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Understanding a problem in Security services and protocols

I know my question is a homework problem and I don't want an answer, I just want to understand how this problem could be solved!
you can give a similar example or show me how to do part of the problem, I will be grateful.

Four Security services: confidentiality (C), Integrity (I), Sender Authentication (A), and Non-Repudiation (NR)

Not: assume that the public key (and its private key) cannot be forged and is authentic. So, if a signature of a message can be verified via the corresponding public key, the sender will not be able to deny having sent the message.

Suppose the following notations are used:
k_1  ,k_2:keys
S:sender
R:receiver
E_k (x):Encryptionof x under k
〖SIG〗_k (x):signature on x under k
X_pri:private key of entity X  
X_pub:public key of entity X  
H:a public secure cryptographic hash function such as SHA-1  
〖PRNG〗_s:a binary stream from a pesudo random number generator seeded with s
||:simple concatenation
M:the message
 
For each protocol use C, I, A and NR to represent the services protocol provides. If the protocol cannot provide any service wire “None”.

      
  1. S generates a random session key s_k  and sends〖 E〗_(S_pub ) ( s_k )||〖 E〗_(R_pub ) ( s_k )  || (M ⊕〖PRNG 〗_(s_k ) )to R.
  2.      〖 S send y=E〗_(k_1 ) ( x || H(k_(2 ) || x) )  to R.
  3.      S send y=〖〖 E〗_(R_pub ) (x ||  SIG〗_(S_pri ) (H(x))) to R.
  4.      S generates a new symmetric key s_k  and sends y= E_(S_pub ) ( s_k )||〖 E〗_(R_pub ) ( s_k )|| 〖SIG 〗_(S_pri ) (s_k )|| to 〖 E〗_(s_k ) (x)R.

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Thank you for the reply, really helpful.
No worries. Thanks.