A method performed by a mobile device at least partially under control of a positioning program, the method comprising: - establishing or initiating establishing a secure communication path to a remote device for receiving one or more signature parameter data sets (6041, 6042); - receiving said one or more signature parameter data sets (6041, 6042) via said secure communication path from said remote device; - estimating a position of said mobile device at least partially based on one or more radio signal parameters obtained by said mobile device, wherein position data representing said estimated position of said mobile device are obtained as a result of said estimating; - determining a digital signature of said position data at least partially based on at least one of said one or more signature parameter data sets (6041, 6042), wherein signature data representing said digital signature of said position data are obtained as a result of said determining; - providing said position data and said signature data to one or more application programs (605, 606) wherein said one or more application programs (605, 606) are at least two application programs (605, 606), and wherein, for each of said at least two application programs (605, 606), an individual signature parameter data set is obtained such that said one or more signature parameter data sets (6041, 6042) are at least two individual signature parameter data sets (6041, 6042), wherein, for each of said at least two application programs (605, 606), an individual digital signature is determined at least partially based on said respective individual signature parameter data set obtained for said respective application program of said at least two application programs (605, 606), wherein individual signature data are provided to each of said at least two application programs (605, 606) representing said individual digital signature determined for said respective one of said at least two application programs (605, 606). - establishing or initiating establishing a secure communication path to a remote device for receiving one or more signature parameter data sets (6041, 6042); - receiving said one or more signature parameter data sets (6041, 6042) via said secure communication path from said remote device; - estimating a position of said mobile device at least partially based on one or more radio signal parameters obtained by said mobile device, wherein position data representing said estimated position of said mobile device are obtained as a result of said estimating; - determining a digital signature of said position data at least partially based on at least one of said one or more signature parameter data sets (6041, 6042), wherein signature data representing said digital signature of said position data are obtained as a result of said determining; - providing said position data and said signature data to one or more application programs (605, 606) wherein said one or more application programs (605, 606) are at least two application programs (605, 606), and wherein, for each of said at least two application programs (605, 606), an individual signature parameter data set is obtained such that said one or more signature parameter data sets (6041, 6042) are at least two individual signature parameter data sets (6041, 6042), wherein, for each of said at least two application programs (605, 606), an individual digital signature is determined at least partially based on said respective individual signature parameter data set obtained for said respective application program of said at least two application programs (605, 606), wherein individual signature data are provided to each of said at least two application programs (605, 606) representing said individual digital signature determined for said respective one of said at least two application programs (605, 606). said one or more application programs (605, 606) are at least two application programs (605, 606), and wherein, for each of said at least two application programs (605, 606), an individual signature parameter data set is obtained such that said one or more signature parameter data sets (6041, 6042) are at least two individual signature parameter data sets (6041, 6042), wherein, for each of said at least two application programs (605, 606), an individual digital signature is determined at least partially based on said respective individual signature parameter data set obtained for said respective application program of said at least two application programs (605, 606), wherein individual signature data are provided to each of said at least two application programs (605, 606) representing said individual digital signature determined for said respective one of said at least two application programs (605, 606).