Patent ID: 7673144

Claim:
A group signature device for providing a message (m) accompanied by a group signature (S), comprising: means for storing personalized data (z, Kz) identifying any one individual member (M) of a group (G), wherein said group signature device is associated to said one individual member (M) of the group (G); means for storing a predefined private signature key (SK) common to all members of the group (G); encryption means (B 3 ) for producing a single encrypted text (C), intended to be associated with said message (m), using said personalized data (z, Kz) of said one individual member (M) only; signing means (B 6 ) which enables said one individual member (M) to produce the group signature (S) on behalf of the group (G) using said stored predefined private signature key (SK) common to all group members, wherein only the message to be signed (m) and said single encrypted text (C) produced using the personalized data (z, Kz) of said one individual member (M) are used to produce said group signature (S); and means for outputting the message (m) and the group signature (S) to a checker, such that the checker, upon receiving the message accompanied by the group signature, is able to verify that the message (m) is associated with the group (U) based on the group signature (S), with the identity of the individual member (M) of the group (G) remaining anonymous to the checker.