documentation is included in each OpenSSL distribution under the docs
directory.
-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 <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