user119698: I've followed the bip32 and bip39 specifications for generating the 512-bit seed, however I didn't understand how to generate the xpriv from this. I've used the left 256 bits for the private key and right 256 bits for the chain code, however my private key bytes and chaincode differs from the test vector:
Using 512-bit seed:
"d71de856f81a8acc65e6fc851a38d4d7ec216fd0796d0a6827a3ad6ed5511a30fa280f12eb2e47ed2ac03b5c462a0358d18d69fe4f985ec81778c1b370b652a8"
Desired Master Private Key bytes: "2fd0c70b975d9a38f84fba956ed795075fe43a85a45336143fe855551f1356db"
Desired Chaincode: "51fd417898af090d1a4dc040f4427a7e6a4ad5fd4024ace7f068a167861e8655"
Desired Xpriv: "xprv9s21ZrQH143K2shfP28KM3nr5Ap1SXjz8gc2rAqqMEynmjt6o1qboCDpxckqXavCwdnYds6yBHZGKHv7ef2eTXy461PXUjBFQg6PrwY4Gzq"

How do I obtain these values using the left 256 bits for the pk, and the right 256 bits for the chaincode?
Thanks.

user208: There are two separate processes:

BIP39 specifies how to go from a phrase/mnemonic to a seed, using 2048 iterations of HMAC-SHA512.
BIP32 specifies how to go from a seed to a master key (using another single HMAC-SHA512) and then how to derive child keys from that master key.

Perhaps you were missing that the master key is distinct from the seed, and that computing the xprv from the seed thus involves yet another HMAC-SHA512 step?

119698: <p>I've followed the bip32 and bip39 specifications for generating the 512-bit seed, however I didn't understand how to generate the xpriv from this. I've used the left 256 bits for the private key and right 256 bits for the chain code, however my private key bytes and chaincode differs from the test vector:</p>
<p>Using 512-bit seed:
&quot;d71de856f81a8acc65e6fc851a38d4d7ec216fd0796d0a6827a3ad6ed5511a30fa280f12eb2e47ed2ac03b5c462a0358d18d69fe4f985ec81778c1b370b652a8&quot;</p>
<pre><code>Desired Master Private Key bytes: &quot;2fd0c70b975d9a38f84fba956ed795075fe43a85a45336143fe855551f1356db&quot;
Desired Chaincode: &quot;51fd417898af090d1a4dc040f4427a7e6a4ad5fd4024ace7f068a167861e8655&quot;
Desired Xpriv: &quot;xprv9s21ZrQH143K2shfP28KM3nr5Ap1SXjz8gc2rAqqMEynmjt6o1qboCDpxckqXavCwdnYds6yBHZGKHv7ef2eTXy461PXUjBFQg6PrwY4Gzq&quot;
</code></pre>
<p>How do I obtain these values using the left 256 bits for the pk, and the right 256 bits for the chaincode?</p>
<p>Thanks.</p>
 208: <p>There are two separate processes:</p>
<ul>
<li>BIP39 specifies how to go from a phrase/mnemonic to a seed, using 2048 iterations of HMAC-SHA512.</li>
<li>BIP32 specifies how to go from a seed to a master key (using another single HMAC-SHA512) and then how to derive child keys from that master key.</li>
</ul>
<p>Perhaps you were missing that the master key is distinct from the seed, and that computing the xprv from the seed thus involves yet another HMAC-SHA512 step?</p>
