Public | Subsampling operator R _{ Ω } |
Unitary matrices U _{1} and U _{2} | |
Structure of a keystream generator | |
Secret | Initial seed (or state) k∈{0,1}^{L} of a keystream generator |
Keystream generation | With the initial seed k, a keystream s∈{−1,+1}^{N} is generated. The keystream s is renewed at each encryption. |
CS encryption | With the keystream s and a plaintext \(\mathbf {x} \in {\mathbb {R}}^{N}\), a ciphertext is generated by \(\mathbf {r} = \boldsymbol {\Phi } \mathbf {x} + \mathbf {n} \in {\mathbb {R}}^{M} \), where \(\boldsymbol {\Phi } = \frac {1}{\sqrt {MN}} \mathbf {R}_{\Omega } \mathbf {U}_{1} \text {diag} (\mathbf {s}) \mathbf {U}_{2}\) and n is a measurement noise. |
CS decryption | The plaintext x is reconstructed by a CS recovery algorithm with the knowledge of s. |