A method for establishing a link between user identifiers of different systems without disclosing specific user identifying information, the method comprising: encrypting, by a first party system, one or more first data sets each comprising a match key and a user identifier associated with the first party system; sending, by the first party system, the encrypted one or more first data sets to a third party system; receiving, by the first party system from the third party system, one or more encrypted second data sets each comprising a match key and a user identifier associated with the third party system; receiving, by the first party system from the third party system, one or more double encrypted first data sets, the one or more double encrypted first data sets comprising the encrypted one or more first data sets further encrypted by the third party system; encrypting, by the first party system, the encrypted one or more second data sets received from the third party system to generate one or more double encrypted second data set; generating, by the first party system, a matching relationship based on the double encrypted one or more first data sets and the double encrypted one or more second data sets, the matching relationship indicating one or more links between the match keys associated with the first party system and the match keys associated with the third party system; pruning, by the first party system, the matching relationship by removing one or more of the links between the match keys by determining match keys of the third party system that have more than one link; and assigning, by the first party system, bridge identifiers for the user identifiers associated with the first party system and the user identifiers associated with the third party system based on the matching relationship, the bridge identifier being a link between the user identifiers associated with the first party system and the user identifiers associated with the third party system. encrypting, by a first party system, one or more first data sets each comprising a match key and a user identifier associated with the first party system; sending, by the first party system, the encrypted one or more first data sets to a third party system; receiving, by the first party system from the third party system, one or more encrypted second data sets each comprising a match key and a user identifier associated with the third party system; receiving, by the first party system from the third party system, one or more double encrypted first data sets, the one or more double encrypted first data sets comprising the encrypted one or more first data sets further encrypted by the third party system; encrypting, by the first party system, the encrypted one or more second data sets received from the third party system to generate one or more double encrypted second data set; generating, by the first party system, a matching relationship based on the double encrypted one or more first data sets and the double encrypted one or more second data sets, the matching relationship indicating one or more links between the match keys associated with the first party system and the match keys associated with the third party system; pruning, by the first party system, the matching relationship by removing one or more of the links between the match keys by determining match keys of the third party system that have more than one link; and assigning, by the first party system, bridge identifiers for the user identifiers associated with the first party system and the user identifiers associated with the third party system based on the matching relationship, the bridge identifier being a link between the user identifiers associated with the first party system and the user identifiers associated with the third party system.