FAQ revision 127128
170856SjhbOpenSSL - Frequently Asked Questions 270856Sjhb-------------------------------------- 370856Sjhb 470856Sjhb[MISC] Miscellaneous questions 570856Sjhb 670856Sjhb* Which is the current version of OpenSSL? 770856Sjhb* Where is the documentation? 870856Sjhb* How can I contact the OpenSSL developers? 970856Sjhb* Where can I get a compiled version of OpenSSL? 1070856Sjhb* Why aren't tools like 'autoconf' and 'libtool' used? 1170856Sjhb* What is an 'engine' version? 1270856Sjhb* How do I check the authenticity of the OpenSSL distribution? 1370856Sjhb 1470856Sjhb[LEGAL] Legal questions 1570856Sjhb 1670856Sjhb* Do I need patent licenses to use OpenSSL? 1770856Sjhb* Can I use OpenSSL with GPL software? 1870856Sjhb 1970856Sjhb[USER] Questions on using the OpenSSL applications 2070856Sjhb 2170856Sjhb* Why do I get a "PRNG not seeded" error message? 2270856Sjhb* Why do I get an "unable to write 'random state'" error message? 2370856Sjhb* How do I create certificates or certificate requests? 2470856Sjhb* Why can't I create certificate requests? 2570856Sjhb* Why does <SSL program> fail with a certificate verify error? 2670856Sjhb* Why can I only use weak ciphers when I connect to a server using OpenSSL? 2770856Sjhb* How can I create DSA certificates? 2870856Sjhb* Why can't I make an SSL connection using a DSA certificate? 2970856Sjhb* How can I remove the passphrase on a private key? 30100280Sgordon* Why can't I use OpenSSL certificates with SSL client authentication? 31153430Siedowse* Why does my browser give a warning about a mismatched hostname? 32136224Smtm* How do I install a CA certificate into a browser? 33100280Sgordon* Why is OpenSSL x509 DN output not conformant to RFC2253? 34100280Sgordon 35100280Sgordon[BUILD] Questions about building and testing OpenSSL 36100280Sgordon 37156331Semax* Why does the linker complain about undefined symbols? 38156331Semax* Why does the OpenSSL test fail with "bc: command not found"? 39102993Sfenner* Why does the OpenSSL test fail with "bc: 1 no implemented"? 40102993Sfenner* Why does the OpenSSL test fail with "bc: stack empty"? 41165389Syar* Why does the OpenSSL compilation fail on Alpha Tru64 Unix? 42100280Sgordon* Why does the OpenSSL compilation fail with "ar: command not found"? 4370856Sjhb* Why does the OpenSSL compilation fail on Win32 with VC++? 4470856Sjhb* What is special about OpenSSL on Redhat? 4570856Sjhb* Why does the OpenSSL compilation fail on MacOS X? 4670856Sjhb* Why does the OpenSSL test suite fail on MacOS X? 4770856Sjhb* Why does the OpenSSL test suite fail in BN_sqr test [on a 64-bit platform]? 48270935Sse* Why does OpenBSD-i386 build fail on des-586.s with "Unimplemented segment type"? 49270935Sse 50179981Smtm[PROG] Questions about programming with OpenSSL 51270935Sse 52179981Smtm* Is OpenSSL thread-safe? 53179981Smtm* I've compiled a program under Windows and it crashes: why? 54179981Smtm* How do I read or write a DER encoded buffer using the ASN1 functions? 55270935Sse* I've tried using <M_some_evil_pkcs12_macro> and I get errors why? 56270935Sse* I've called <some function> and it fails, why? 57270935Sse* I just get a load of numbers for the error output, what do they mean? 58270935Sse* Why do I get errors about unknown algorithms? 59270935Sse* Why can't the OpenSSH configure script detect OpenSSL? 60270935Sse* Can I use OpenSSL's SSL library with non-blocking I/O? 61270935Sse* Why doesn't my server application receive a client certificate? 62270935Sse* Why does compilation fail due to an undefined symbol NID_uniqueIdentifier? 63179981Smtm 64179981Smtm=============================================================================== 65179981Smtm 66179981Smtm[MISC] ======================================================================== 67179981Smtm 68270935Sse* Which is the current version of OpenSSL? 69270935Sse 70270935SseThe current version is available from <URL: http://www.openssl.org>. 71270935SseOpenSSL 0.9.7d was released on March 17, 2004. 72270935Sse 73270935SseIn addition to the current stable release, you can also access daily 74270935Ssesnapshots of the OpenSSL development version at <URL: 75270935Sseftp://ftp.openssl.org/snapshot/>, or get it by anonymous CVS access. 76270935Sse 77270935Sse 78270935Sse* Where is the documentation? 79270935Sse 80270935SseOpenSSL is a library that provides cryptographic functionality to 81270935Sseapplications such as secure web servers. Be sure to read the 82270935Ssedocumentation of the application you want to use. The INSTALL file 83270935Sseexplains how to install this library. 84270935Sse 85270935SseOpenSSL includes a command line utility that can be used to perform a 86270935Ssevariety of cryptographic functions. It is described in the openssl(1) 87270935Ssemanpage. Documentation for developers is currently being written. A 88270935Ssefew manual pages already are available; overviews over libcrypto and 89270935Sselibssl are given in the crypto(3) and ssl(3) manpages. 90270935Sse 91270935SseThe OpenSSL manpages are installed in /usr/local/ssl/man/ (or a 92270935Ssedifferent directory if you specified one as described in INSTALL). 93270935SseIn addition, you can read the most current versions at 94270935Sse<URL: http://www.openssl.org/docs/>. 95270935Sse 96270935SseFor information on parts of libcrypto that are not yet documented, you 97270935Ssemight want to read Ariel Glenn's documentation on SSLeay 0.9, OpenSSL's 98270935Ssepredecessor, at <URL: http://www.columbia.edu/~ariel/ssleay/>. Much 99270935Sseof this still applies to OpenSSL. 100270935Sse 101270935SseThere is some documentation about certificate extensions and PKCS#12 102270935Ssein doc/openssl.txt 103270935Sse 104270935SseThe original SSLeay documentation is included in OpenSSL as 105270935Ssedoc/ssleay.txt. It may be useful when none of the other resources 106270935Ssehelp, but please note that it reflects the obsolete version SSLeay 107270935Sse0.6.6. 108270935Sse 109270935Sse 110270935Sse* How can I contact the OpenSSL developers? 111270935Sse 112270935SseThe README file describes how to submit bug reports and patches to 113270935SseOpenSSL. Information on the OpenSSL mailing lists is available from 114270935Sse<URL: http://www.openssl.org>. 115270935Sse 116270935Sse 117270935Sse* Where can I get a compiled version of OpenSSL? 118270935Sse 119270935SseYou can finder pointers to binary distributions in 120270935Ssehttp://www.openssl.org/related/binaries.html . 121270935Sse 122270935SseSome applications that use OpenSSL are distributed in binary form. 123270935SseWhen using such an application, you don't need to install OpenSSL 124270935Sseyourself; the application will include the required parts (e.g. DLLs). 125270935Sse 126270935SseIf you want to build OpenSSL on a Windows system and you don't have 127270935Ssea C compiler, read the "Mingw32" section of INSTALL.W32 for information 128270935Sseon how to obtain and install the free GNU C compiler. 129270935Sse 130270935SseA number of Linux and *BSD distributions include OpenSSL. 131270935Sse 132270935Sse 133270935Sse* Why aren't tools like 'autoconf' and 'libtool' used? 134270935Sse 135270935Sseautoconf will probably be used in future OpenSSL versions. If it was 136270935Sseless Unix-centric, it might have been used much earlier. 137270935Sse 138270935Sse* What is an 'engine' version? 139270935Sse 140270935SseWith version 0.9.6 OpenSSL was extended to interface to external crypto 141270935Ssehardware. This was realized in a special release '0.9.6-engine'. With 142270935Sseversion 0.9.7 (not yet released) the changes were merged into the main 143270935Ssedevelopment line, so that the special release is no longer necessary. 144270935Sse 145270935Sse* How do I check the authenticity of the OpenSSL distribution? 146270935Sse 147270935SseWe provide MD5 digests and ASC signatures of each tarball. 148270935SseUse MD5 to check that a tarball from a mirror site is identical: 149270935Sse 150270935Sse md5sum TARBALL | awk '{print $1;}' | cmp - TARBALL.md5 151270935Sse 152270935SseYou can check authenticity using pgp or gpg. You need the OpenSSL team 153270935Ssemember public key used to sign it (download it from a key server). Then 154270935Ssejust do: 155270935Sse 156270935Sse pgp TARBALL.asc 157270935Sse 158270935Sse[LEGAL] ======================================================================= 159270935Sse 160270935Sse* Do I need patent licenses to use OpenSSL? 161270935Sse 162270935SseThe patents section of the README file lists patents that may apply to 163270935Sseyou if you want to use OpenSSL. For information on intellectual 164156782Semaxproperty rights, please consult a lawyer. The OpenSSL team does not 165156782Semaxoffer legal advice. 166156331Semax 167102993SfennerYou can configure OpenSSL so as not to use RC5 and IDEA by using 168102993Sfenner ./config no-rc5 no-idea 169102993Sfenner 170271958Sse 171102993Sfenner* Can I use OpenSSL with GPL software? 172102993Sfenner 173179981SmtmOn many systems including the major Linux and BSD distributions, yes (the 174270935SseGPL does not place restrictions on using libraries that are part of the 175102993Sfennernormal operating system distribution). 176102993Sfenner 17770856SjhbOn other systems, the situation is less clear. Some GPL software copyright 178102993Sfennerholders claim that you infringe on their rights if you use OpenSSL with 179102993Sfennertheir software on operating systems that don't normally include OpenSSL. 180102993Sfenner 181102993SfennerIf you develop open source software that uses OpenSSL, you may find it 182102993Sfenneruseful to choose an other license than the GPL, or state explicitly that 183102993Sfenner"This program is released under the GPL with the additional exemption that 184179981Smtmcompiling, linking, and/or using OpenSSL is allowed." If you are using 185102993SfennerGPL software developed by others, you may want to ask the copyright holder 186102993Sfennerfor permission to use their software with OpenSSL. 187102993Sfenner 18870856Sjhb 189102993Sfenner[USER] ======================================================================== 190102993Sfenner 191102993Sfenner* Why do I get a "PRNG not seeded" error message? 192102993Sfenner 193102993SfennerCryptographic software needs a source of unpredictable data to work 194102993Sfennercorrectly. Many open source operating systems provide a "randomness 195179981Smtmdevice" (/dev/urandom or /dev/random) that serves this purpose. 196102993SfennerAll OpenSSL versions try to use /dev/urandom by default; starting with 197102993Sfennerversion 0.9.7, OpenSSL also tries /dev/random if /dev/urandom is not 198102993Sfenneravailable. 19970856Sjhb 200102993SfennerOn other systems, applications have to call the RAND_add() or 201102993SfennerRAND_seed() function with appropriate data before generating keys or 202102993Sfennerperforming public key encryption. (These functions initialize the 203102993Sfennerpseudo-random number generator, PRNG.) Some broken applications do 204102993Sfennernot do this. As of version 0.9.5, the OpenSSL functions that need 205102993Sfennerrandomness report an error if the random number generator has not been 206179981Smtmseeded with at least 128 bits of randomness. If this error occurs and 207102993Sfenneris not discussed in the documentation of the application you are 208227366Sjillesusing, please contact the author of that application; it is likely 209102993Sfennerthat it never worked correctly. OpenSSL 0.9.5 and later make the 210102993Sfennererror visible by refusing to perform potentially insecure encryption. 211102993Sfenner 212102993SfennerIf you are using Solaris 8, you can add /dev/urandom and /dev/random 213102993Sfennerdevices by installing patch 112438 (Sparc) or 112439 (x86), which are 214102993Sfenneravailable via the Patchfinder at <URL: http://sunsolve.sun.com> 21570856Sjhb(Solaris 9 includes these devices by default). For /dev/random support 216156782Semaxfor earlier Solaris versions, see Sun's statement at 217156782Semax<URL: http://sunsolve.sun.com/pub-cgi/retrieve.pl?doc=fsrdb/27606&zone_32=SUNWski> 218156782Semax(the SUNWski package is available in patch 105710). 219179981Smtm 220156782SemaxOn systems without /dev/urandom and /dev/random, it is a good idea to 221156782Semaxuse the Entropy Gathering Demon (EGD); see the RAND_egd() manpage for 222156782Semaxdetails. Starting with version 0.9.7, OpenSSL will automatically look 223156782Semaxfor an EGD socket at /var/run/egd-pool, /dev/egd-pool, /etc/egd-pool and 224156782Semax/etc/entropy. 225156782Semax 226156782SemaxMost components of the openssl command line utility automatically try 227156782Semaxto seed the random number generator from a file. The name of the 228156782Semaxdefault seeding file is determined as follows: If environment variable 229156782SemaxRANDFILE is set, then it names the seeding file. Otherwise if 230208060Sdougbenvironment variable HOME is set, then the seeding file is $HOME/.rnd. 231156782SemaxIf neither RANDFILE nor HOME is set, versions up to OpenSSL 0.9.6 will 232156782Semaxuse file .rnd in the current directory while OpenSSL 0.9.6a uses no 233156782Semaxdefault seeding file at all. OpenSSL 0.9.6b and later will behave 234156782Semaxsimilarly to 0.9.6a, but will use a default of "C:\" for HOME on 235156782SemaxWindows systems if the environment variable has not been set. 236156782Semax 237167889SbrooksIf the default seeding file does not exist or is too short, the "PRNG 238156782Semaxnot seeded" error message may occur. 239156782Semax 240156782SemaxThe openssl command line utility will write back a new state to the 241179981Smtmdefault seeding file (and create this file if necessary) unless 242156782Semaxthere was no sufficient seeding. 243179981Smtm 244179981SmtmPointing $RANDFILE to an Entropy Gathering Daemon socket does not work. 245179981SmtmUse the "-rand" option of the OpenSSL command line tools instead. 246179981SmtmThe $RANDFILE environment variable and $HOME/.rnd are only used by the 247179981SmtmOpenSSL command line tools. Applications using the OpenSSL library 248270935Sseprovide their own configuration options to specify the entropy source, 249179981Smtmplease check out the documentation coming the with application. 250179981Smtm 251156782Semax 252156782Semax* Why do I get an "unable to write 'random state'" error message? 253156782Semax 254156782Semax 255156782SemaxSometimes the openssl command line utility does not abort with 256156782Semaxa "PRNG not seeded" error message, but complains that it is 257156782Semax"unable to write 'random state'". This message refers to the 258156782Semaxdefault seeding file (see previous answer). A possible reason 259156782Semaxis that no default filename is known because neither RANDFILE 260156782Semaxnor HOME is set. (Versions up to 0.9.6 used file ".rnd" in the 261156782Semaxcurrent directory in this case, but this has changed with 0.9.6a.) 262156782Semax 263156782Semax 264156782Semax* How do I create certificates or certificate requests? 265156782Semax 266156782SemaxCheck out the CA.pl(1) manual page. This provides a simple wrapper round 267179981Smtmthe 'req', 'verify', 'ca' and 'pkcs12' utilities. For finer control check 268156782Semaxout the manual pages for the individual utilities and the certificate 269156782Semaxextensions documentation (currently in doc/openssl.txt). 270156782Semax 271156782Semax 272102993Sfenner* Why can't I create certificate requests? 273102993Sfenner 274102993SfennerYou typically get the error: 275102993Sfenner 276102993Sfenner unable to find 'distinguished_name' in config 277102993Sfenner problems making Certificate Request 278179981Smtm 279102993SfennerThis is because it can't find the configuration file. Check out the 280102993SfennerDIAGNOSTICS section of req(1) for more information. 281102993Sfenner 28270856Sjhb 283102993Sfenner* Why does <SSL program> fail with a certificate verify error? 284102993Sfenner 285102993SfennerThis problem is usually indicated by log messages saying something like 286102993Sfenner"unable to get local issuer certificate" or "self signed certificate". 287102993SfennerWhen a certificate is verified its root CA must be "trusted" by OpenSSL 288102993Sfennerthis typically means that the CA certificate must be placed in a directory 289179981Smtmor file and the relevant program configured to read it. The OpenSSL program 290102993Sfenner'verify' behaves in a similar way and issues similar error messages: check 291102993Sfennerthe verify(1) program manual page for more information. 292102993Sfenner 29370856Sjhb 294102993Sfenner* Why can I only use weak ciphers when I connect to a server using OpenSSL? 295102993Sfenner 296102993SfennerThis is almost certainly because you are using an old "export grade" browser 297102993Sfennerwhich only supports weak encryption. Upgrade your browser to support 128 bit 298102993Sfennerciphers. 299102993Sfenner 300179981Smtm 301102993Sfenner* How can I create DSA certificates? 302102993Sfenner 303102993SfennerCheck the CA.pl(1) manual page for a DSA certificate example. 30470856Sjhb 305102993Sfenner 306102993Sfenner* Why can't I make an SSL connection to a server using a DSA certificate? 307102993Sfenner 308102993SfennerTypically you'll see a message saying there are no shared ciphers when 309102993Sfennerthe same setup works fine with an RSA certificate. There are two possible 310102993Sfennercauses. The client may not support connections to DSA servers most web 311179981Smtmbrowsers (including Netscape and MSIE) only support connections to servers 312102993Sfennersupporting RSA cipher suites. The other cause is that a set of DH parameters 313102993Sfennerhas not been supplied to the server. DH parameters can be created with the 314102993Sfennerdhparam(1) command and loaded using the SSL_CTX_set_tmp_dh() for example: 31570856Sjhbcheck the source to s_server in apps/s_server.c for an example. 316102993Sfenner 317102993Sfenner 318102993Sfenner* How can I remove the passphrase on a private key? 319102993Sfenner 320102993SfennerFirstly you should be really *really* sure you want to do this. Leaving 321102993Sfennera private key unencrypted is a major security risk. If you decide that 322179981Smtmyou do have to do this check the EXAMPLES sections of the rsa(1) and 323102993Sfennerdsa(1) manual pages. 324102993Sfenner 325102993Sfenner 32670856Sjhb* Why can't I use OpenSSL certificates with SSL client authentication? 327102993Sfenner 328102993SfennerWhat will typically happen is that when a server requests authentication 329102993Sfennerit will either not include your certificate or tell you that you have 330102993Sfennerno client certificates (Netscape) or present you with an empty list box 331102993Sfenner(MSIE). The reason for this is that when a server requests a client 332102993Sfennercertificate it includes a list of CAs names which it will accept. Browsers 333179981Smtmwill only let you select certificates from the list on the grounds that 334102993Sfennerthere is little point presenting a certificate which the server will 335102993Sfennerreject. 336102993Sfenner 33770856SjhbThe solution is to add the relevant CA certificate to your servers "trusted 338102993SfennerCA list". How you do this depends on the server software in uses. You can 339102993Sfennerprint out the servers list of acceptable CAs using the OpenSSL s_client tool: 340102993Sfenner 341102993Sfenneropenssl s_client -connect www.some.host:443 -prexit 342102993Sfenner 343102993SfennerIf your server only requests certificates on certain URLs then you may need 344179981Smtmto manually issue an HTTP GET command to get the list when s_client connects: 345102993Sfenner 346167495SmuxGET /some/page/needing/a/certificate.html 347102993Sfenner 348102993SfennerIf your CA does not appear in the list then this confirms the problem. 349165683Syar 350102993Sfenner 351102993Sfenner* Why does my browser give a warning about a mismatched hostname? 35270856Sjhb 353102993SfennerBrowsers expect the server's hostname to match the value in the commonName 354102993Sfenner(CN) field of the certificate. If it does not then you get a warning. 355102993Sfenner 356179981Smtm 357102993Sfenner* How do I install a CA certificate into a browser? 358102993Sfenner 359102993SfennerThe usual way is to send the DER encoded certificate to the browser as 360102993SfennerMIME type application/x-x509-ca-cert, for example by clicking on an appropriate 361102993Sfennerlink. On MSIE certain extensions such as .der or .cacert may also work, or you 362100284Sdougbcan import the certificate using the certificate import wizard. 363179981Smtm 364270935SseYou can convert a certificate to DER form using the command: 365270935Sse 366270935Sseopenssl x509 -in ca.pem -outform DER -out ca.der 367270935Sse 368270935SseOccasionally someone suggests using a command such as: 369270935Sse 370102993Sfenneropenssl pkcs12 -export -out cacert.p12 -in cacert.pem -inkey cakey.pem 371103161Sgordon 372103161SgordonDO NOT DO THIS! This command will give away your CAs private key and 373156331Semaxreduces its security to zero: allowing anyone to forge certificates in 374156331Semaxwhatever name they choose. 375 376* Why is OpenSSL x509 DN output not conformant to RFC2253? 377 378The ways to print out the oneline format of the DN (Distinguished Name) have 379been extended in version 0.9.7 of OpenSSL. Using the new X509_NAME_print_ex() 380interface, the "-nameopt" option could be introduded. See the manual 381page of the "openssl x509" commandline tool for details. The old behaviour 382has however been left as default for the sake of compatibility. 383 384[BUILD] ======================================================================= 385 386* Why does the linker complain about undefined symbols? 387 388Maybe the compilation was interrupted, and make doesn't notice that 389something is missing. Run "make clean; make". 390 391If you used ./Configure instead of ./config, make sure that you 392selected the right target. File formats may differ slightly between 393OS versions (for example sparcv8/sparcv9, or a.out/elf). 394 395In case you get errors about the following symbols, use the config 396option "no-asm", as described in INSTALL: 397 398 BF_cbc_encrypt, BF_decrypt, BF_encrypt, CAST_cbc_encrypt, 399 CAST_decrypt, CAST_encrypt, RC4, RC5_32_cbc_encrypt, RC5_32_decrypt, 400 RC5_32_encrypt, bn_add_words, bn_div_words, bn_mul_add_words, 401 bn_mul_comba4, bn_mul_comba8, bn_mul_words, bn_sqr_comba4, 402 bn_sqr_comba8, bn_sqr_words, bn_sub_words, des_decrypt3, 403 des_ede3_cbc_encrypt, des_encrypt, des_encrypt2, des_encrypt3, 404 des_ncbc_encrypt, md5_block_asm_host_order, sha1_block_asm_data_order 405 406If none of these helps, you may want to try using the current snapshot. 407If the problem persists, please submit a bug report. 408 409 410* Why does the OpenSSL test fail with "bc: command not found"? 411 412You didn't install "bc", the Unix calculator. If you want to run the 413tests, get GNU bc from ftp://ftp.gnu.org or from your OS distributor. 414 415 416* Why does the OpenSSL test fail with "bc: 1 no implemented"? 417 418On some SCO installations or versions, bc has a bug that gets triggered 419when you run the test suite (using "make test"). The message returned is 420"bc: 1 not implemented". 421 422The best way to deal with this is to find another implementation of bc 423and compile/install it. GNU bc (see http://www.gnu.org/software/software.html 424for download instructions) can be safely used, for example. 425 426 427* Why does the OpenSSL test fail with "bc: stack empty"? 428 429On some DG/ux versions, bc seems to have a too small stack for calculations 430that the OpenSSL bntest throws at it. This gets triggered when you run the 431test suite (using "make test"). The message returned is "bc: stack empty". 432 433The best way to deal with this is to find another implementation of bc 434and compile/install it. GNU bc (see http://www.gnu.org/software/software.html 435for download instructions) can be safely used, for example. 436 437 438* Why does the OpenSSL compilation fail on Alpha Tru64 Unix? 439 440On some Alpha installations running Tru64 Unix and Compaq C, the compilation 441of crypto/sha/sha_dgst.c fails with the message 'Fatal: Insufficient virtual 442memory to continue compilation.' As far as the tests have shown, this may be 443a compiler bug. What happens is that it eats up a lot of resident memory 444to build something, probably a table. The problem is clearly in the 445optimization code, because if one eliminates optimization completely (-O0), 446the compilation goes through (and the compiler consumes about 2MB of resident 447memory instead of 240MB or whatever one's limit is currently). 448 449There are three options to solve this problem: 450 4511. set your current data segment size soft limit higher. Experience shows 452that about 241000 kbytes seems to be enough on an AlphaServer DS10. You do 453this with the command 'ulimit -Sd nnnnnn', where 'nnnnnn' is the number of 454kbytes to set the limit to. 455 4562. If you have a hard limit that is lower than what you need and you can't 457get it changed, you can compile all of OpenSSL with -O0 as optimization 458level. This is however not a very nice thing to do for those who expect to 459get the best result from OpenSSL. A bit more complicated solution is the 460following: 461 462----- snip:start ----- 463 make DIRS=crypto SDIRS=sha "`grep '^CFLAG=' Makefile.ssl | \ 464 sed -e 's/ -O[0-9] / -O0 /'`" 465 rm `ls crypto/*.o crypto/sha/*.o | grep -v 'sha_dgst\.o'` 466 make 467----- snip:end ----- 468 469This will only compile sha_dgst.c with -O0, the rest with the optimization 470level chosen by the configuration process. When the above is done, do the 471test and installation and you're set. 472 473 474* Why does the OpenSSL compilation fail with "ar: command not found"? 475 476Getting this message is quite usual on Solaris 2, because Sun has hidden 477away 'ar' and other development commands in directories that aren't in 478$PATH by default. One of those directories is '/usr/ccs/bin'. The 479quickest way to fix this is to do the following (it assumes you use sh 480or any sh-compatible shell): 481 482----- snip:start ----- 483 PATH=${PATH}:/usr/ccs/bin; export PATH 484----- snip:end ----- 485 486and then redo the compilation. What you should really do is make sure 487'/usr/ccs/bin' is permanently in your $PATH, for example through your 488'.profile' (again, assuming you use a sh-compatible shell). 489 490 491* Why does the OpenSSL compilation fail on Win32 with VC++? 492 493Sometimes, you may get reports from VC++ command line (cl) that it 494can't find standard include files like stdio.h and other weirdnesses. 495One possible cause is that the environment isn't correctly set up. 496To solve that problem for VC++ versions up to 6, one should run 497VCVARS32.BAT which is found in the 'bin' subdirectory of the VC++ 498installation directory (somewhere under 'Program Files'). For VC++ 499version 7 (and up?), which is also called VS.NET, the file is called 500VSVARS32.BAT instead. 501This needs to be done prior to running NMAKE, and the changes are only 502valid for the current DOS session. 503 504 505* What is special about OpenSSL on Redhat? 506 507Red Hat Linux (release 7.0 and later) include a preinstalled limited 508version of OpenSSL. For patent reasons, support for IDEA, RC5 and MDC2 509is disabled in this version. The same may apply to other Linux distributions. 510Users may therefore wish to install more or all of the features left out. 511 512To do this you MUST ensure that you do not overwrite the openssl that is in 513/usr/bin on your Red Hat machine. Several packages depend on this file, 514including sendmail and ssh. /usr/local/bin is a good alternative choice. The 515libraries that come with Red Hat 7.0 onwards have different names and so are 516not affected. (eg For Red Hat 7.2 they are /lib/libssl.so.0.9.6b and 517/lib/libcrypto.so.0.9.6b with symlinks /lib/libssl.so.2 and 518/lib/libcrypto.so.2 respectively). 519 520Please note that we have been advised by Red Hat attempting to recompile the 521openssl rpm with all the cryptography enabled will not work. All other 522packages depend on the original Red Hat supplied openssl package. It is also 523worth noting that due to the way Red Hat supplies its packages, updates to 524openssl on each distribution never change the package version, only the 525build number. For example, on Red Hat 7.1, the latest openssl package has 526version number 0.9.6 and build number 9 even though it contains all the 527relevant updates in packages up to and including 0.9.6b. 528 529A possible way around this is to persuade Red Hat to produce a non-US 530version of Red Hat Linux. 531 532FYI: Patent numbers and expiry dates of US patents: 533MDC-2: 4,908,861 13/03/2007 534IDEA: 5,214,703 25/05/2010 535RC5: 5,724,428 03/03/2015 536 537 538* Why does the OpenSSL compilation fail on MacOS X? 539 540If the failure happens when trying to build the "openssl" binary, with 541a large number of undefined symbols, it's very probable that you have 542OpenSSL 0.9.6b delivered with the operating system (you can find out by 543running '/usr/bin/openssl version') and that you were trying to build 544OpenSSL 0.9.7 or newer. The problem is that the loader ('ld') in 545MacOS X has a misfeature that's quite difficult to go around. 546Look in the file PROBLEMS for a more detailed explanation and for possible 547solutions. 548 549 550* Why does the OpenSSL test suite fail on MacOS X? 551 552If the failure happens when running 'make test' and the RC4 test fails, 553it's very probable that you have OpenSSL 0.9.6b delivered with the 554operating system (you can find out by running '/usr/bin/openssl version') 555and that you were trying to build OpenSSL 0.9.6d. The problem is that 556the loader ('ld') in MacOS X has a misfeature that's quite difficult to 557go around and has linked the programs "openssl" and the test programs 558with /usr/lib/libcrypto.dylib and /usr/lib/libssl.dylib instead of the 559libraries you just built. 560Look in the file PROBLEMS for a more detailed explanation and for possible 561solutions. 562 563* Why does the OpenSSL test suite fail in BN_sqr test [on a 64-bit platform]? 564 565Failure in BN_sqr test is most likely caused by a failure to configure the 566toolkit for current platform or lack of support for the platform in question. 567Run './config -t' and './apps/openssl version -p'. Do these platform 568identifiers match? If they don't, then you most likely failed to run 569./config and you're hereby advised to do so before filing a bug report. 570If ./config itself fails to run, then it's most likely problem with your 571local environment and you should turn to your system administrator (or 572similar). If identifiers match (and/or no alternative identifier is 573suggested by ./config script), then the platform is unsupported. There might 574or might not be a workaround. Most notably on SPARC64 platforms with GNU 575C compiler you should be able to produce a working build by running 576'./config -m32'. I understand that -m32 might not be what you want/need, 577but the build should be operational. For further details turn to 578<openssl-dev@openssl.org>. 579 580* Why does OpenBSD-i386 build fail on des-586.s with "Unimplemented segment type"? 581 582As of 0.9.7 assembler routines were overhauled for position independence 583of the machine code, which is essential for shared library support. For 584some reason OpenBSD is equipped with an out-of-date GNU assembler which 585finds the new code offensive. To work around the problem, configure with 586no-asm (and sacrifice a great deal of performance) or patch your assembler 587according to <URL: http://www.openssl.org/~appro/gas-1.92.3.OpenBSD.patch>. 588For your convenience a pre-compiled replacement binary is provided at 589<URL: http://www.openssl.org/~appro/gas-1.92.3.static.aout.bin>. 590Reportedly elder *BSD a.out platforms also suffer from this problem and 591remedy should be same. Provided binary is statically linked and should be 592working across wider range of *BSD branches, not just OpenBSD. 593 594[PROG] ======================================================================== 595 596* Is OpenSSL thread-safe? 597 598Yes (with limitations: an SSL connection may not concurrently be used 599by multiple threads). On Windows and many Unix systems, OpenSSL 600automatically uses the multi-threaded versions of the standard 601libraries. If your platform is not one of these, consult the INSTALL 602file. 603 604Multi-threaded applications must provide two callback functions to 605OpenSSL. This is described in the threads(3) manpage. 606 607 608* I've compiled a program under Windows and it crashes: why? 609 610This is usually because you've missed the comment in INSTALL.W32. 611Your application must link against the same version of the Win32 612C-Runtime against which your openssl libraries were linked. The 613default version for OpenSSL is /MD - "Multithreaded DLL". 614 615If you are using Microsoft Visual C++'s IDE (Visual Studio), in 616many cases, your new project most likely defaulted to "Debug 617Singlethreaded" - /ML. This is NOT interchangeable with /MD and your 618program will crash, typically on the first BIO related read or write 619operation. 620 621For each of the six possible link stage configurations within Win32, 622your application must link against the same by which OpenSSL was 623built. If you are using MS Visual C++ (Studio) this can be changed 624by: 625 6261. Select Settings... from the Project Menu. 6272. Select the C/C++ Tab. 6283. Select "Code Generation from the "Category" drop down list box 6294. Select the Appropriate library (see table below) from the "Use 630 run-time library" drop down list box. Perform this step for both 631 your debug and release versions of your application (look at the 632 top left of the settings panel to change between the two) 633 634 Single Threaded /ML - MS VC++ often defaults to 635 this for the release 636 version of a new project. 637 Debug Single Threaded /MLd - MS VC++ often defaults to 638 this for the debug version 639 of a new project. 640 Multithreaded /MT 641 Debug Multithreaded /MTd 642 Multithreaded DLL /MD - OpenSSL defaults to this. 643 Debug Multithreaded DLL /MDd 644 645Note that debug and release libraries are NOT interchangeable. If you 646built OpenSSL with /MD your application must use /MD and cannot use /MDd. 647 648 649* How do I read or write a DER encoded buffer using the ASN1 functions? 650 651You have two options. You can either use a memory BIO in conjunction 652with the i2d_XXX_bio() or d2i_XXX_bio() functions or you can use the 653i2d_XXX(), d2i_XXX() functions directly. Since these are often the 654cause of grief here are some code fragments using PKCS7 as an example: 655 656unsigned char *buf, *p; 657int len; 658 659len = i2d_PKCS7(p7, NULL); 660buf = OPENSSL_malloc(len); /* or Malloc, error checking omitted */ 661p = buf; 662i2d_PKCS7(p7, &p); 663 664At this point buf contains the len bytes of the DER encoding of 665p7. 666 667The opposite assumes we already have len bytes in buf: 668 669unsigned char *p; 670p = buf; 671p7 = d2i_PKCS7(NULL, &p, len); 672 673At this point p7 contains a valid PKCS7 structure of NULL if an error 674occurred. If an error occurred ERR_print_errors(bio) should give more 675information. 676 677The reason for the temporary variable 'p' is that the ASN1 functions 678increment the passed pointer so it is ready to read or write the next 679structure. This is often a cause of problems: without the temporary 680variable the buffer pointer is changed to point just after the data 681that has been read or written. This may well be uninitialized data 682and attempts to free the buffer will have unpredictable results 683because it no longer points to the same address. 684 685 686* I've tried using <M_some_evil_pkcs12_macro> and I get errors why? 687 688This usually happens when you try compiling something using the PKCS#12 689macros with a C++ compiler. There is hardly ever any need to use the 690PKCS#12 macros in a program, it is much easier to parse and create 691PKCS#12 files using the PKCS12_parse() and PKCS12_create() functions 692documented in doc/openssl.txt and with examples in demos/pkcs12. The 693'pkcs12' application has to use the macros because it prints out 694debugging information. 695 696 697* I've called <some function> and it fails, why? 698 699Before submitting a report or asking in one of the mailing lists, you 700should try to determine the cause. In particular, you should call 701ERR_print_errors() or ERR_print_errors_fp() after the failed call 702and see if the message helps. Note that the problem may occur earlier 703than you think -- you should check for errors after every call where 704it is possible, otherwise the actual problem may be hidden because 705some OpenSSL functions clear the error state. 706 707 708* I just get a load of numbers for the error output, what do they mean? 709 710The actual format is described in the ERR_print_errors() manual page. 711You should call the function ERR_load_crypto_strings() before hand and 712the message will be output in text form. If you can't do this (for example 713it is a pre-compiled binary) you can use the errstr utility on the error 714code itself (the hex digits after the second colon). 715 716 717* Why do I get errors about unknown algorithms? 718 719This can happen under several circumstances such as reading in an 720encrypted private key or attempting to decrypt a PKCS#12 file. The cause 721is forgetting to load OpenSSL's table of algorithms with 722OpenSSL_add_all_algorithms(). See the manual page for more information. 723 724 725* Why can't the OpenSSH configure script detect OpenSSL? 726 727Several reasons for problems with the automatic detection exist. 728OpenSSH requires at least version 0.9.5a of the OpenSSL libraries. 729Sometimes the distribution has installed an older version in the system 730locations that is detected instead of a new one installed. The OpenSSL 731library might have been compiled for another CPU or another mode (32/64 bits). 732Permissions might be wrong. 733 734The general answer is to check the config.log file generated when running 735the OpenSSH configure script. It should contain the detailed information 736on why the OpenSSL library was not detected or considered incompatible. 737 738 739* Can I use OpenSSL's SSL library with non-blocking I/O? 740 741Yes; make sure to read the SSL_get_error(3) manual page! 742 743A pitfall to avoid: Don't assume that SSL_read() will just read from 744the underlying transport or that SSL_write() will just write to it -- 745it is also possible that SSL_write() cannot do any useful work until 746there is data to read, or that SSL_read() cannot do anything until it 747is possible to send data. One reason for this is that the peer may 748request a new TLS/SSL handshake at any time during the protocol, 749requiring a bi-directional message exchange; both SSL_read() and 750SSL_write() will try to continue any pending handshake. 751 752 753* Why doesn't my server application receive a client certificate? 754 755Due to the TLS protocol definition, a client will only send a certificate, 756if explicitly asked by the server. Use the SSL_VERIFY_PEER flag of the 757SSL_CTX_set_verify() function to enable the use of client certificates. 758 759 760* Why does compilation fail due to an undefined symbol NID_uniqueIdentifier? 761 762For OpenSSL 0.9.7 the OID table was extended and corrected. In earlier 763versions, uniqueIdentifier was incorrectly used for X.509 certificates. 764The correct name according to RFC2256 (LDAP) is x500UniqueIdentifier. 765Change your code to use the new name when compiling against OpenSSL 0.9.7. 766 767 768=============================================================================== 769 770