openssl for DEBIAN
----------------------

openssl replaces ssleay.

The application links to openssl like req, ca, verify and s_client
have been removed.

Instead of `<application>` please call now `openssl <application>`

eg: 
instead of `req` please call `openssl req`

TLS protovol version and RSA key size
-------------------------------------
The default system global policy is to support TLSv1.2+ and security level two.
Please see
  https://www.openssl.org/docs/man1.1.1/man5/config.html
  https://www.openssl.org/docs/man1.1.1/man3/SSL_CTX_set_security_level.html#DEFAULT-CALLBACK-BEHAVIOUR
for configurations details of `MinProtocol' and `CipherString' in
/etc/ssl/openssl.cnf case you really require to support legacy systems.

PATENT ISSUES
-------------

Some algorithms used in the library are covered by patents.  As
a result, the following algorithms in libcrypto have been disabled:
- RC5
- MDC2
- IDEA

Also see the patents section in the README file.


Self-signed certs and webservers:
---------------------------------

If you get with a selfsigned certificate and a webserver:
 > "The certificate is not approved for the attempted operation."

Bodo_Moeller@public.uni-hamburg.de (Bodo Moeller) writes:
>Probably you are using a CA certificate for your server; if you use
>"openssl req" to generate a new key and self-signed certificate with
>the default openssl.cnf, the certificate you get includes certain
>X.509v3 extensions that make it unfit for use as a server certificate.
>This was not so with earlier versions of the software because back
>then there was far less X.509v3 support.
>
>To look at the certificate some HTTPS server presents to its cliens,
>use "openssl s_client -port 443 -host your.server", store the output
>(at least the part from "-----BEGIN CERTIFICATE-----" up to "-----END
>CERTIFICATE-----", including these separators) in a file and use
>"openssl x509 -in the_file_you_just_stored -text" to look at it in
>readable form.  If it has in the "X509v3 extensions section" any of
>the following entries, it is not usable as a server certificate:
>
>            X509v3 Basic Constraints:
>                CA:TRUE
>
>            X509v3 Key Usage:
>                Certificate Sign, CRL Sign
>
>To quickly create a new server key and certificate that works with
>Netscape, you can just copy the original openssl.cnf file and comment
>out the "x509_extensions" entry in the "[ req ]" section.
>The, use "openssl req ..." as before to create a new certificate and
>key.


Christoph Martin <martin@uni-mainz.de>, Wed, 31 Mar 1999 16:00:51 +0200