Can I import a 256 bit private key in a Wallet (binary format)? Or do I have to convert it in another format?
2 Answers
dumpprivkey
in bitcoin core returns private key in WIF
importprivkey
adds a private key (as returned by dumpprivkey) to your wallet.
Private key to WIF: https://bitcoin.stackexchange.com/a/99101/
Most wallets (and by that, I mean almost all) will not accept a binary 256 bit private key, you will have to convert your 1's and 0's to a WIF format.
There are libraries in python and javascript (and I'm sure other languages too) available that can do this function conversion for you.