Encryption is the conversion of data or messages into a form called cypertext so  other unauthorized people can't read it  and cannot easily understand . 
decryption is the process of  converting inverted data back into its orignal form so we can understand it
these both are very important in wireless communication.
2 3 2
Coding using R.S.A Algo:-
choose any two prime no.(2,5).  (p,q)
find module. M=p.q
find a=(p-1)*(q-1).
find key.   1<k<a
assign natural no. for alphabet.
raise these no. to the power of key.divide each no. by module.

no need to say thanks its ok...