Is the seed the same as the private key? about bip39

[dcousens]

Is the seed generated from mneumonicToSeed or mneumonicToSeedHex considering a private key

No

or master private key?

No

The seed is 64-bytes in length, and is used as entropy for private key generation. Private keys are 32-bytes in length, and have some numerical constraints.

[dcousens]

Huh, so the private key is just half the seed?

Indeed, after being HMAC'd.
You could simply do a .slice too, or you could HMAC-SHA256, or, or, or.

[arshbot]

Okay thanks. Do you know how I'd generate a private key from the seed?

[dcousens]

BIP32 does the following:

  let I = crypto.hmacSHA512('Bitcoin seed', seed)
  let IL = I.slice(0, 32)

Where IL is the private key (which is checked to be in the range [0, n].
If you intend to use the BIP32 standard, I'd suggest using a library to do this for you.

[arshbot]

Huh, so the private key is just half the seed? (Assuming the seed is 64 bits) I've found a ton of libraries that do this really well, but I'm really trying to perform stuff like privkey, address generation as manually as I can without performing intricate math myself.

[arshbot]

What's done with the right half of the seed if it isn't useful in recreating the wallet's functionality later on?

[dcousens]

@arshbot for BIP32, it is used as the chainCode, which is used in deriving BIP32 child nodes.