const pk: Function;
secret sk: Function;
inversekeys (pk,sk);

protocol soph(I,R)
{
	role I
	{
		fresh ni: Nonce;

		send_1(I,R, {I,ni}pk(R) );
		read_2(R,I, ni );
		claim_3(I,Niagree);
	}	
	
	role R
	{
		var ni: Nonce;

		read_1(I,R, {I,ni}pk(R) );
		send_2(R,I, ni );
	}
}