Ciphertext-to-Plaintext Addition

D-2.5 Ciphertext-to-Plaintext Addition

BFV’s ciphertext-to-plaintext addition uses RLWE’s ciphertext-to-plaintext addition scheme with the sign of the $A \cdot S$ term flipped in the encryption and decryption formula. Specifically, this is equivalent to the alternative GLWE version’s (§B-4.4) ciphertext-to-plaintext addition scheme (§C-2) with $k = 1$ .

$⟨$ Summary D-2.5 $⟩$ BFV Ciphertext-to-Plaintext Addition

${𝖱𝖫𝖶𝖤}_{S, σ} (Δ M) + Δ Λ$

$= (A, B) + Δ Λ$

$= (A, B + Δ \cdot Λ)$

$= {𝖱𝖫𝖶𝖤}_{S, σ} (Δ (M + Λ))$

[prev][parent][next]