Assignment for week 6: The goal is to study and use OpenSSL API on two tasks -
generate an RSA key pair and work with TLS certificate validation.

Deadline: November 24, 2020 (8:00 AM), maximum is 5+5 points.

Write two simple programs using OpenSSL library on Linux.

1) Create a simple program that generates 4096 bit RSA key
with public exponent 65537 and print private and public output
to the screen.

Hints:

 - Use RSA_generate_key_ex() function.

 - Use PEM_read/write_PrivateKey or BIO based PEM_read/write_bio_PrivateKey
   (the same for public key).

2) Create a program that will connect to https port (443) of faculty
web server (www.fi.muni.cz) and prints info about the whole certification
chain provided by server.

The info for www.fi.muni.cz must contain:
 - Issuer
 - Subject
 - "Not before" certificate validity date
 - "Not after" certificate date

Example output format (for google.com):
Cert 0
  Issuer: GTS CA 1O1
  Subject: www.google.com
  Not before: Oct 28 16:23:45 2020 GMT
  Not after: Jan 20 16:23:45 2021 GMT
Cert 1
  Issuer: GlobalSign
  Subject: GTS CA 1O1
  Not before: Jun 15 00:00:42 2017 GMT
  Not after: Dec 15 00:00:42 2021 GMT
Cert 2
  Issuer: GlobalSign
  Subject: GlobalSign
  Not before: Dec 15 08:00:00 2006 GMT
  Not after: Dec 15 08:00:00 2021 GMT

Hints:

 - You can modify 7_tls_client_openssl example (it already contains Issuer and Subject).

 - Print info about *all* (server and CA) certificates, not only the server one.

 - For validity dates use X509_get0_notBefore() and  X509_get0_notAfter() and
   ASN1 date helper function ASN1_TIME_print()


Your submitted archive should contain *two* C programs above and Makefiles.

The source code must be compilable on the provided virtual machine (Linux Fedora)
or on aisa server.