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

protocol carkeyni2(I,R)
{
	role I
	{
		fresh ni: Nonce;

		send_1(I,R, {R,ni}sk(I) );
		send_2(I,R, {R,ni}sk(I) );
	}	
	
	role R
	{
		var ni: Nonce;

		recv_1(I,R, {R,ni}sk(I) );
		recv_2(I,R, {R,ni}sk(I) );
		claim_4(R,Nisynch);
	}
}