1 OpenSSL - Frequently Asked Questions
2 --------------------------------------
4 * Which is the current version of OpenSSL?
5 * Where is the documentation?
6 * How can I contact the OpenSSL developers?
7 * Do I need patent licenses to use OpenSSL?
8 * Is OpenSSL thread-safe?
9 * Why do I get a "PRNG not seeded" error message?
10 * Why does the linker complain about undefined symbols?
11 * Where can I get a compiled version of OpenSSL?
12 * I've compiled a program under Windows and it crashes: why?
13 * Why do I get errors about unknown algorithms?
14 * How do I create certificates or certificate requests?
15 * Why can't I create certificate requests?
16 * Why can't the OpenSSH configure script detect OpenSSL?
19 * Which is the current version of OpenSSL?
21 The current version is available from <URL: http://www.openssl.org>.
22 OpenSSL 0.9.5 was released on February 28th, 2000.
24 In addition to the current stable release, you can also access daily
25 snapshots of the OpenSSL development version at <URL:
26 ftp://ftp.openssl.org/snapshot/>, or get it by anonymous CVS access.
29 * Where is the documentation?
31 OpenSSL is a library that provides cryptographic functionality to
32 applications such as secure web servers. Be sure to read the
33 documentation of the application you want to use. The INSTALL file
34 explains how to install this library.
36 OpenSSL includes a command line utility that can be used to perform a
37 variety of cryptographic functions. It is described in the openssl(1)
38 manpage. Documentation for developers is currently being written. A
39 few manual pages already are available; overviews over libcrypto and
40 libssl are given in the crypto(3) and ssl(3) manpages.
42 The OpenSSL manpages are installed in /usr/local/ssl/man/ (or a
43 different directory if you specified one as described in INSTALL).
44 In addition, you can read the most current versions at
45 <URL: http://www.openssl.org/docs/>.
47 For information on parts of libcrypto that are not yet documented, you
48 might want to read Ariel Glenn's documentation on SSLeay 0.9, OpenSSL's
49 predecessor, at <URL: http://www.columbia.edu/~ariel/ssleay/>. Much
50 of this still applies to OpenSSL.
52 There is some documentation about certificate extensions and PKCS#12
55 The original SSLeay documentation is included in OpenSSL as
56 doc/ssleay.txt. It may be useful when none of the other resources
57 help, but please note that it reflects the obsolete version SSLeay
61 * How can I contact the OpenSSL developers?
63 The README file describes how to submit bug reports and patches to
64 OpenSSL. Information on the OpenSSL mailing lists is available from
65 <URL: http://www.openssl.org>.
68 * Do I need patent licenses to use OpenSSL?
70 The patents section of the README file lists patents that may apply to
71 you if you want to use OpenSSL. For information on intellectual
72 property rights, please consult a lawyer. The OpenSSL team does not
75 You can configure OpenSSL so as not to use RC5 and IDEA by using
76 ./config no-rc5 no-idea
78 Until the RSA patent expires, U.S. users may want to use
79 ./config no-rc5 no-idea no-rsa
81 Please note that you will *not* be able to communicate with most of
82 the popular web browsers without RSA support.
85 * Is OpenSSL thread-safe?
87 Yes (with limitations: an SSL connection may not concurrently be used
88 by multiple threads). On Windows and many Unix systems, OpenSSL
89 automatically uses the multi-threaded versions of the standard
90 libraries. If your platform is not one of these, consult the INSTALL
93 Multi-threaded applications must provide two callback functions to
94 OpenSSL. This is described in the threads(3) manpage.
97 * Why do I get a "PRNG not seeded" error message?
99 Cryptographic software needs a source of unpredictable data to work
100 correctly. Many open source operating systems provide a "randomness
101 device" that serves this purpose. On other systems, applications have
102 to call the RAND_add() or RAND_seed() function with appropriate data
103 before generating keys or performing public key encryption.
105 Some broken applications do not do this. As of version 0.9.5, the
106 OpenSSL functions that need randomness report an error if the random
107 number generator has not been seeded with at least 128 bits of
108 randomness. If this error occurs, please contact the author of the
109 application you are using. It is likely that it never worked
110 correctly. OpenSSL 0.9.5 makes the error visible by refusing to
111 perform potentially insecure encryption.
113 Most components of the openssl command line tool try to use the
114 file $HOME/.rnd (or $RANDFILE, if this environment variable is set)
115 for seeding the PRNG. If this file does not exist or is too short,
116 the "PRNG not seeded" error message may occur.
117 Note that the command "openssl rsa" in OpenSSL 0.9.5 does not do this
118 and will fail on systems without /dev/urandom when trying to
119 password-encrypt an RSA key! This is a bug in the library;
120 try a later snaphost instead.
123 * Why does the linker complain about undefined symbols?
125 Maybe the compilation was interrupted, and make doesn't notice that
126 something is missing. Run "make clean; make".
128 If you used ./Configure instead of ./config, make sure that you
129 selected the right target. File formats may differ slightly between
130 OS versions (for example sparcv8/sparcv9, or a.out/elf).
132 In case you get errors about the following symbols, use the config
133 option "no-asm", as described in INSTALL:
135 BF_cbc_encrypt, BF_decrypt, BF_encrypt, CAST_cbc_encrypt,
136 CAST_decrypt, CAST_encrypt, RC4, RC5_32_cbc_encrypt, RC5_32_decrypt,
137 RC5_32_encrypt, bn_add_words, bn_div_words, bn_mul_add_words,
138 bn_mul_comba4, bn_mul_comba8, bn_mul_words, bn_sqr_comba4,
139 bn_sqr_comba8, bn_sqr_words, bn_sub_words, des_decrypt3,
140 des_ede3_cbc_encrypt, des_encrypt, des_encrypt2, des_encrypt3,
141 des_ncbc_encrypt, md5_block_asm_host_order, sha1_block_asm_data_order
143 If none of these helps, you may want to try using the current snapshot.
144 If the problem persists, please submit a bug report.
147 * Where can I get a compiled version of OpenSSL?
149 Some applications that use OpenSSL are distributed in binary form.
150 When using such an application, you don't need to install OpenSSL
151 yourself; the application will include the required parts (e.g. DLLs).
153 If you want to install OpenSSL on a Windows system and you don't have
154 a C compiler, read the "Mingw32" section of INSTALL.W32 for information
155 on how to obtain and install the free GNU C compiler.
157 A number of Linux and *BSD distributions include OpenSSL.
159 * I've compiled a program under Windows and it crashes: why?
161 This is usually because you've missed the comment in INSTALL.W32. You
162 must link with the multithreaded DLL version of the VC++ runtime library
163 otherwise the conflict will cause a program to crash: typically on the
164 first BIO related read or write operation.
167 * Why do I get errors about unknown algorithms?
169 This can happen under several circumstances such as reading in an
170 encrypted private key or attempting to decrypt a PKCS#12 file. The cause
171 is forgetting to load OpenSSL's table of algorithms with
172 OpenSSL_add_all_algorithms(). See the manual page for more information.
175 * How do I create certificates or certificate requests?
177 Check out the CA.pl(1) manual page. This provides a simple wrapper round
178 the 'req', 'verify', 'ca' and 'pkcs12' utilities. For finer control check
179 out the manual pages for the individual utilities and the certificate
180 extensions documentation (currently in doc/openssl.txt).
183 * Why can't I create certificate requests?
185 You typically get the error:
187 unable to find 'distinguished_name' in config
188 problems making Certificate Request
190 This is because it can't find the configuration file. Check out the
191 DIAGNOSTICS section of req(1) for more information.
194 * Why can't the OpenSSH configure script detect OpenSSL?
196 There is a problem with OpenSSH 1.2.2p1, in that the configure script
197 can't find the installed OpenSSL libraries. The problem is actually
198 a small glitch that is easily solved with the following patch to be
199 applied to the OpenSSH distribution:
201 ----- snip:start -----
202 --- openssh-1.2.2p1/configure.in.orig Thu Mar 23 18:56:58 2000
203 +++ openssh-1.2.2p1/configure.in Thu Mar 23 18:55:05 2000
204 @@ -152,10 +152,10 @@
205 AC_MSG_CHECKING([for OpenSSL/SSLeay directory])
206 for ssldir in "" $tryssldir /usr /usr/local/openssl /usr/lib/openssl /usr/local/ssl /usr/lib/ssl /usr/local /usr/pkg /opt /opt/openssl ; do
207 if test ! -z "$ssldir" ; then
208 - LIBS="$saved_LIBS -L$ssldir"
209 + LIBS="$saved_LIBS -L$ssldir/lib"
210 CFLAGS="$CFLAGS -I$ssldir/include"
211 if test "x$need_dash_r" = "x1" ; then
212 - LIBS="$LIBS -R$ssldir"
213 + LIBS="$LIBS -R$ssldir/lib"
216 LIBS="$LIBS -lcrypto"
217 --- openssh-1.2.2p1/configure.orig Thu Mar 23 18:55:02 2000
218 +++ openssh-1.2.2p1/configure Thu Mar 23 18:57:08 2000
219 @@ -1890,10 +1890,10 @@
220 echo "configure:1891: checking for OpenSSL/SSLeay directory" >&5
221 for ssldir in "" $tryssldir /usr /usr/local/openssl /usr/lib/openssl /usr/local/ssl /usr/lib/ssl /usr/local /usr/pkg /opt /opt/openssl ; do
222 if test ! -z "$ssldir" ; then
223 - LIBS="$saved_LIBS -L$ssldir"
224 + LIBS="$saved_LIBS -L$ssldir/lib"
225 CFLAGS="$CFLAGS -I$ssldir/include"
226 if test "x$need_dash_r" = "x1" ; then
227 - LIBS="$LIBS -R$ssldir"
228 + LIBS="$LIBS -R$ssldir/lib"
231 LIBS="$LIBS -lcrypto"