists, you +should try to determine the cause. In particular, you should call +ERR_print_errors() or ERR_print_errors_fp() after the failed call +and see if the message helps. Note that the problem may occur earlier +than you think -- you should check for errors after every call where +it is possible, otherwise the actual problem may be hidden because +some OpenSSL functions clear the error state. + + +* I just get a load of numbers for the error output, what do they mean? + +The actual format is described in the ERR_print_errors() manual page. +You should call the function ERR_load_crypto_strings() before hand and +the message will be output in text form. If you can't do this (for example +it is a pre-compiled binary) you can use the errstr utility on the error +code itself (the hex digits after the second colon). + + +* Why do I get errors about unknown algorithms? + +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? + +Several reasons for problems with the automatic detection exist. +OpenSSH requires at least version 0.9.5a of the OpenSSL libraries. +Sometimes the distribution has installed an older version in the system +locations that is detected instead of a new one installed. The OpenSSL +library might have been compiled for another CPU or another mode (32/64 bits). +Permissions might be wrong. + +The general answer is to check the config.log file generated when running +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! + +A pitfall to avoid: Don't assume that SSL_read() will just read from +the underlying transport or that SSL_write() will just write to it -- +it is also possible that SSL_write() cannot do any useful work until +there is data to read, or that SSL_read() cannot do anything until it +is possible to send data. One reason for this is that the peer may +request a new TLS/SSL handshake at any time during the protocol, +requiring a bi-directional message exchange; both SSL_read() and +SSL_write() will try to continue any pending handshake. + + +* Why doesn't my server application receive a client certificate? + +Due to the TLS protocol definition, a client will only send a certificate, +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(). + + +=============================================================================== |
