FAQ revision 162911
1OpenSSL - Frequently Asked Questions 2-------------------------------------- 3 4[MISC] Miscellaneous questions 5 6* Which is the current version of OpenSSL? 7* Where is the documentation? 8* How can I contact the OpenSSL developers? 9* Where can I get a compiled version of OpenSSL? 10* Why aren't tools like 'autoconf' and 'libtool' used? 11* What is an 'engine' version? 12* How do I check the authenticity of the OpenSSL distribution? 13 14[LEGAL] Legal questions 15 16* Do I need patent licenses to use OpenSSL? 17* Can I use OpenSSL with GPL software? 18 19[USER] Questions on using the OpenSSL applications 20 21* Why do I get a "PRNG not seeded" error message? 22* Why do I get an "unable to write 'random state'" error message? 23* How do I create certificates or certificate requests? 24* Why can't I create certificate requests? 25* Why does <SSL program> fail with a certificate verify error? 26* Why can I only use weak ciphers when I connect to a server using OpenSSL? 27* How can I create DSA certificates? 28* Why can't I make an SSL connection using a DSA certificate? 29* How can I remove the passphrase on a private key? 30* Why can't I use OpenSSL certificates with SSL client authentication? 31* Why does my browser give a warning about a mismatched hostname? 32* How do I install a CA certificate into a browser? 33* Why is OpenSSL x509 DN output not conformant to RFC2253? 34* What is a "128 bit certificate"? Can I create one with OpenSSL? 35 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? 52* Test suite still fails, what to do? 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? 69 70=============================================================================== 71 72[MISC] ======================================================================== 73 74* Which is the current version of OpenSSL? 75 76The current version is available from <URL: http://www.openssl.org>. 77OpenSSL 0.9.8d was released on September 28th, 2006. 78 79In addition to the current stable release, you can also access daily 80snapshots of the OpenSSL development version at <URL: 81ftp://ftp.openssl.org/snapshot/>, or get it by anonymous CVS access. 82 83 84* Where is the documentation? 85 86OpenSSL is a library that provides cryptographic functionality to 87applications such as secure web servers. Be sure to read the 88documentation of the application you want to use. The INSTALL file 89explains how to install this library. 90 91OpenSSL includes a command line utility that can be used to perform a 92variety of cryptographic functions. It is described in the openssl(1) 93manpage. Documentation for developers is currently being written. A 94few manual pages already are available; overviews over libcrypto and 95libssl are given in the crypto(3) and ssl(3) manpages. 96 97The OpenSSL manpages are installed in /usr/local/ssl/man/ (or a 98different directory if you specified one as described in INSTALL). 99In addition, you can read the most current versions at 100<URL: http://www.openssl.org/docs/>. 101 102For information on parts of libcrypto that are not yet documented, you 103might want to read Ariel Glenn's documentation on SSLeay 0.9, OpenSSL's 104predecessor, at <URL: http://www.columbia.edu/~ariel/ssleay/>. Much 105of this still applies to OpenSSL. 106 107There is some documentation about certificate extensions and PKCS#12 108in doc/openssl.txt 109 110The original SSLeay documentation is included in OpenSSL as 111doc/ssleay.txt. It may be useful when none of the other resources 112help, but please note that it reflects the obsolete version SSLeay 1130.6.6. 114 115 116* How can I contact the OpenSSL developers? 117 118The README file describes how to submit bug reports and patches to 119OpenSSL. Information on the OpenSSL mailing lists is available from 120<URL: http://www.openssl.org>. 121 122 123* Where can I get a compiled version of OpenSSL? 124 125You can finder pointers to binary distributions in 126http://www.openssl.org/related/binaries.html . 127 128Some applications that use OpenSSL are distributed in binary form. 129When using such an application, you don't need to install OpenSSL 130yourself; the application will include the required parts (e.g. DLLs). 131 132If you want to build OpenSSL on a Windows system and you don't have 133a C compiler, read the "Mingw32" section of INSTALL.W32 for information 134on how to obtain and install the free GNU C compiler. 135 136A number of Linux and *BSD distributions include OpenSSL. 137 138 139* Why aren't tools like 'autoconf' and 'libtool' used? 140 141autoconf will probably be used in future OpenSSL versions. If it was 142less Unix-centric, it might have been used much earlier. 143 144* What is an 'engine' version? 145 146With version 0.9.6 OpenSSL was extended to interface to external crypto 147hardware. This was realized in a special release '0.9.6-engine'. With 148version 0.9.7 the changes were merged into the main development line, 149so that the special release is no longer necessary. 150 151* How do I check the authenticity of the OpenSSL distribution? 152 153We provide MD5 digests and ASC signatures of each tarball. 154Use MD5 to check that a tarball from a mirror site is identical: 155 156 md5sum TARBALL | awk '{print $1;}' | cmp - TARBALL.md5 157 158You can check authenticity using pgp or gpg. You need the OpenSSL team 159member public key used to sign it (download it from a key server, see a 160list of keys at <URL: http://www.openssl.org/about/>). Then 161just do: 162 163 pgp TARBALL.asc 164 165[LEGAL] ======================================================================= 166 167* Do I need patent licenses to use OpenSSL? 168 169The patents section of the README file lists patents that may apply to 170you if you want to use OpenSSL. For information on intellectual 171property rights, please consult a lawyer. The OpenSSL team does not 172offer legal advice. 173 174You can configure OpenSSL so as not to use IDEA, MDC2 and RC5 by using 175 ./config no-idea no-mdc2 no-rc5 176 177 178* Can I use OpenSSL with GPL software? 179 180On many systems including the major Linux and BSD distributions, yes (the 181GPL does not place restrictions on using libraries that are part of the 182normal operating system distribution). 183 184On other systems, the situation is less clear. Some GPL software copyright 185holders claim that you infringe on their rights if you use OpenSSL with 186their software on operating systems that don't normally include OpenSSL. 187 188If you develop open source software that uses OpenSSL, you may find it 189useful to choose an other license than the GPL, or state explicitly that 190"This program is released under the GPL with the additional exemption that 191compiling, linking, and/or using OpenSSL is allowed." If you are using 192GPL software developed by others, you may want to ask the copyright holder 193for permission to use their software with OpenSSL. 194 195 196[USER] ======================================================================== 197 198* Why do I get a "PRNG not seeded" error message? 199 200Cryptographic software needs a source of unpredictable data to work 201correctly. Many open source operating systems provide a "randomness 202device" (/dev/urandom or /dev/random) that serves this purpose. 203All OpenSSL versions try to use /dev/urandom by default; starting with 204version 0.9.7, OpenSSL also tries /dev/random if /dev/urandom is not 205available. 206 207On other systems, applications have to call the RAND_add() or 208RAND_seed() function with appropriate data before generating keys or 209performing public key encryption. (These functions initialize the 210pseudo-random number generator, PRNG.) Some broken applications do 211not do this. As of version 0.9.5, the OpenSSL functions that need 212randomness report an error if the random number generator has not been 213seeded with at least 128 bits of randomness. If this error occurs and 214is not discussed in the documentation of the application you are 215using, please contact the author of that application; it is likely 216that it never worked correctly. OpenSSL 0.9.5 and later make the 217error visible by refusing to perform potentially insecure encryption. 218 219If you are using Solaris 8, you can add /dev/urandom and /dev/random 220devices by installing patch 112438 (Sparc) or 112439 (x86), which are 221available via the Patchfinder at <URL: http://sunsolve.sun.com> 222(Solaris 9 includes these devices by default). For /dev/random support 223for earlier Solaris versions, see Sun's statement at 224<URL: http://sunsolve.sun.com/pub-cgi/retrieve.pl?doc=fsrdb/27606&zone_32=SUNWski> 225(the SUNWski package is available in patch 105710). 226 227On systems without /dev/urandom and /dev/random, it is a good idea to 228use the Entropy Gathering Demon (EGD); see the RAND_egd() manpage for 229details. Starting with version 0.9.7, OpenSSL will automatically look 230for an EGD socket at /var/run/egd-pool, /dev/egd-pool, /etc/egd-pool and 231/etc/entropy. 232 233Most components of the openssl command line utility automatically try 234to seed the random number generator from a file. The name of the 235default seeding file is determined as follows: If environment variable 236RANDFILE is set, then it names the seeding file. Otherwise if 237environment variable HOME is set, then the seeding file is $HOME/.rnd. 238If neither RANDFILE nor HOME is set, versions up to OpenSSL 0.9.6 will 239use file .rnd in the current directory while OpenSSL 0.9.6a uses no 240default seeding file at all. OpenSSL 0.9.6b and later will behave 241similarly to 0.9.6a, but will use a default of "C:\" for HOME on 242Windows systems if the environment variable has not been set. 243 244If the default seeding file does not exist or is too short, the "PRNG 245not seeded" error message may occur. 246 247The openssl command line utility will write back a new state to the 248default seeding file (and create this file if necessary) unless 249there was no sufficient seeding. 250 251Pointing $RANDFILE to an Entropy Gathering Daemon socket does not work. 252Use the "-rand" option of the OpenSSL command line tools instead. 253The $RANDFILE environment variable and $HOME/.rnd are only used by the 254OpenSSL command line tools. Applications using the OpenSSL library 255provide their own configuration options to specify the entropy source, 256please check out the documentation coming the with application. 257 258 259* Why do I get an "unable to write 'random state'" error message? 260 261 262Sometimes the openssl command line utility does not abort with 263a "PRNG not seeded" error message, but complains that it is 264"unable to write 'random state'". This message refers to the 265default seeding file (see previous answer). A possible reason 266is that no default filename is known because neither RANDFILE 267nor HOME is set. (Versions up to 0.9.6 used file ".rnd" in the 268current directory in this case, but this has changed with 0.9.6a.) 269 270 271* How do I create certificates or certificate requests? 272 273Check out the CA.pl(1) manual page. This provides a simple wrapper round 274the 'req', 'verify', 'ca' and 'pkcs12' utilities. For finer control check 275out the manual pages for the individual utilities and the certificate 276extensions documentation (currently in doc/openssl.txt). 277 278 279* Why can't I create certificate requests? 280 281You typically get the error: 282 283 unable to find 'distinguished_name' in config 284 problems making Certificate Request 285 286This is because it can't find the configuration file. Check out the 287DIAGNOSTICS section of req(1) for more information. 288 289 290* Why does <SSL program> fail with a certificate verify error? 291 292This problem is usually indicated by log messages saying something like 293"unable to get local issuer certificate" or "self signed certificate". 294When a certificate is verified its root CA must be "trusted" by OpenSSL 295this typically means that the CA certificate must be placed in a directory 296or file and the relevant program configured to read it. The OpenSSL program 297'verify' behaves in a similar way and issues similar error messages: check 298the verify(1) program manual page for more information. 299 300 301* Why can I only use weak ciphers when I connect to a server using OpenSSL? 302 303This is almost certainly because you are using an old "export grade" browser 304which only supports weak encryption. Upgrade your browser to support 128 bit 305ciphers. 306 307 308* How can I create DSA certificates? 309 310Check the CA.pl(1) manual page for a DSA certificate example. 311 312 313* Why can't I make an SSL connection to a server using a DSA certificate? 314 315Typically you'll see a message saying there are no shared ciphers when 316the same setup works fine with an RSA certificate. There are two possible 317causes. The client may not support connections to DSA servers most web 318browsers (including Netscape and MSIE) only support connections to servers 319supporting RSA cipher suites. The other cause is that a set of DH parameters 320has not been supplied to the server. DH parameters can be created with the 321dhparam(1) command and loaded using the SSL_CTX_set_tmp_dh() for example: 322check the source to s_server in apps/s_server.c for an example. 323 324 325* How can I remove the passphrase on a private key? 326 327Firstly you should be really *really* sure you want to do this. Leaving 328a private key unencrypted is a major security risk. If you decide that 329you do have to do this check the EXAMPLES sections of the rsa(1) and 330dsa(1) manual pages. 331 332 333* Why can't I use OpenSSL certificates with SSL client authentication? 334 335What will typically happen is that when a server requests authentication 336it will either not include your certificate or tell you that you have 337no client certificates (Netscape) or present you with an empty list box 338(MSIE). The reason for this is that when a server requests a client 339certificate it includes a list of CAs names which it will accept. Browsers 340will only let you select certificates from the list on the grounds that 341there is little point presenting a certificate which the server will 342reject. 343 344The solution is to add the relevant CA certificate to your servers "trusted 345CA list". How you do this depends on the server software in uses. You can 346print out the servers list of acceptable CAs using the OpenSSL s_client tool: 347 348openssl s_client -connect www.some.host:443 -prexit 349 350If your server only requests certificates on certain URLs then you may need 351to manually issue an HTTP GET command to get the list when s_client connects: 352 353GET /some/page/needing/a/certificate.html 354 355If your CA does not appear in the list then this confirms the problem. 356 357 358* Why does my browser give a warning about a mismatched hostname? 359 360Browsers expect the server's hostname to match the value in the commonName 361(CN) field of the certificate. If it does not then you get a warning. 362 363 364* How do I install a CA certificate into a browser? 365 366The usual way is to send the DER encoded certificate to the browser as 367MIME type application/x-x509-ca-cert, for example by clicking on an appropriate 368link. On MSIE certain extensions such as .der or .cacert may also work, or you 369can import the certificate using the certificate import wizard. 370 371You can convert a certificate to DER form using the command: 372 373openssl x509 -in ca.pem -outform DER -out ca.der 374 375Occasionally someone suggests using a command such as: 376 377openssl pkcs12 -export -out cacert.p12 -in cacert.pem -inkey cakey.pem 378 379DO NOT DO THIS! This command will give away your CAs private key and 380reduces its security to zero: allowing anyone to forge certificates in 381whatever name they choose. 382 383* Why is OpenSSL x509 DN output not conformant to RFC2253? 384 385The ways to print out the oneline format of the DN (Distinguished Name) have 386been extended in version 0.9.7 of OpenSSL. Using the new X509_NAME_print_ex() 387interface, the "-nameopt" option could be introduded. See the manual 388page of the "openssl x509" commandline tool for details. The old behaviour 389has however been left as default for the sake of compatibility. 390 391* What is a "128 bit certificate"? Can I create one with OpenSSL? 392 393The term "128 bit certificate" is a highly misleading marketing term. It does 394*not* refer to the size of the public key in the certificate! A certificate 395containing a 128 bit RSA key would have negligible security. 396 397There were various other names such as "magic certificates", "SGC 398certificates", "step up certificates" etc. 399 400You can't generally create such a certificate using OpenSSL but there is no 401need to any more. Nowadays web browsers using unrestricted strong encryption 402are generally available. 403 404When there were tight export restrictions on the export of strong encryption 405software from the US only weak encryption algorithms could be freely exported 406(initially 40 bit and then 56 bit). It was widely recognised that this was 407inadequate. A relaxation the rules allowed the use of strong encryption but 408only to an authorised server. 409 410Two slighly different techniques were developed to support this, one used by 411Netscape was called "step up", the other used by MSIE was called "Server Gated 412Cryptography" (SGC). When a browser initially connected to a server it would 413check to see if the certificate contained certain extensions and was issued by 414an authorised authority. If these test succeeded it would reconnect using 415strong encryption. 416 417Only certain (initially one) certificate authorities could issue the 418certificates and they generally cost more than ordinary certificates. 419 420Although OpenSSL can create certificates containing the appropriate extensions 421the certificate would not come from a permitted authority and so would not 422be recognized. 423 424The export laws were later changed to allow almost unrestricted use of strong 425encryption so these certificates are now obsolete. 426 427 428[BUILD] ======================================================================= 429 430* Why does the linker complain about undefined symbols? 431 432Maybe the compilation was interrupted, and make doesn't notice that 433something is missing. Run "make clean; make". 434 435If you used ./Configure instead of ./config, make sure that you 436selected the right target. File formats may differ slightly between 437OS versions (for example sparcv8/sparcv9, or a.out/elf). 438 439In case you get errors about the following symbols, use the config 440option "no-asm", as described in INSTALL: 441 442 BF_cbc_encrypt, BF_decrypt, BF_encrypt, CAST_cbc_encrypt, 443 CAST_decrypt, CAST_encrypt, RC4, RC5_32_cbc_encrypt, RC5_32_decrypt, 444 RC5_32_encrypt, bn_add_words, bn_div_words, bn_mul_add_words, 445 bn_mul_comba4, bn_mul_comba8, bn_mul_words, bn_sqr_comba4, 446 bn_sqr_comba8, bn_sqr_words, bn_sub_words, des_decrypt3, 447 des_ede3_cbc_encrypt, des_encrypt, des_encrypt2, des_encrypt3, 448 des_ncbc_encrypt, md5_block_asm_host_order, sha1_block_asm_data_order 449 450If none of these helps, you may want to try using the current snapshot. 451If the problem persists, please submit a bug report. 452 453 454* Why does the OpenSSL test fail with "bc: command not found"? 455 456You didn't install "bc", the Unix calculator. If you want to run the 457tests, get GNU bc from ftp://ftp.gnu.org or from your OS distributor. 458 459 460* Why does the OpenSSL test fail with "bc: 1 no implemented"? 461 462On some SCO installations or versions, bc has a bug that gets triggered 463when you run the test suite (using "make test"). The message returned is 464"bc: 1 not implemented". 465 466The best way to deal with this is to find another implementation of bc 467and compile/install it. GNU bc (see http://www.gnu.org/software/software.html 468for download instructions) can be safely used, for example. 469 470 471* Why does the OpenSSL test fail with "bc: stack empty"? 472 473On some DG/ux versions, bc seems to have a too small stack for calculations 474that the OpenSSL bntest throws at it. This gets triggered when you run the 475test suite (using "make test"). The message returned is "bc: stack empty". 476 477The best way to deal with this is to find another implementation of bc 478and compile/install it. GNU bc (see http://www.gnu.org/software/software.html 479for download instructions) can be safely used, for example. 480 481 482* Why does the OpenSSL compilation fail on Alpha Tru64 Unix? 483 484On some Alpha installations running Tru64 Unix and Compaq C, the compilation 485of crypto/sha/sha_dgst.c fails with the message 'Fatal: Insufficient virtual 486memory to continue compilation.' As far as the tests have shown, this may be 487a compiler bug. What happens is that it eats up a lot of resident memory 488to build something, probably a table. The problem is clearly in the 489optimization code, because if one eliminates optimization completely (-O0), 490the compilation goes through (and the compiler consumes about 2MB of resident 491memory instead of 240MB or whatever one's limit is currently). 492 493There are three options to solve this problem: 494 4951. set your current data segment size soft limit higher. Experience shows 496that about 241000 kbytes seems to be enough on an AlphaServer DS10. You do 497this with the command 'ulimit -Sd nnnnnn', where 'nnnnnn' is the number of 498kbytes to set the limit to. 499 5002. If you have a hard limit that is lower than what you need and you can't 501get it changed, you can compile all of OpenSSL with -O0 as optimization 502level. This is however not a very nice thing to do for those who expect to 503get the best result from OpenSSL. A bit more complicated solution is the 504following: 505 506----- snip:start ----- 507 make DIRS=crypto SDIRS=sha "`grep '^CFLAG=' Makefile.ssl | \ 508 sed -e 's/ -O[0-9] / -O0 /'`" 509 rm `ls crypto/*.o crypto/sha/*.o | grep -v 'sha_dgst\.o'` 510 make 511----- snip:end ----- 512 513This will only compile sha_dgst.c with -O0, the rest with the optimization 514level chosen by the configuration process. When the above is done, do the 515test and installation and you're set. 516 5173. Reconfigure the toolkit with no-sha0 option to leave out SHA0. It 518should not be used and is not used in SSL/TLS nor any other recognized 519protocol in either case. 520 521 522* Why does the OpenSSL compilation fail with "ar: command not found"? 523 524Getting this message is quite usual on Solaris 2, because Sun has hidden 525away 'ar' and other development commands in directories that aren't in 526$PATH by default. One of those directories is '/usr/ccs/bin'. The 527quickest way to fix this is to do the following (it assumes you use sh 528or any sh-compatible shell): 529 530----- snip:start ----- 531 PATH=${PATH}:/usr/ccs/bin; export PATH 532----- snip:end ----- 533 534and then redo the compilation. What you should really do is make sure 535'/usr/ccs/bin' is permanently in your $PATH, for example through your 536'.profile' (again, assuming you use a sh-compatible shell). 537 538 539* Why does the OpenSSL compilation fail on Win32 with VC++? 540 541Sometimes, you may get reports from VC++ command line (cl) that it 542can't find standard include files like stdio.h and other weirdnesses. 543One possible cause is that the environment isn't correctly set up. 544To solve that problem for VC++ versions up to 6, one should run 545VCVARS32.BAT which is found in the 'bin' subdirectory of the VC++ 546installation directory (somewhere under 'Program Files'). For VC++ 547version 7 (and up?), which is also called VS.NET, the file is called 548VSVARS32.BAT instead. 549This needs to be done prior to running NMAKE, and the changes are only 550valid for the current DOS session. 551 552 553* What is special about OpenSSL on Redhat? 554 555Red Hat Linux (release 7.0 and later) include a preinstalled limited 556version of OpenSSL. For patent reasons, support for IDEA, RC5 and MDC2 557is disabled in this version. The same may apply to other Linux distributions. 558Users may therefore wish to install more or all of the features left out. 559 560To do this you MUST ensure that you do not overwrite the openssl that is in 561/usr/bin on your Red Hat machine. Several packages depend on this file, 562including sendmail and ssh. /usr/local/bin is a good alternative choice. The 563libraries that come with Red Hat 7.0 onwards have different names and so are 564not affected. (eg For Red Hat 7.2 they are /lib/libssl.so.0.9.6b and 565/lib/libcrypto.so.0.9.6b with symlinks /lib/libssl.so.2 and 566/lib/libcrypto.so.2 respectively). 567 568Please note that we have been advised by Red Hat attempting to recompile the 569openssl rpm with all the cryptography enabled will not work. All other 570packages depend on the original Red Hat supplied openssl package. It is also 571worth noting that due to the way Red Hat supplies its packages, updates to 572openssl on each distribution never change the package version, only the 573build number. For example, on Red Hat 7.1, the latest openssl package has 574version number 0.9.6 and build number 9 even though it contains all the 575relevant updates in packages up to and including 0.9.6b. 576 577A possible way around this is to persuade Red Hat to produce a non-US 578version of Red Hat Linux. 579 580FYI: Patent numbers and expiry dates of US patents: 581MDC-2: 4,908,861 13/03/2007 582IDEA: 5,214,703 25/05/2010 583RC5: 5,724,428 03/03/2015 584 585 586* Why does the OpenSSL compilation fail on MacOS X? 587 588If the failure happens when trying to build the "openssl" binary, with 589a large number of undefined symbols, it's very probable that you have 590OpenSSL 0.9.6b delivered with the operating system (you can find out by 591running '/usr/bin/openssl version') and that you were trying to build 592OpenSSL 0.9.7 or newer. The problem is that the loader ('ld') in 593MacOS X has a misfeature that's quite difficult to go around. 594Look in the file PROBLEMS for a more detailed explanation and for possible 595solutions. 596 597 598* Why does the OpenSSL test suite fail on MacOS X? 599 600If the failure happens when running 'make test' and the RC4 test fails, 601it's very probable that you have OpenSSL 0.9.6b delivered with the 602operating system (you can find out by running '/usr/bin/openssl version') 603and that you were trying to build OpenSSL 0.9.6d. The problem is that 604the loader ('ld') in MacOS X has a misfeature that's quite difficult to 605go around and has linked the programs "openssl" and the test programs 606with /usr/lib/libcrypto.dylib and /usr/lib/libssl.dylib instead of the 607libraries you just built. 608Look in the file PROBLEMS for a more detailed explanation and for possible 609solutions. 610 611* Why does the OpenSSL test suite fail in BN_sqr test [on a 64-bit platform]? 612 613Failure in BN_sqr test is most likely caused by a failure to configure the 614toolkit for current platform or lack of support for the platform in question. 615Run './config -t' and './apps/openssl version -p'. Do these platform 616identifiers match? If they don't, then you most likely failed to run 617./config and you're hereby advised to do so before filing a bug report. 618If ./config itself fails to run, then it's most likely problem with your 619local environment and you should turn to your system administrator (or 620similar). If identifiers match (and/or no alternative identifier is 621suggested by ./config script), then the platform is unsupported. There might 622or might not be a workaround. Most notably on SPARC64 platforms with GNU 623C compiler you should be able to produce a working build by running 624'./config -m32'. I understand that -m32 might not be what you want/need, 625but the build should be operational. For further details turn to 626<openssl-dev@openssl.org>. 627 628* Why does OpenBSD-i386 build fail on des-586.s with "Unimplemented segment type"? 629 630As of 0.9.7 assembler routines were overhauled for position independence 631of the machine code, which is essential for shared library support. For 632some reason OpenBSD is equipped with an out-of-date GNU assembler which 633finds the new code offensive. To work around the problem, configure with 634no-asm (and sacrifice a great deal of performance) or patch your assembler 635according to <URL: http://www.openssl.org/~appro/gas-1.92.3.OpenBSD.patch>. 636For your convenience a pre-compiled replacement binary is provided at 637<URL: http://www.openssl.org/~appro/gas-1.92.3.static.aout.bin>. 638Reportedly elder *BSD a.out platforms also suffer from this problem and 639remedy should be same. Provided binary is statically linked and should be 640working across wider range of *BSD branches, not just OpenBSD. 641 642* Why does the OpenSSL test suite fail in sha512t on x86 CPU? 643 644If the test program in question fails withs SIGILL, Illegal Instruction 645exception, then you more than likely to run SSE2-capable CPU, such as 646Intel P4, under control of kernel which does not support SSE2 647instruction extentions. See accompanying INSTALL file and 648OPENSSL_ia32cap(3) documentation page for further information. 649 650* Why does compiler fail to compile sha512.c? 651 652OpenSSL SHA-512 implementation depends on compiler support for 64-bit 653integer type. Few elder compilers [ULTRIX cc, SCO compiler to mention a 654couple] lack support for this and therefore are incapable of compiling 655the module in question. The recommendation is to disable SHA-512 by 656adding no-sha512 to ./config [or ./Configure] command line. Another 657possible alternative might be to switch to GCC. 658 659* Test suite still fails, what to do? 660 661Another common reason for failure to complete some particular test is 662simply bad code generated by a buggy component in toolchain or deficiency 663in run-time environment. There are few cases documented in PROBLEMS file, 664consult it for possible workaround before you beat the drum. Even if you 665don't find solution or even mention there, do reserve for possibility of 666a compiler bug. Compiler bugs might appear in rather bizarre ways, they 667never make sense, and tend to emerge when you least expect them. In order 668to identify one, drop optimization level, e.g. by editing CFLAG line in 669top-level Makefile, recompile and re-run the test. 670 671[PROG] ======================================================================== 672 673* Is OpenSSL thread-safe? 674 675Yes (with limitations: an SSL connection may not concurrently be used 676by multiple threads). On Windows and many Unix systems, OpenSSL 677automatically uses the multi-threaded versions of the standard 678libraries. If your platform is not one of these, consult the INSTALL 679file. 680 681Multi-threaded applications must provide two callback functions to 682OpenSSL by calling CRYPTO_set_locking_callback() and 683CRYPTO_set_id_callback(). This is described in the threads(3) 684manpage. 685 686* I've compiled a program under Windows and it crashes: why? 687 688This is usually because you've missed the comment in INSTALL.W32. 689Your application must link against the same version of the Win32 690C-Runtime against which your openssl libraries were linked. The 691default version for OpenSSL is /MD - "Multithreaded DLL". 692 693If you are using Microsoft Visual C++'s IDE (Visual Studio), in 694many cases, your new project most likely defaulted to "Debug 695Singlethreaded" - /ML. This is NOT interchangeable with /MD and your 696program will crash, typically on the first BIO related read or write 697operation. 698 699For each of the six possible link stage configurations within Win32, 700your application must link against the same by which OpenSSL was 701built. If you are using MS Visual C++ (Studio) this can be changed 702by: 703 704 1. Select Settings... from the Project Menu. 705 2. Select the C/C++ Tab. 706 3. Select "Code Generation from the "Category" drop down list box 707 4. Select the Appropriate library (see table below) from the "Use 708 run-time library" drop down list box. Perform this step for both 709 your debug and release versions of your application (look at the 710 top left of the settings panel to change between the two) 711 712 Single Threaded /ML - MS VC++ often defaults to 713 this for the release 714 version of a new project. 715 Debug Single Threaded /MLd - MS VC++ often defaults to 716 this for the debug version 717 of a new project. 718 Multithreaded /MT 719 Debug Multithreaded /MTd 720 Multithreaded DLL /MD - OpenSSL defaults to this. 721 Debug Multithreaded DLL /MDd 722 723Note that debug and release libraries are NOT interchangeable. If you 724built OpenSSL with /MD your application must use /MD and cannot use /MDd. 725 726As per 0.9.8 the above limitation is eliminated for .DLLs. OpenSSL 727.DLLs compiled with some specific run-time option [we insist on the 728default /MD] can be deployed with application compiled with different 729option or even different compiler. But there is a catch! Instead of 730re-compiling OpenSSL toolkit, as you would have to with prior versions, 731you have to compile small C snippet with compiler and/or options of 732your choice. The snippet gets installed as 733<install-root>/include/openssl/applink.c and should be either added to 734your application project or simply #include-d in one [and only one] 735of your application source files. Failure to link this shim module 736into your application manifests itself as fatal "no OPENSSL_Applink" 737run-time error. An explicit reminder is due that in this situation 738[mixing compiler options] it is as important to add CRYPTO_malloc_init 739prior first call to OpenSSL. 740 741* How do I read or write a DER encoded buffer using the ASN1 functions? 742 743You have two options. You can either use a memory BIO in conjunction 744with the i2d_*_bio() or d2i_*_bio() functions or you can use the 745i2d_*(), d2i_*() functions directly. Since these are often the 746cause of grief here are some code fragments using PKCS7 as an example: 747 748 unsigned char *buf, *p; 749 int len; 750 751 len = i2d_PKCS7(p7, NULL); 752 buf = OPENSSL_malloc(len); /* or Malloc, error checking omitted */ 753 p = buf; 754 i2d_PKCS7(p7, &p); 755 756At this point buf contains the len bytes of the DER encoding of 757p7. 758 759The opposite assumes we already have len bytes in buf: 760 761 unsigned char *p; 762 p = buf; 763 p7 = d2i_PKCS7(NULL, &p, len); 764 765At this point p7 contains a valid PKCS7 structure of NULL if an error 766occurred. If an error occurred ERR_print_errors(bio) should give more 767information. 768 769The reason for the temporary variable 'p' is that the ASN1 functions 770increment the passed pointer so it is ready to read or write the next 771structure. This is often a cause of problems: without the temporary 772variable the buffer pointer is changed to point just after the data 773that has been read or written. This may well be uninitialized data 774and attempts to free the buffer will have unpredictable results 775because it no longer points to the same address. 776 777 778* OpenSSL uses DER but I need BER format: does OpenSSL support BER? 779 780The short answer is yes, because DER is a special case of BER and OpenSSL 781ASN1 decoders can process BER. 782 783The longer answer is that ASN1 structures can be encoded in a number of 784different ways. One set of ways is the Basic Encoding Rules (BER) with various 785permissible encodings. A restriction of BER is the Distinguished Encoding 786Rules (DER): these uniquely specify how a given structure is encoded. 787 788Therefore, because DER is a special case of BER, DER is an acceptable encoding 789for BER. 790 791 792* I've tried using <M_some_evil_pkcs12_macro> and I get errors why? 793 794This usually happens when you try compiling something using the PKCS#12 795macros with a C++ compiler. There is hardly ever any need to use the 796PKCS#12 macros in a program, it is much easier to parse and create 797PKCS#12 files using the PKCS12_parse() and PKCS12_create() functions 798documented in doc/openssl.txt and with examples in demos/pkcs12. The 799'pkcs12' application has to use the macros because it prints out 800debugging information. 801 802 803* I've called <some function> and it fails, why? 804 805Before submitting a report or asking in one of the mailing lists, you 806should try to determine the cause. In particular, you should call 807ERR_print_errors() or ERR_print_errors_fp() after the failed call 808and see if the message helps. Note that the problem may occur earlier 809than you think -- you should check for errors after every call where 810it is possible, otherwise the actual problem may be hidden because 811some OpenSSL functions clear the error state. 812 813 814* I just get a load of numbers for the error output, what do they mean? 815 816The actual format is described in the ERR_print_errors() manual page. 817You should call the function ERR_load_crypto_strings() before hand and 818the message will be output in text form. If you can't do this (for example 819it is a pre-compiled binary) you can use the errstr utility on the error 820code itself (the hex digits after the second colon). 821 822 823* Why do I get errors about unknown algorithms? 824 825This can happen under several circumstances such as reading in an 826encrypted private key or attempting to decrypt a PKCS#12 file. The cause 827is forgetting to load OpenSSL's table of algorithms with 828OpenSSL_add_all_algorithms(). See the manual page for more information. 829 830 831* Why can't the OpenSSH configure script detect OpenSSL? 832 833Several reasons for problems with the automatic detection exist. 834OpenSSH requires at least version 0.9.5a of the OpenSSL libraries. 835Sometimes the distribution has installed an older version in the system 836locations that is detected instead of a new one installed. The OpenSSL 837library might have been compiled for another CPU or another mode (32/64 bits). 838Permissions might be wrong. 839 840The general answer is to check the config.log file generated when running 841the OpenSSH configure script. It should contain the detailed information 842on why the OpenSSL library was not detected or considered incompatible. 843 844 845* Can I use OpenSSL's SSL library with non-blocking I/O? 846 847Yes; make sure to read the SSL_get_error(3) manual page! 848 849A pitfall to avoid: Don't assume that SSL_read() will just read from 850the underlying transport or that SSL_write() will just write to it -- 851it is also possible that SSL_write() cannot do any useful work until 852there is data to read, or that SSL_read() cannot do anything until it 853is possible to send data. One reason for this is that the peer may 854request a new TLS/SSL handshake at any time during the protocol, 855requiring a bi-directional message exchange; both SSL_read() and 856SSL_write() will try to continue any pending handshake. 857 858 859* Why doesn't my server application receive a client certificate? 860 861Due to the TLS protocol definition, a client will only send a certificate, 862if explicitly asked by the server. Use the SSL_VERIFY_PEER flag of the 863SSL_CTX_set_verify() function to enable the use of client certificates. 864 865 866* Why does compilation fail due to an undefined symbol NID_uniqueIdentifier? 867 868For OpenSSL 0.9.7 the OID table was extended and corrected. In earlier 869versions, uniqueIdentifier was incorrectly used for X.509 certificates. 870The correct name according to RFC2256 (LDAP) is x500UniqueIdentifier. 871Change your code to use the new name when compiling against OpenSSL 0.9.7. 872 873 874* I think I've detected a memory leak, is this a bug? 875 876In most cases the cause of an apparent memory leak is an OpenSSL internal table 877that is allocated when an application starts up. Since such tables do not grow 878in size over time they are harmless. 879 880These internal tables can be freed up when an application closes using various 881functions. Currently these include following: 882 883Thread-local cleanup functions: 884 885 ERR_remove_state() 886 887Application-global cleanup functions that are aware of usage (and therefore 888thread-safe): 889 890 ENGINE_cleanup() and CONF_modules_unload() 891 892"Brutal" (thread-unsafe) Application-global cleanup functions: 893 894 ERR_free_strings(), EVP_cleanup() and CRYPTO_cleanup_all_ex_data(). 895 896 897=============================================================================== 898 899