From 2e5308c675d5d4c007de0a40e100c4e7977d7ccb Mon Sep 17 00:00:00 2001
From: Michael Schlottke-Lakemper <michael@sloede.com>
Date: Sat, 20 Jan 2024 08:22:13 +0100
Subject: [PATCH] Support scalar operations for addition and subtraction

---
 src/arithmetic.jl  |  4 ++++
 src/openfhe.jl     | 29 +++++++++++++++++++++++++++++
 src/unencrypted.jl | 17 +++++++++++++++++
 test/test_unit.jl  |  4 ++++
 4 files changed, 54 insertions(+)

diff --git a/src/arithmetic.jl b/src/arithmetic.jl
index 10d757e..2bb78a5 100644
--- a/src/arithmetic.jl
+++ b/src/arithmetic.jl
@@ -2,11 +2,15 @@
 Base.:+(sv1::SecureVector, sv2::SecureVector) = add(sv1, sv2)
 Base.:+(sv::SecureVector, pv::PlainVector) = add(sv, pv)
 Base.:+(pv::PlainVector, sv::SecureVector) = add(sv, pv)
+Base.:+(sv::SecureVector, scalar::Real) = add(sv, scalar)
+Base.:+(scalar::Real, sv::SecureVector) = add(sv, scalar)
 
 # Subtract
 Base.:-(sv1::SecureVector, sv2::SecureVector) = subtract(sv1, sv2)
 Base.:-(sv::SecureVector, pv::PlainVector) = subtract(sv, pv)
 Base.:-(pv::PlainVector, sv::SecureVector) = subtract(pv, sv)
+Base.:-(sv::SecureVector, scalar::Real) = subtract(sv, scalar)
+Base.:-(scalar::Real, sv::SecureVector) = subtract(scalar, sv)
 
 # Negate
 Base.:-(sv::SecureVector) = negate(sv)
diff --git a/src/openfhe.jl b/src/openfhe.jl
index a328033..690b00a 100644
--- a/src/openfhe.jl
+++ b/src/openfhe.jl
@@ -93,6 +93,11 @@ function bootstrap!(secure_vector::SecureVector{<:OpenFHEBackend})
     secure_vector
 end
 
+
+############################################################################################
+# Arithmetic operations
+############################################################################################
+
 function add(sv1::SecureVector{<:OpenFHEBackend}, sv2::SecureVector{<:OpenFHEBackend})
     cc = get_crypto_context(sv1)
     ciphertext = OpenFHE.EvalAdd(cc, sv1.ciphertext, sv2.ciphertext)
@@ -109,6 +114,14 @@ function add(sv::SecureVector{<:OpenFHEBackend}, pv::PlainVector{<:OpenFHEBacken
     secure_vector
 end
 
+function add(sv::SecureVector{<:OpenFHEBackend}, scalar::Real)
+    cc = get_crypto_context(sv)
+    ciphertext = OpenFHE.EvalAdd(cc, sv.ciphertext, scalar)
+    secure_vector = SecureVector(ciphertext, sv.context)
+
+    secure_vector
+end
+
 function subtract(sv1::SecureVector{<:OpenFHEBackend}, sv2::SecureVector{<:OpenFHEBackend})
     cc = get_crypto_context(sv1)
     ciphertext = OpenFHE.EvalSub(cc, sv1.ciphertext, sv2.ciphertext)
@@ -133,6 +146,22 @@ function subtract(pv::PlainVector{<:OpenFHEBackend}, sv::SecureVector{<:OpenFHEB
     secure_vector
 end
 
+function subtract(sv::SecureVector{<:OpenFHEBackend}, scalar::Real)
+    cc = get_crypto_context(sv)
+    ciphertext = OpenFHE.EvalSub(cc, sv.ciphertext, scalar)
+    secure_vector = SecureVector(ciphertext, sv.context)
+
+    secure_vector
+end
+
+function subtract(scalar::Real, sv::SecureVector{<:OpenFHEBackend})
+    cc = get_crypto_context(sv)
+    ciphertext = OpenFHE.EvalSub(cc, scalar, sv.ciphertext)
+    secure_vector = SecureVector(ciphertext, sv.context)
+
+    secure_vector
+end
+
 function negate(sv::SecureVector{<:OpenFHEBackend})
     cc = get_crypto_context(sv)
     ciphertext = OpenFHE.EvalNegate(cc, sv.ciphertext)
diff --git a/src/unencrypted.jl b/src/unencrypted.jl
index 9b39d78..7b15470 100644
--- a/src/unencrypted.jl
+++ b/src/unencrypted.jl
@@ -35,6 +35,11 @@ end
 
 bootstrap!(secure_vector::SecureVector{<:Unencrypted}) = secure_vector
 
+
+############################################################################################
+# Arithmetic operations
+############################################################################################
+
 function add(sv1::SecureVector{<:Unencrypted}, sv2::SecureVector{<:Unencrypted})
     SecureVector(sv1.ciphertext .+ sv2.ciphertext, sv1.context)
 end
@@ -43,6 +48,10 @@ function add(sv::SecureVector{<:Unencrypted}, pv::PlainVector{<:Unencrypted})
     SecureVector(sv.ciphertext .+ pv.plaintext, sv.context)
 end
 
+function add(sv::SecureVector{<:Unencrypted}, scalar::Real)
+    SecureVector(sv.ciphertext .+ scalar, sv.context)
+end
+
 function subtract(sv1::SecureVector{<:Unencrypted}, sv2::SecureVector{<:Unencrypted})
     SecureVector(sv1.ciphertext .- sv2.ciphertext, sv1.context)
 end
@@ -55,6 +64,14 @@ function subtract(pv::PlainVector{<:Unencrypted}, sv::SecureVector{<:Unencrypted
     SecureVector(pv.plaintext .- sv.ciphertext, sv.context)
 end
 
+function subtract(sv::SecureVector{<:Unencrypted}, scalar::Real)
+    SecureVector(sv.ciphertext .- scalar, sv.context)
+end
+
+function subtract(scalar::Real, sv::SecureVector{<:Unencrypted})
+    SecureVector(scalar .- sv.ciphertext, sv.context)
+end
+
 function negate(sv::SecureVector{<:Unencrypted})
     SecureVector(-sv.ciphertext, sv.context)
 end
diff --git a/test/test_unit.jl b/test/test_unit.jl
index d843cf0..b4be383 100644
--- a/test/test_unit.jl
+++ b/test/test_unit.jl
@@ -64,12 +64,16 @@ for backend in ((; name = "OpenFHE", BackendT = OpenFHEBackend, context = contex
             @test sv1 + sv2 isa SecureVector
             @test sv1 + pv1 isa SecureVector
             @test pv1 + sv1 isa SecureVector
+            @test sv1 + 3 isa SecureVector
+            @test 4 + sv1 isa SecureVector
         end
 
         @testset verbose=true showtiming=true "subtract" begin
             @test sv1 - sv2 isa SecureVector
             @test sv1 - pv1 isa SecureVector
             @test pv1 - sv1 isa SecureVector
+            @test sv1 - 3 isa SecureVector
+            @test 4 - sv1 isa SecureVector
         end
 
         @testset verbose=true showtiming=true "multiply" begin