  In this paper, the sum secure degrees of freedom (SDoF) of the $K$-user
Multiple Input/Single Output (MISO) Broadcast Channel with Confidential
Messages (BCCM) and alternating Channel State Information at the Transmitter
(CSIT) is investigated. In the MISO BCCM, a $K$-antenna transmitter (TX)
communicates toward $K$ single-antenna receivers (RXs), so that message for RX
$k$ is kept secret from RX $j$ with $j<k$. For this model, we consider the
scenario in which the CSI of the RXs from $2$ to $K$ is instantaneously known
at the transmitter while CSI of RX $1$ is known at the transmitter (i)
instantaneously for half of the time and (ii) with a unit delay for the
remainder of the time. We refer to this CSIT availability as \emph{alternating}
CSIT. Alternating CIST has been shown to provide synergistic gains in terms of
SDoF and is thus of a viable strategy to ensure secure communication by simply
relying on the CSI feedback strategy. Our main contribution is the
characterization of sum SDoF for this model as $SDoF_{\rm sum}= (2K-1)/2$.
Interestingly, this $SDoF_{\rm sum}$ is attained by a rather simple
achievability in which the TX uses artificial noise to prevent the decoding of
the message of the unintended receivers at RX $1$. For simplicity first, the
proof for the case $K=3$ is discussed in detail and after that, we have
presented the results for any number of RXs.
