Systems and techniques for authenticating joint friends of users of wireless devices. An authenticating authority delivers a token to a wireless device for each party identified as a friend of a user of the wireless device, such as through relationships in an online social network. Two wireless devices can use information relating to the tokens to determine information relating to joint friends of the users of the devices, such as the identities of joint friends or simply the numbers of joint friends. Tokens can be further refined to allow for analysis that provides information relating to the degree of intimacy of the relationship between a user and a party identified as a friend.