polynomial modulus
coefficient modulus
plaintext modulus (只在BFV机制中)

coeff_modulus: { 50, 30, 30, 50, 50 }  +---+  Level 4 (all keys; `key level')|coeff_modulus: { 50, 30, 30, 50 }  +---+  Level 3 (highest `data level')|coeff_modulus: { 50, 30, 30 }  +---+  Level 2|coeff_modulus: { 50, 30 }  +---+  Level 1|coeff_modulus: { 50 }  +---+  Level 0 (lowest level)

//定义加密参数
EncryptionParameters encryptionParameters(scheme_type::CKKS);
size_t poly_modulus_degree = 8192;
encryptionParameters.set_poly_modulus_degree(poly_modulus_degree);
encryptionParameters.set_coeff_modulus(CoeffModulus::Create(poly_modulus_degree, {60,40,40,60}));
double scale = pow(2.0,40);
//创建加密上下文，并初始化相关实例
std::shared_ptr<SEALContext> context = SEALContext::Create(encryptionParameters);
KeyGenerator keyGenerator(context);auto public_key = keyGenerator.public_key();
auto secret_key = keyGenerator.secret_key();
auto relin_keys = keyGenerator.relin_keys();
const GaloisKeys galois_keys = keyGenerator.galois_keys();Encryptor encryptor(context, public_key);
Evaluator evaluator(context);
Decryptor decryptor(context, secret_key);CKKSEncoder encoder(context);
vector<double> test(1);
test.push_back(1.0);
//加密/解密操作都是在编码后的数据上进行
Plaintext test_plain;
Ciphertext test_cipher;
encoder.encode(test,scale, test_plain);
encryptor.encrypt(test_plain, test_cipher);
Plaintext plain_coeff1;
encoder.encode(3.0, scale, plain_coeff1);evaluator.multiply_plain_inplace(test_cipher,plain_coeff1);
evaluator.relinearize_inplace(test_cipher, relin_keys);
evaluator.rescale_to_next_inplace(test_cipher);Plaintext plain_test_result;
decryptor.decrypt(test_cipher, plain_test_result);
vector<double> test_result;
encoder.decode(plain_test_result, test_result);
print_vector(test_result, 4, 7);
//输出
/*
[ 0.0000000, 9.0000000, -0.0000000, -0.0000000, ..., -0.0000000, 0.0000000, -0.0000000, -0.0000000 ]
数组长度为 poly_modulus_degree/2
*/

[1.0,2.0,3.0,4.0]
//加密后
[c1,c2,c3,c4,...,c(0),c(0),c(0),c(0)] //这是一个密文

const int poly_modulus_degree_power = log2(poly_modulus_degree)
void rotate_sum(Evaluator& evaluator, Ciphertext& ciphertext, const GaloisKeys& keys){Ciphertext rotated;for (int i = 0; i < poly_modulus_degree_power - 1; ++i) {evaluator.rotate_vector(ciphertext, pow(2,i), keys, rotated);evaluator.add_inplace(ciphertext, rotated);}
}