SEALCrypt

SEALCrypt is a C++ library that provides a simple, user-friendly interface for homomorphic encryption using Microsoft SEAL. It makes it easy to perform computations on encrypted data without ever decrypting it.

Features

• Simple API - Clean, intuitive interface that hides SEAL complexity
• Homomorphic Operations - Add, subtract, and multiply encrypted values using natural operators (+, -, *)
• File Encryption - Encrypt and decrypt files with homomorphic encryption
• Security Presets - Choose from Low, Medium, or High security levels

Prerequisites

• CMake (>= 3.12)
• C++17 compatible compiler
• Microsoft SEAL (>= 4.1)
• Git (for installation)

Installation

Building from Source

git clone https://github.com/arianizadi/SEALCrypt.git
cd SEALCrypt
mkdir build && cd build
cmake ..
make
sudo make install

Uninstalling

# From the build directory
sudo make uninstall

Quick Start

Homomorphic Addition Example

#include <sealcrypt/sealcrypt.hpp>
#include <iostream>

int main() {
    // Create context with medium security
    sealcrypt::CryptoContext ctx(sealcrypt::SecurityLevel::Medium);

    // Generate keys
    sealcrypt::KeyPair keys(ctx);
    keys.generate();

    // Encrypt two numbers
    auto a = sealcrypt::HomomorphicInt::encrypt(100, ctx, keys);
    auto b = sealcrypt::HomomorphicInt::encrypt(50, ctx, keys);

    // Add them while encrypted!
    auto sum = a + b;

    // Decrypt to see the result
    std::cout << "100 + 50 = " << sum.decrypt(ctx, keys) << std::endl;  // 150

    return 0;
}

File Encryption Example

#include <sealcrypt/sealcrypt.hpp>

int main() {
    sealcrypt::CryptoContext ctx;
    sealcrypt::KeyPair keys(ctx);
    keys.generate();
    keys.save("public.key", "private.key");

    // Encrypt a file
    sealcrypt::Encryptor encryptor(ctx);
    encryptor.encryptFile("secret.txt", "secret.enc", keys);

    // Decrypt a file
    sealcrypt::Decryptor decryptor(ctx);
    decryptor.decryptFile("secret.enc", "decrypted.txt", keys);

    return 0;
}

CLI Usage

# Generate keys
./sealcrypt generate-keys --public public.key --private private.key

# Encrypt a file
./sealcrypt encrypt --input secret.txt --output secret.enc --public-key public.key

# Decrypt a file
./sealcrypt decrypt --input secret.enc --output decrypted.txt --private-key private.key

API Reference

CryptoContext

The foundation for all encryption operations.

// Create with security preset
sealcrypt::CryptoContext ctx(sealcrypt::SecurityLevel::Medium);

// Or with custom parameters
sealcrypt::CryptoContext ctx(8192, 65537);

KeyPair

Manages public and secret keys.

sealcrypt::KeyPair keys(ctx);
keys.generate();                           // Generate new keys
keys.save("pub.key", "priv.key");         // Save to files
keys.load("pub.key", "priv.key");         // Load from files
keys.loadPublicKey("pub.key");            // Load only public key
keys.loadSecretKey("priv.key");           // Load only secret key

HomomorphicInt

Encrypted integers with arithmetic operators.

auto a = sealcrypt::HomomorphicInt::encrypt(100, ctx, keys);
auto b = sealcrypt::HomomorphicInt::encrypt(50, ctx, keys);

auto sum = a + b;           // Homomorphic addition
auto diff = a - b;          // Homomorphic subtraction
auto prod = a * b;          // Homomorphic multiplication
auto neg = -a;              // Negation

auto result = sum.addPlain(10, ctx);  // Add plaintext (more efficient)
auto squared = a.square(ctx);          // Square

int64_t value = sum.decrypt(ctx, keys);  // Decrypt to get result

Encryptor / Decryptor

File encryption and decryption.

sealcrypt::Encryptor encryptor(ctx);
encryptor.encryptFile("input.txt", "output.enc", keys);

sealcrypt::Decryptor decryptor(ctx);
decryptor.decryptFile("output.enc", "decrypted.txt", keys);

CMake Integration

cmake_minimum_required(VERSION 3.12)
project(MyProject)

set(CMAKE_CXX_STANDARD 17)

find_package(sealcrypt REQUIRED)

add_executable(myapp main.cpp)
target_link_libraries(myapp PRIVATE sealcrypt::sealcrypt)

Testing

cd build
make
ctest --output-on-failure

Security Levels

Level	Poly Modulus	Security	Speed
Low	4096	128-bit	Fastest
Medium	8192	192-bit	Balanced
High	16384	256-bit	Slowest

Key Components

• CryptoContext: Shared encryption parameters and SEAL context
• KeyPair: Public/secret key management with save/load support
• HomomorphicInt: Encrypted integers with operator overloading
• Encryptor: File encryption using homomorphic encryption
• Decryptor: File decryption with correct handling of all byte values
• FileHandler: File I/O utilities