bool MessageCrypto::decryptData()

in lib/MessageCrypto.cc [394:459]
56 lines of code
9 McCabe index (conditional complexity)

bool MessageCrypto::decryptData(const std::string& dataKeySecret, const proto::MessageMetadata& msgMetadata,
                                SharedBuffer& payload, SharedBuffer& decryptedPayload) {
    // unpack iv and encrypted data
    msgMetadata.encryption_param().copy(reinterpret_cast<char*>(iv_.get()),
                                        msgMetadata.encryption_param().size());

    EVP_CIPHER_CTX* cipherCtx = NULL;
    decryptedPayload = SharedBuffer::allocate(payload.readableBytes() + EVP_MAX_BLOCK_LENGTH + tagLen_);
    if (PULSAR_UNLIKELY(logger()->isEnabled(Logger::LEVEL_DEBUG))) {
        std::string strHex = stringToHex(payload.data(), payload.readableBytes());
        LOG_DEBUG(logCtx_ << "Attempting to decrypt data with encrypted size " << payload.readableBytes()
                          << ", data = " << strHex);
    }

    if (!(cipherCtx = EVP_CIPHER_CTX_new())) {
        LOG_ERROR(logCtx_ << " Failed to get cipher ctx");
        return false;
    }

    if (!EVP_DecryptInit_ex(cipherCtx, EVP_aes_256_gcm(), NULL,
                            reinterpret_cast<unsigned const char*>(dataKeySecret.c_str()),
                            reinterpret_cast<unsigned const char*>(iv_.get()))) {
        LOG_ERROR(logCtx_ << " Failed to init decrypt cipher ctx");
        EVP_CIPHER_CTX_free(cipherCtx);
        return false;
    }

    if (EVP_CIPHER_CTX_set_padding(cipherCtx, EVP_CIPH_NO_PADDING) != 1) {
        LOG_ERROR(logCtx_ << " Failed to set cipher padding");
        EVP_CIPHER_CTX_free(cipherCtx);
        return false;
    }

    int cipherLen = payload.readableBytes() - tagLen_;
    int decLen = 0;
    if (!EVP_DecryptUpdate(cipherCtx, reinterpret_cast<unsigned char*>(decryptedPayload.mutableData()),
                           &decLen, reinterpret_cast<unsigned const char*>(payload.data()), cipherLen)) {
        LOG_ERROR(logCtx_ << " Failed to decrypt update");
        EVP_CIPHER_CTX_free(cipherCtx);
        return false;
    };
    decryptedPayload.bytesWritten(decLen);

    if (!EVP_CIPHER_CTX_ctrl(cipherCtx, EVP_CTRL_GCM_SET_TAG, tagLen_, (void*)(payload.data() + cipherLen))) {
        LOG_ERROR(logCtx_ << " Failed to set gcm tag");
        EVP_CIPHER_CTX_free(cipherCtx);
        return false;
    }

    if (!EVP_DecryptFinal_ex(cipherCtx, reinterpret_cast<unsigned char*>(decryptedPayload.mutableData()),
                             &decLen)) {
        LOG_ERROR(logCtx_ << " Failed to finalize encrypted message");
        EVP_CIPHER_CTX_free(cipherCtx);
        return false;
    }
    decryptedPayload.bytesWritten(decLen);
    if (PULSAR_UNLIKELY(logger()->isEnabled(Logger::LEVEL_DEBUG))) {
        std::string strHex = stringToHex(decryptedPayload.data(), decryptedPayload.readableBytes());
        LOG_DEBUG(logCtx_ << "Data decrypted. Decrypted size = " << decryptedPayload.readableBytes()
                          << ", data = " << strHex);
    }

    EVP_CIPHER_CTX_free(cipherCtx);

    return true;
}