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Hi all I'm trying to develop my own deterministic key hierarchy with BIP-44 , BIP-39 and BIP-32. The initial part of the project is done:

  1. I generated the seed phrase thanks to BIP-39;
  2. I created my master node and its private key thanks to BIP-32;
  3. Now I'm trying to use branch paths to make my hierarchy work on other blockchains (I've already created addresses for BTC,ETH,BNB and SOL).

If I run my code, importing a previously generated seed phrase, the addresses I generated earlier become visible again, so it works. Unfortunately, however, it only works with the first three cryptocurrencies and not with Solana.

I show you the code I used to generate the Solana key pair (I used the module tweetnacl-js on Node.js)

> const path = \m/44'/501'/0'/0/0`;
> const child =masterNode.derivePath(path);
> console.log("\n---------Solana---------\n" )  
> const keyPair =nacl.sign.keyPair.fromSecretKey(child.privateKey); 
> const publicKeySol = bs58.encode(keyPair.publicKey);
> bs58.encode(keyPair.secretKey); 
> console.log(${coin} address:${publicKeySol});

As you can see, i used the function fromSecretKey to derive the private key. I think this is the right one. From documentation of tweetnacl-js. When I run the code, it (rightly) gives me this error: "Error: bad secret key size"

Since the private key that the master node generates is 32 bytes and is a Buffer, while the fromSecretKey function, from Doc , says: "Returns a signing key pair with public key corresponding to the given 64-byte secret key. The secret key must have been generated by nacl.sign.keyPair or nacl.sign.keyPair.fromSeed."

Is there a way to convert the child's private key to the correct format? Is there another library that allows you to do this that I don't know about? What do you think? I'm on the right track?

Thank you all in advance <3

1 Answer 1

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You're very close! Since you have the private key, you can derive the public key and create a normal keypair using fromSeed instead of fromSecretKey, as the docs say.

Here's the tweetnacl function in the docs: https://www.npmjs.com/package/tweetnacl#naclsignkeypairfromseedseed

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  • but the seed I should pass to the function, can't be child.privateKey , or can I put it? Should i pass the general seed of the master node? I don't think this should be used as it is needed to have access to all accounts, am I wrong?
    – AlexCav
    Apr 11, 2023 at 9:45
  • You should put child.privateKey. Unless I've misunderstood, the whole point is that you've derived the child seed from the master, and now you want a usable private key for the child, correct?
    – Jon C
    Apr 12, 2023 at 10:18
  • Yes, it's correct, so i should use this one. Thank you.
    – AlexCav
    Apr 12, 2023 at 10:56
  • Can i contact you in private for other questions for develop a crypto wallet non custodial?
    – AlexCav
    Apr 12, 2023 at 10:58
  • Sorry, I think it's better to keep conversations out in the open, that way you can get answers from more people!
    – Jon C
    Apr 12, 2023 at 15:14

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