ripple-dot-net failing to sign accountSet with message key

[jargoman]

As the title suggests I am trying to sign an account set transaction using ripple-dot-net
https://github.com/ripple/ripple-dot-net

The first thing I tried was simply copying an ethereum address into the message-key box in my wallet. This produced and error:
Exception while signing. Not a number. 

So the next thing I tried was converting the string to it's hex equivalent:
Exception while signing. error parsing bool value

This led me to believe that I was feeding invalid json to ripple-dot-net. I added quotation marks to the hex string and this seemed to work now the error I get is
telBAD_PUBLIC_KEY

JSON being fed into ripple-dot-net is

{
"TransactionType": "AccountSet",
"Account": "rUxMbZQPHS84Jm7EvC3SKdaHLAkrx2qFwB",
"Fee": "10",
"LastLedgerSequence": 9925595,
"Sequence": 9923415,
"MessageKey": "f53b48a78b7b5111347b4ded5769baa11f65ea26"
}

My two questions are?

1. Why is it failing?

2. How would I set the message-key for the spark giveaway? do I remove the 0x to make it valid hex or do I convert the entire eth address to hex?

[Flintstone]

@jargoman https://coil.com/p/wietse/Prepare-for-claiming-your-Spark-token-Flare-Networks-a-tool-for-XUMM-XRPToolkit/NkXJQUqpi

Take a ETH-compatible public account addressyou own the private key (or secret, like mnemonic, seed, ...) of, eg. 0x415f8315c9948Ad91e2Cce5b8583A36dA431fb61

Strip the first two characters, and turn the string to upper case characters: 415F8315...A431FB61

Prepend 02 and 24 zeroes: 020000...000415F8315...A431FB61

Store this value in the MessageKey field on your XRP ledger account (on ledger) using an AccountSet transaction

[jargoman]

4 minutes ago, Flintstone said:

@jargoman https://coil.com/p/wietse/Prepare-for-claiming-your-Spark-token-Flare-Networks-a-tool-for-XUMM-XRPToolkit/NkXJQUqpi

Take a ETH-compatible public account addressyou own the private key (or secret, like mnemonic, seed, ...) of, eg. 0x415f8315c9948Ad91e2Cce5b8583A36dA431fb61

Strip the first two characters, and turn the string to upper case characters: 415F8315...A431FB61

Prepend 02 and 24 zeroes: 020000...000415F8315...A431FB61

Store this value in the MessageKey field on your XRP ledger account (on ledger) using an AccountSet transaction

do you know what the 02000... is for? Will that stop it from failing?

[jargoman]

5 minutes ago, jargoman said:

do you know what the 02000... is for? Will that stop it from failing?

IT WORKED !!!!!!!!!!!!!!!

I can't believe it. 

Do you know why? Was it converting it to capitals? I think that's why, I was converting it to lower case because one of my errors was unexpected char 'F'. It must have been invalid json.

[Flintstone]

6 minutes ago, jargoman said:

do you know what the 02000... is for? Will that stop it from failing?

Not a clue. I’d assume so. You can be the guinea pig  

[jargoman]

1 minute ago, Flintstone said:

Not a clue. I’d assume so. You can be the guinea pig  

My other theory is that the key must be a specific size. Maybe the size of a hexadecimal ripple address