Parent extended public key is the same as child extended public key?

[mark2021blue]

Describe the bug
Parent extended public key is the same as child extended public key?

Expected behavior
Are the two xpubs "m/44'/3'/0'/0/0" and "m/44'/3'/1'/0/0" the same correct code?
My understanding:
"m/44'/3'/0'/0/0" TWHDWalletGetExtendedPublicKey Gets the parent extended public key
"m/44'/3'/1'/0/0" TWAccountExtendedPublicKey Get child extended public key

Additional context
auto secretMnemonict1 = TWStringCreateWithUTF8Bytes(mnemonic1);
TWHDWallet* walletImpt1 = TWHDWalletCreateWithMnemonic(secretMnemonict1, TWStringCreateWithUTF8Bytes(""));
TWStringDelete(secretMnemonict1);

        auto customDerivationPatht1 = TWStringCreateWithUTF8Bytes("m/44'/3'/0'/0/0");
        TWPrivateKey* secretPrivateKeyCustomt1 = TWHDWalletGetKey(walletImpt1, TWCoinType::TWCoinTypeDogecoin, customDerivationPatht1);
        TWStringDelete(customDerivationPatht1);
        string xpub = TWStringUTF8Bytes(TWHDWalletGetExtendedPublicKey(walletImpt1, TWPurposeBIP44, TWCoinTypeDogecoin, TWHDVersionDGUB));
        cout << "+++++++ xpub1:" << xpub << endl;

        auto customDerivationPath2 = TWStringCreateWithUTF8Bytes("m/44'/3'/1'/0/0");
        TWPrivateKey* secretPrivateKeyCustom2 = TWHDWalletGetKey(walletImpt1, TWCoinType::TWCoinTypeDogecoin, customDerivationPath2);
      //  TWStringDelete(customDerivationPath2);
        string addressCustom2 = TWStringUTF8Bytes(TWCoinTypeDeriveAddress(TWCoinType::TWCoinTypeDogecoin, secretPrivateKeyCustom2));
        cout << "+++++++++++ doge Custom-derived address:   '" << addressCustom2 << "'" << endl;

        TWString* aC2 = TWCoinTypeDeriveAddress(TWCoinType::TWCoinTypeDogecoin, secretPrivateKeyCustom2);
        TWString* pxpub = TWHDWalletGetExtendedPublicKey(walletImpt1, TWPurposeBIP44, TWCoinTypeDogecoin, TWHDVersionDGUB);
        TWAccount* accountT1 = TWAccountCreate(aC2, TWCoinType::TWCoinTypeDogecoin, customDerivationPath2, pxpub);
      //  TWAccountExtendedPublicKey(accountT1);

        string xpub2 = TWStringUTF8Bytes(TWAccountExtendedPublicKey(accountT1));
        string adp2 = TWStringUTF8Bytes(TWAccountDerivationPath(accountT1));
        cout << "+++++++ xpub2:" << xpub2 << " Custom-derived address:   '" << TWStringUTF8Bytes(aC2) << "' adp:" << adp2 << endl;
        cout << endl;

[optout21]

In the line

TWString* pxpub = TWHDWalletGetExtendedPublicKey(walletImpt1, TWPurposeBIP44, TWCoinTypeDogecoin, TWHDVersionDGUB);

TWHDWalletGetExtendedPublicKey uses the default derivation path, that is m/44'/3'/0'/0/0 (and not m/44'/3'/1'/0/0).
Therefore in the next line in TWAccountCreate the provided derivation path and public key are not consistent.
If you compare derivation of xpub and pxpub, they are the same line, so they will be the same value.

[mark2021blue]

Thanks for your answer!
Feel sorry! Maybe I didn't express or understand clearly, for a mnemonic, is the xpub of the default Derivation Path or the custom Derivation Path the same? If it is different, I want to calculate the child extended public key through TWHDWalletGetExtendedPublicKey and TWAccountExtendedPublicKey. I don't know what the problem is?
Thanks!

[mark2021blue]

The following interface parameters cannot specify custom Derivation Path
TWString *_Nonnull TWHDWalletGetExtendedPublicKey(struct TWHDWallet *_Nonnull wallet, enum TWPurpose purpose, enum TWCoinType coin, enum TWHDVersion version);

[mark2021blue]

The purpose of sharing the parent extended public key is so that child public keys (and thus addresses) can be derived from it，The default address is obtained by the following methods, and the derived address of the customDerivationPath2 cannot be obtained

TWPublicKey* pk1 = TWHDWalletGetPublicKeyFromExtended(TWAccountExtendedPublicKey(accountT1), TWCoinType::TWCoinTypeDogecoin, customDerivationPath2);
TWAnyAddress* pk1addr = TWAnyAddressCreateWithPublicKey(pk1, TWCoinType::TWCoinTypeDogecoin);
cout << "+++++++++++ pk1addr:" << TWStringUTF8Bytes(TWAnyAddressDescription(pk1addr)) << endl;

[mark2021blue]

The extendedPublicKey parameter in the following interface, I understand it is the master/parent extended public key, I want to obtain the child extended public key of the corresponding address of the derivationPath through TWAccountCreate, TWAccountExtendedPublicKey, etc.

struct TWAccount *_Nonnull TWAccountCreate(TWString *_Nonnull address, enum TWCoinType coin, TWString *_Nonnull derivationPath, TWString *_Nonnull extendedPublicKey);

[mark2021blue]

[optout21]

As I written above, I have not found a way to obtain extended HD private key for a custom derivation path.
I have raised issue #2084 to add support for this.

[mark2021blue]

Thank you very much! ! !

[optout21]

Note: PR has been merged #2085

[mark2021blue]

great news!
@catenocrypt @hewigovens Thank you very much! ! !