  In many communication channels, secrecy constraints usually incur a penalty
in capacity, as well as generalized degrees-of-freedom (GDoF). In this work we
show an interesting observation that, adding a helper can totally remove the
penalty in sum GDoF, for a two-user symmetric Gaussian interference channel.
For the interference channel where each transmitter sends a message to an
intended receiver without secrecy constraints, the sum GDoF is a well-known "W"
curve, characterized by Etkin-Tse-Wang in 2008. If the secrecy constraints are
imposed on this interference channel, where the message of each transmitter
must be secure from the unintended receiver (eavesdropper), then a GDoF penalty
is incurred and the secure sum GDoF is reduced to a modified "W" curve, derived
by Chen recently. In this work we show that, by adding a helper into this
interference channel with secrecy constraints, the secure sum GDoF turns out to
be a "W" curve, which is the same as the sum GDoF of the setting without
secrecy constraints. The proposed scheme is based on the cooperative jamming
and a careful signal design such that the jamming signal of the helper is
aligned at a specific direction and power level with the information signals of
the transmitters, which allows to totally remove the penalty in GDoF due to the
secrecy constraints. Furthermore, the estimation approaches of noise removal
and signal separation due to the rational independence are used in the secure
rate analysis.
