Algorithm 1 SDC-net executed by user $u_k$.

Input: Users $u_i$ for $i=1,...,n$ with $i\ne k$, message $m_k$. Output: Message $m_{out}$, which is the sum of all the messages of the participants.  1: Establish shared random secrets $s_{k,i}$ for each user $u_i$, with $i\ne k$ and $s_{k,i}+s_{i,k}=0$.  2: Calculate $M_k=m_k+{\sum }_{j=1,j\ne k}^n{s}_{k,j}$.  3: Send $M_k$ to $u_i,\forall i\in \{1,...,n\}\setminus \left\{k\right\}$.  4: Receive $M_i$ from $u_i,\forall i\in \{1,...,n\}\setminus \left\{k\right\}$.  5: Calculate $m_{out}={\sum }_{j=1}^n{M}_i={\sum }_{j=1}^n{m}_i$.