OpenSSL - Frequently Asked Questions
--------------------------------------
+* Which is the current version of OpenSSL?
* Where is the documentation?
* How can I contact the OpenSSL developers?
-* Do I have to license patents to use OpenSSL?
+* Do I need patent licenses to use OpenSSL?
* Is OpenSSL thread-safe?
* Why do I get a "PRNG not seeded" error message?
+* Why does the linker complain about undefined symbols?
+* Where can I get a compiled version of OpenSSL?
+* I've compiled a program under Windows and it crashes: 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?
+* 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?
+* How can I create DSA certificates?
+* Why can't I make an SSL connection using a DSA certificate?
+* Why can't the OpenSSH configure script detect OpenSSL?
+
+
+* Which is the current version of OpenSSL?
+
+The current version is available from <URL: http://www.openssl.org>.
+OpenSSL 0.9.5a was released on April 1st, 2000.
+
+In addition to the current stable release, you can also access daily
+snapshots of the OpenSSL development version at <URL:
+ftp://ftp.openssl.org/snapshot/>, or get it by anonymous CVS access.
* Where is the documentation?
predecessor, at <URL: http://www.columbia.edu/~ariel/ssleay/>. Much
of this still applies to OpenSSL.
+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 ressources
+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.
<URL: http://www.openssl.org>.
-* Do I have to license patents to use OpenSSL?
+* 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
* Is OpenSSL thread-safe?
-Yes. 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.
+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. This will be described in the threads(3) manpage. [That
-page has not been written yet. Please read the "threads.doc" section
-of doc/ssleay.txt instead.]
+OpenSSL. This is described in the threads(3) manpage.
* Why do I get a "PRNG not seeded" error message?
number generator has not been seeded with at least 128 bits of
randomness. If this error occurs, please contact the author of the
application you are using. It is likely that it never worked
-correctly. OpenSSL 0.9.5 makes the error visible by refusing to
-perform potentially insecure encryption.
+correctly. OpenSSL 0.9.5 and later make the error visible by refusing
+to perform potentially insecure encryption.
+
+On systems without /dev/urandom, it is a good idea to use the Entropy
+Gathering Demon; see the RAND_egd() manpage for details.
+
+Most components of the openssl command line tool try to use the
+file $HOME/.rnd (or $RANDFILE, if this environment variable is set)
+for seeding the PRNG. If this file does not exist or is too short,
+the "PRNG not seeded" error message may occur.
+
+[Note to OpenSSL 0.9.5 users: The command "openssl rsa" in version
+0.9.5 does not do this and will fail on systems without /dev/urandom
+when trying to password-encrypt an RSA key! This is a bug in the
+library; try a later version instead.]
+
+
+* 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.
+
+
+* Where can I get a compiled version of OpenSSL?
+
+Some applications that use OpenSSL are distributed in binary form.
+When using such an application, you don't need to install OpenSSL
+yourself; the application will include the required parts (e.g. DLLs).
+
+If you want to install OpenSSL on a Windows system and you don't have
+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.
+
+
+* I've compiled a program under Windows and it crashes: why?
+
+This is usually because you've missed the comment in INSTALL.W32. You
+must link with the multithreaded DLL version of the VC++ runtime library
+otherwise the conflict will cause a program to crash: typically on the
+first BIO related read or write operation.
+
+
+* 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?
+
+This can happen under several circumstances such as reading in an
+encrypted private key or attempting to decrypt a PKCS#12 file. The cause
+is forgetting to load OpenSSL's table of algorithms with
+OpenSSL_add_all_algorithms(). See the manual page for more information.
+
+
+* 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 (currently in doc/openssl.txt).
+
+
+* 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.
+
+
+* 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 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.
+
+
+* Why can't the OpenSSH configure script detect OpenSSL?
+
+There is a problem with OpenSSH 1.2.2p1, in that the configure script
+can't find the installed OpenSSL libraries. The problem is actually
+a small glitch that is easily solved with the following patch to be
+applied to the OpenSSH distribution:
+
+----- snip:start -----
+--- openssh-1.2.2p1/configure.in.orig Thu Mar 23 18:56:58 2000
++++ openssh-1.2.2p1/configure.in Thu Mar 23 18:55:05 2000
+@@ -152,10 +152,10 @@
+ AC_MSG_CHECKING([for OpenSSL/SSLeay directory])
+ for ssldir in "" $tryssldir /usr /usr/local/openssl /usr/lib/openssl /usr/local/ssl /usr/lib/ssl /usr/local /usr/pkg /opt /opt/openssl ; do
+ if test ! -z "$ssldir" ; then
+- LIBS="$saved_LIBS -L$ssldir"
++ LIBS="$saved_LIBS -L$ssldir/lib"
+ CFLAGS="$CFLAGS -I$ssldir/include"
+ if test "x$need_dash_r" = "x1" ; then
+- LIBS="$LIBS -R$ssldir"
++ LIBS="$LIBS -R$ssldir/lib"
+ fi
+ fi
+ LIBS="$LIBS -lcrypto"
+--- openssh-1.2.2p1/configure.orig Thu Mar 23 18:55:02 2000
++++ openssh-1.2.2p1/configure Thu Mar 23 18:57:08 2000
+@@ -1890,10 +1890,10 @@
+ echo "configure:1891: checking for OpenSSL/SSLeay directory" >&5
+ for ssldir in "" $tryssldir /usr /usr/local/openssl /usr/lib/openssl /usr/local/ssl /usr/lib/ssl /usr/local /usr/pkg /opt /opt/openssl ; do
+ if test ! -z "$ssldir" ; then
+- LIBS="$saved_LIBS -L$ssldir"
++ LIBS="$saved_LIBS -L$ssldir/lib"
+ CFLAGS="$CFLAGS -I$ssldir/include"
+ if test "x$need_dash_r" = "x1" ; then
+- LIBS="$LIBS -R$ssldir"
++ LIBS="$LIBS -R$ssldir/lib"
+ fi
+ fi
+ LIBS="$LIBS -lcrypto"
+----- snip:end -----
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