ECC private key is longer than public key

Question

I have generated ECC public and private key using secp192r1 curve. I get 75 for public and 125 for private encoded key array length. Why private key is longer than public key? W

Answer 1

Code fragment below outputs 24 bytes private key:

Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());

ECNamedCurveParameterSpec spec = ECNamedCurveTable.getParameterSpec("secp192r1");

KeyPairGenerator g = KeyPairGenerator.getInstance("ECDSA", "BC");
g.initialize(spec, new SecureRandom());
KeyPair pair = g.generateKeyPair();
ECPrivateKey ecPrivateKey = (ECPrivateKey)pair.getPrivate();

System.out.println(ecPrivateKey.getS().toByteArray().length);