Convert Base64 Private Key to WIF How do I get my private key from this? I found an old file on one of my hard drives with a wallet address and something that looks like this (changed for obvious reasons). 

What is this and how can I get my private key from it?

LZEuGNcDIJI5mRCATBouTmQgdpaycce0rDH/B//+w7v0hofB6+Apt0bepR8pUUxHEHAXHHAv7+67AHwh80Lx9g==


I tried this https://bitcoin.stackexchange.com/a/43438/105403. When I plug the WIF into bitaddress.org it's not matching my actual bitcoin address so I must be doing something wrong.
The following using libbitcoin bitcoin-explorer (bx) piped command lines, see documentation to better understand the two piped examples below.

The 512 bit output below, leads me to believe the base64 encoded key is an HD key that already might have BIP 39 conversion and possibly BIP 39 passphrase applied.

1% echo -n LZEuGNcDIJI5mRCATBouTmQgdpaycce0rDH/B//+w7v0hofB6+Apt0bepR8pUUxHEHAXHHAv7+67AHwh80Lx9g== | bx base64-decode | bx base16-encode
2d912e18d7032092399910804c1a2e4e64207696b271c7b4ac31ff07fffec3bbf48687c1ebe029b746dea51f29514c471070171c702fefeebb007c21f342f1f6

Let's assume the path is the following Bitcoin path m/44'/0'/0'/0/0, then the compressed WIF key can be computed as follows:

2% echo -n LZEuGNcDIJI5mRCATBouTmQgdpaycce0rDH/B//+w7v0hofB6+Apt0bepR8pUUxHEHAXHHAv7+67AHwh80Lx9g== | bx base64-decode | bx base16-encode | bx hd-new -v 76066276 | bx hd-private -d -i 44 | bx hd-private -d -i 0 | bx hd-private -d -i 0 | bx hd-private -i 0 | bx hd-private -i 0 | bx hd-to-ec | sed 's/$/01/' | bx base58check-encode -v 128

L2Xa6v3zo12E813ssicXbjEeatdXa37J5532WwtdXYRzgzL9QSxw

The associated public address is as follows:

3% echo -n LZEuGNcDIJI5mRCATBouTmQgdpaycce0rDH/B//+w7v0hofB6+Apt0bepR8pUUxHEHAXHHAv7+67AHwh80Lx9g== | bx base64-decode | bx base16-encode | bx hd-new -v 76066276 | bx hd-private -d -i 44 | bx hd-private -d -i 0 | bx hd-private -d -i 0 | bx hd-private -i 0 | bx hd-private -i 0 | bx hd-to-ec | bx ec-to-public | bx ec-to-address -v 0

17Wnq9Nm5KcFtvhunSPN9WRTZxTUvkvri5

Your HD path path might be different.