Assume there is a Trusted Third Party $($TTP$),$ a client C$,$ and a server S$.$

Setup.

TTP will be LU$2,$ Server will be LU$22,$ and the client will be LU$4$

$1)$ Create a public$/$private key pair for the TTP$.$

$2)$ Import public key of TTP for C$.$

$3)$ Create public$/$private key pair for S$.$

$4)$ Have TTP sign the public key for S$.$

C now wants to connect to S$.$

Handshake

$5)$ C $$downloads$$ signed public key of S

$6)$ Verify the public key$$s signature is correct.

$7)$ C encrypts $$Hello$$ using S$$s public key

$8)$ S decrypts the message and sends back a list of supported symmetric$-$key algorithms $($e$.$g$.$

AES$-128-$CBC$,$ etc.$)$ and hash functions $($e$.$g$.$ MD$5,$ SHA$1,$ etc.$)$

You can pick the list of algorithms

$9)$ C selects one of the symmetric$-$key algorithms and one of the hash functions, generates a

symmetric key, and sends that symmetric key and selected algorithms, encrypted under S$$s

public key. If needed, make sure you are also send the IV $($Initialization Vector$).$

You can decide on the format, whether it$$s space$-$separated or comma$-$separated or lineseparated. You can assume both C and S know the format.

$10)$ C encrypts $$Ready$$ using the symmetric key and creates a hash $($for integrity$).$

$11)$ C sends both the encrypted message and hash to S$.$

$12)$ S verifies integrity of message and decrypts the message.

$13)$ S encrypts $$Ready $2!$ using the symmetric key and creates a hash.

$14)$ S sends both the encrypted message and hash to C$.$

$15)$ C verifies integrity of message and decrypts the message.

Can you show the step by step commands for each part when working in the command prompt.

HINT:

$-$Public key encryption use gpg

~gpg $--$full$-$generate$-$key

~gpg $--$import

~gpg $--$export

~gpg $--$sign

~gpg $--$encrypt $--$recipient $"..."$ message.txt

~gpg $--$list$-$public$-$keys

$-$Symmetric key encryption $-$ use openssl

~openssl enc $-$ALGO $-$e $-$in input.txt $-$out output.enc $-$K KEY $-$iv IV

~openssl enc $-$ALGO $-$d $-$in output.enc $-$out input.txt $-$K KEY $-$iv IV

~openssl dgst $-$ALGO output.enc $>$ output.hash