Key derivation are unclear

Question

• I watch this video on Key Derivation process (https://www.youtube.com/watch?v=4tSQBK75CPU&t=722s). Basically, from mnemonic phrase --> create root key --> create public addresses
• Then, I see another tutorial to create payment address. https://developers.cardano.org/docs/stake-pool-course/handbook/keys-addresses/ I can create payment address without any mnemonic phrase or root key

The two all above are the process to create addresses, but they are a little different, which I could not understand.

I have 3 questions

1. Why in the tutorial, we can create payment address without mnemonic phrase?

2. In the tutorial, there is no step to create root key. What is the root key? It is verification key?

3. The video says that we can create multiple addresses from the root key. I tried to create different addresses using the below command, but they all generated the same address. How can I generate different addresses by using cardano-cli?

cardano-cli address build \
    --payment-verification-key-file payment.vkey \
    --stake-verification-key-file stake.vkey \
    --out-file payment.addr \
    --mainnet

Any hint would help me a lot. Thank you

Answer 1

You're mixing up between an HD Wallet and payment/stake address keys. HD Wallet is off-chain concept, creating root keys for which are described here.

You'd essentially be able to derive root key of HD wallet using mnemonics and then derive the address by following the derivation paths, as explained here.