Task 1

Generate an Edwards curve key and sign a file using the OpenSSL command line.

Later, during the seminar, you will do the same using C OpenSSL API.
Note that you had a similar task for the ASN1 seminar, and you can use the same commands here.

- Generate keys with Ed25519 scheme
  # openssl genpkey -algorithm Ed25519 -out private.pem

- Export public key
  # openssl pkey -in private.pem -pubout -out public.pem

- Sign a file. Note the signature size.
  # echo "message" > message.txt
  # openssl pkeyutl -sign -inkey private.pem -out sign.bin -rawin -in message.txt

- Verify signature
  # openssl pkeyutl -verify -pubin -inkey public.pem -rawin -in message.txt -sigfile sign.bin

- Print info about keys
  # openssl pkey -text -in private.pem
  # openssl pkey -pubin -text -in public.pem


Task 2

Investigate a certificate chain returned in TLS connection.

Later, during the seminar, you will do the same using C OpenSSL API.

Connect to some host (-connect option), note you will need to provide a servername (hostname) if there are multiple servers hosted on the same IP address.
The null redirection is to close the connection without actually sending anything.

 # openssl s_client -showcerts -servername www.google.com -connect www.google.com:443 </dev/null

Try to change the server name to some of your favorite servers.
Grab some certificate from the output, store to file, and print info:
 # openssl x509 -text -in <stored file>

Now connect again and simulate a real HTTPS download of the robots.txt file.
We will send a trivial GET command here:

 # echo -e "GET /robots.txt HTTP/1.1\r\nHost: www.google.com\r\nConnection: Close\r\n\r\n" | openssl s_client -quiet -connect www.google.com:443