A computer-implemented method for sharing information about a subject without disclosing identification information about the subject includes comparing, by a first computer system, a third set of data with a fourth set of data. The third set of data is converted by a transformation from a first set of identification data of a first subject provided by the first computer system. The fourth set of data is converted by the transformation from a second set of identification data of a second subject provided by a second computer system. The transformation renders the first subject unidentifiable from the third set of data and the second subject unidentifiable from the fourth set of data. The computer-implemented method also includes transmitting, from the first computer system to the second computer, a fifth set of data when the third set of data corresponds to the fourth set of data.