How to get appropriately sized output from BGV packed plaintext

Library Questions
1

I modified a tutorial example as follows:

int main() {
    CCParams<CryptoContextBGVRNS> parameters;
    parameters.SetMultiplicativeDepth(2);
    parameters.SetPlaintextModulus(65537);
    CryptoContext<DCRTPoly> cryptoContext = GenCryptoContext(parameters);
    cryptoContext->Enable(PKE);
    cryptoContext->Enable(KEYSWITCH);
    cryptoContext->Enable(LEVELEDSHE);

    KeyPair<DCRTPoly> keyPair;
    keyPair = cryptoContext->KeyGen();
    cryptoContext->EvalMultKeyGen(keyPair.secretKey);
    cryptoContext->EvalRotateKeyGen(keyPair.secretKey, {1, 2, -1, -2});

    std::vector<int64_t> vectorOfInts1 = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12};
    Plaintext plaintext1               = cryptoContext->MakePackedPlaintext(vectorOfInts1);
    std::vector<int64_t> vectorOfInts2 = {3, 2, 1, 4, 5, 6, 7, 8, 9, 10, 11, 12};
    Plaintext plaintext2               = cryptoContext->MakePackedPlaintext(vectorOfInts2);

    auto ciphertext1 = cryptoContext->Encrypt(keyPair.publicKey, plaintext1);
    auto ciphertext2 = cryptoContext->Encrypt(keyPair.publicKey, plaintext2);

    std::cout << "Plaintext #1: " << plaintext1 << std::endl;
    std::cout << "Plaintext #2: " << plaintext2 << std::endl;
    std::cout << "\nResults of homomorphic computations" << std::endl;

    // auto ciphertextActual = test_binops(cryptoContext, ciphertext1, ciphertext2);
    auto v0 = cryptoContext;
    auto v1 = ciphertext1;
    auto v2 = ciphertext2;
    auto v3 = v0->EvalAdd(v1, v2);
    auto v4 = v0->EvalSub(v1, v2);
    auto v5 = v0->EvalMult(v3, v4);
    auto ciphertextActual = v5;

    Plaintext plaintextActual;
    cryptoContext->Decrypt(keyPair.secretKey, ciphertextActual, &plaintextActual);
    std::cout << "output without GetPackedValue: " << plaintextActual << std::endl;
    auto actual = plaintextActual->GetPackedValue();

    std::cout << "output with GetPackedValue: " << actual << std::endl;
    return 0;
}

The output is

output without GetPackedValue: ( -8 0 8 ... )                                                                                                                                                                                                 
output with GetPackedValue: [ -8 0 8 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 <many more zeroes follow> ]

Is there an API or utility function in OpenFHE that preserves the size of the input vector when decrypting the resulting output?

I can just std::vector::resize the result, but I wonder if I’m just missing that somewhere in the existing API.

2

Can you try the following after Decrypt:
plaintextActual->SetLength(<desired_length>);