Derive the private key from Account seed hash in Waves

Question

I am starting my new waves blockchain by creating a jar file and start from the genesis block. It starts the node and shows the seed base58 hash and account as well as wallet data is stored in the wallet.dat file in encrypted form.

I am able to get account seed hash by API /addresses/seed/{address}. but I don't find where the seed is stored in text format or how can I derive the private key from it.

Link : https://docs.waves.tech/en/blockchain/waves-protocol/cryptographic-practical-details#creating-a-private-key-from-a-seed

In the above link, they give us libraries but they randomly select the seeds. but don't want that I want to provide my one seeds.

So the problems are as follows:

1. I don't find account or wallet seeds in text format only just their hash through API.
2. How can I generate the private key from the wallet.dat file where all information is encrypted.

Please do help.