This tool works, but requires share format conversion. It's not very easy, but doable.
Let's take this 2-of-3 example from the spec:...
Thanks for taking the time to put this together!
I got all the way up to "converting the result with Base58Check", thats where you lost me.
I did review
https://en.bitcoin.it/wiki/Base58Check_encoding but again, ended up feeling like it was greek.
This has been a good exercise, and I will continue learning about the cryptography, but I'm really looking for something the average guy can use (i.e. me) to easily assemble Shamir's Secret Sharing keys into a Bitcoin WIF private key, does this not exist?
Let's pick up where cetus left off.
There are tools on the web you can use to convert the private key from hex to WIF. For example, bitaddress.org.
Refer to my previous post.
To demonstrate the process: go to bitaddress.org and click on "wallet details.". Copy the private key
be1583452771c1def6789be9ab5086bf3c18dd47aa99d785056ba330bcda7aaf (64 hex characters = 256 bits, the length of a private key. The prepended hex characters 80 are not part of the private key.)
into the "private key" field. Bitaddres will then show the private key in WIF format, in text and qr code both.
For this example it's okay to work online; however, when the time comes to work with addresses containing real funds, you should work offline. To do this, save the HTML of bitaddress.org, disconnect from the internet, and bring up bitaddress.org from the file where you saved it. Bitaddress.org will run in your browser even when disconnected from the internet.
The safest way to save bitaddress.org is by downloading the HTML from github.
Apparently, passguardian shows a "reconstructed secret" with a couple of zeroes prepended. As I mentioned above, these extra characters aren't in the private key, properly defined. The private key consists of 64, count 'em, 64 hex characters for the statutory 256 bits.