// See constructions/common/keygen_tools.go
func MaskEncoding(rs *common.RandomSource, surface common.Surface) func(int, int) encoding.Nibble {
return func(position, subPosition int) encoding.Nibble {
label := make([]byte, 16)
label[0], label[1], label[2], label[3], label[4] = 'M', 'E', byte(position), byte(subPosition), byte(surface)
return rs.Shuffle(label)
}
}
// See constructions/common/keygen_tools.go
func XOREncoding(rs *common.RandomSource, round int, surface common.Surface) func(int, int) encoding.Nibble {
return func(position, gate int) encoding.Nibble {
label := make([]byte, 16)
label[0], label[1], label[2], label[3], label[4] = 'X', byte(round), byte(position), byte(gate), byte(surface)
return rs.Shuffle(label)
}
}
// See constructions/common/keygen_tools.go
func RoundEncoding(rs *common.RandomSource, round int, surface common.Surface, shift func(int) int) func(int) encoding.Nibble {
return func(position int) encoding.Nibble {
position = 2*shift(position/2) + position%2
label := make([]byte, 16)
label[0], label[1], label[2], label[3] = 'R', byte(round), byte(position), byte(surface)
return rs.Shuffle(label)
}
}
// Encodes the output of a MB^(-1) Table / the input of an XOR Table.
//
// position: Position in the state array, counted in *bytes*.
// subPosition: Position in the MB^(-1) Table's ouptput for this byte, counted in nibbles.
func MBInverseEncoding(rs *common.RandomSource, round, position, subPosition int) encoding.Nibble {
label := make([]byte, 16)
label[0], label[1], label[2], label[3], label[4] = 'M', 'I', byte(round), byte(position), byte(subPosition)
return rs.Shuffle(label)
}