A method, in a processing system comprising one or more processing units and one or more storage units , for generating secure alternative representation, wherein the method comprises: (S201) providing, by the processing system , a first sequence comprising a plurality of first values; (S203) providing, by the processing system , a plurality of storage cells belonging to a plurality of groups, each of the groups having one or more storage cells; (S205) performing, by the processing system , for each of the storage cells a symbol-deriving and cell-filling procedure, comprising: (S2051) deriving, by the processing system , one or more secret pointers, each of the one or more secret pointers pointing to one of the first values; (S2053) forming, by the processing system , a token by putting together one or more of the first values which are pointed by the one or more secret pointers; (S2055) mapping, by the processing system , the token into a symbol; and (S2057) filling, by the processing system , the symbol into the corresponding one of the storage cells; (S207) composing, by the processing system , a queue for each of the groups by picking up one or more symbols filled in the one or more storage cells of a corresponding one of the groups; and (S209) generating, by the processing system , a secure alternative representation for the first sequence by concatenating the composed queue for each of the groups. (S201) providing, by the processing system , a first sequence comprising a plurality of first values; (S203) providing, by the processing system , a plurality of storage cells belonging to a plurality of groups, each of the groups having one or more storage cells; (S205) performing, by the processing system , for each of the storage cells a symbol-deriving and cell-filling procedure, comprising: (S2051) deriving, by the processing system , one or more secret pointers, each of the one or more secret pointers pointing to one of the first values; (S2053) forming, by the processing system , a token by putting together one or more of the first values which are pointed by the one or more secret pointers; (S2055) mapping, by the processing system , the token into a symbol; and (S2057) filling, by the processing system , the symbol into the corresponding one of the storage cells; (S207) composing, by the processing system , a queue for each of the groups by picking up one or more symbols filled in the one or more storage cells of a corresponding one of the groups; and (S209) generating, by the processing system , a secure alternative representation for the first sequence by concatenating the composed queue for each of the groups. (S2051) deriving, by the processing system , one or more secret pointers, each of the one or more secret pointers pointing to one of the first values; (S2053) forming, by the processing system , a token by putting together one or more of the first values which are pointed by the one or more secret pointers; (S2055) mapping, by the processing system , the token into a symbol; and (S2057) filling, by the processing system , the symbol into the corresponding one of the storage cells; (S207) composing, by the processing system , a queue for each of the groups by picking up one or more symbols filled in the one or more storage cells of a corresponding one of the groups; and (S209) generating, by the processing system , a secure alternative representation for the first sequence by concatenating the composed queue for each of the groups. <EOS>