US Patent 7986780 Privacy-preserving substring creation

A system to contribute to creating a substring of a string may include a communication unit and a processing unit. The communication unit may be configured to receive an encrypted representation of a second share of the string. The string may be identical to the second share of the string combined with a first share of the string. The communication unit may be configured to send a rearranged representation of the encrypted representation of the second share of the string to a further system. The processing unit may be configured to rearrange a representation of the encrypted representation of the second share of the string using a first share of a start value of the substring. The start value may be identical to the first share of the start value added to a second share of the start value.