Abstract: Methods for secure random selection of t client devices from a set of N client devices and methods for secure computation of inputs of t client devices randomly selected from N client devices are described. Such random selection method may include determining an initial binary vector b of weight t by setting the first t bits to one: bi=1, 1?i?t, and all further bits to zero: bi=0, t<i?N; each client device i (i=1, . . . , N) of the set of N client devices jointly generating a random binary vector b of weight t in an obfuscated domain on the basis of the initial binary vector b including: determining a position n in the binary vector; determining a random number r in {n, n+1, . . . N}; and, using the random number to swap binary values at positions n and r of the binary vector b.

Abstract: Methods for secure random selection of t client devices from a set of N client devices and methods for secure computation of inputs of t client devices randomly selected from N client devices are described. Such random selection method may include determining an initial binary vector b of weight t by setting the first t bits to one: bi=1, 1 ?i?t, and all further bits to zero: bi=0, t<i?N; each client device i (i=1, . . . , N) of the set of N client devices jointly generating a random binary vector b of weight t in an obfuscated domain on the basis of the initial binary vector b including: determining a position n in the binary vector; determining a random number r in {n,n+1, . . . N}; and, using the random number to swap binary values at positions n and r of the binary vector b.

Abstract: A privacy preserving computation protocol for data analytics is described.

Abstract: A method of issuing electronic vouchers (Vi) which a user (U) may submit to a merchant (M) in exchange for goods or services comprises the steps of: an issuer (I) receiving an electronic declaration (Di?1) from the user (U), the issuer verifying the electronic declaration (Di?1), and the issuer issuing a new electronic voucher (Vi) for use with the merchant (M) only if the electronic declaration comprises a signature (SM) of a merchant on a previous electronic voucher (Vi?1). The vouchers (Vi) and declarations (Di?1) are preferably blinded by the user such that the user remains anonymous. However, the electronic vouchers (Vi) may contain the identity (Q) of the user (U), which identity may be revealed when a voucher is submitted more than once.

Abstract: A method of issuing electronic vouchers (Vi) which a user (U) may submit to a merchant (M) in exchange for goods or services comprises the steps of: an issuer (I) receiving an electronic declaration (Di?1) from the user (U), the issuer verifying the electronic declaration (Di?1), and the issuer issuing a new electronic voucher (Vi) for use with the merchant (M) only if the electronic declaration comprises a signature (SM) of a merchant on a previous electronic voucher (Vi?1). The vouchers (Vi) and declarations (Di?1) are preferably blinded by the user such that the user remains anonymous. However, the electronic vouchers (Vi) may contain the identity (Q) of the user (U), which identity may be revealed when a voucher is submitted more than once.