Why load private key but offset is public key size?

Firmware
1


149 line extract_public_rsa_key(queue+52, core_private_key);
153 line const int len = 52+MAX_DEVICE_PUBLIC_KEY_LENGTH;


  LOG(INFO,"Encrypting handshake nonce");
  extract_public_rsa_key(queue+52, core_private_key);

  rsa_context rsa;
  init_rsa_context_with_public_key(&rsa, server_public_key);
  const int len = 52+MAX_DEVICE_PUBLIC_KEY_LENGTH;
#ifdef USE_MBEDTLS
  err = mbedtls_rsa_pkcs1_encrypt(&rsa, mbedtls_default_rng, nullptr, MBEDTLS_RSA_PUBLIC, len, queue, queue + len);
#else
  err = rsa_pkcs1_encrypt(&rsa, RSA_PUBLIC, len, queue, queue + len);
#endif
rsa_free(&rsa);