OpenSSL - Frequently Asked Questions -------------------------------------- * Which is the current version of OpenSSL? * Where is the documentation? * How can I contact the OpenSSL developers? * 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? * Which is the current version of OpenSSL? The current version is available from . OpenSSL 0.9.5 was released on February 28th, 2000. In addition to the current stable release, you can also access daily snapshots of the OpenSSL development version at , or get it by anonymous CVS access. * Where is the documentation? OpenSSL is a library that provides cryptographic functionality to applications such as secure web servers. Be sure to read the documentation of the application you want to use. The INSTALL file explains how to install this library. OpenSSL includes a command line utility that can be used to perform a variety of cryptographic functions. It is described in the openssl(1) manpage. Documentation for developers is currently being written. A few manual pages already are available; overviews over libcrypto and libssl are given in the crypto(3) and ssl(3) manpages. The OpenSSL manpages are installed in /usr/local/ssl/man/ (or a different directory if you specified one as described in INSTALL). In addition, you can read the most current versions at . For information on parts of libcrypto that are not yet documented, you might want to read Ariel Glenn's documentation on SSLeay 0.9, OpenSSL's predecessor, at . 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 resources help, but please note that it reflects the obsolete version SSLeay 0.6.6. * How can I contact the OpenSSL developers? The README file describes how to submit bug reports and patches to OpenSSL. Information on the OpenSSL mailing lists is available from . * Do I need patent licenses to use OpenSSL? The patents section of the README file lists patents that may apply to you if you want to use OpenSSL. For information on intellectual property rights, please consult a lawyer. The OpenSSL team does not offer legal advice. You can configure OpenSSL so as not to use RC5 and IDEA by using ./config no-rc5 no-idea Until the RSA patent expires, U.S. users may want to use ./config no-rc5 no-idea no-rsa Please note that you will *not* be able to communicate with most of the popular web browsers without RSA support. * Is OpenSSL thread-safe? Yes (with limitations: an SSL connection may not concurrently be used by multiple threads). On Windows and many Unix systems, OpenSSL automatically uses the multi-threaded versions of the standard libraries. If your platform is not one of these, consult the INSTALL file. Multi-threaded applications must provide two callback functions to OpenSSL. This is described in the threads(3) manpage. * Why do I get a "PRNG not seeded" error message? Cryptographic software needs a source of unpredictable data to work correctly. Many open source operating systems provide a "randomness device" that serves this purpose. On other systems, applications have to call the RAND_add() or RAND_seed() function with appropriate data before generating keys or performing public key encryption. Some broken applications do not do this. As of version 0.9.5, the OpenSSL functions that need randomness report an error if the random number generator has not been seeded with at least 128 bits of randomness. If this error occurs, 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. 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. * 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.