Multisig xpub retrieval

[phoenix_btc]

Coinbase Vault multi-sig account, both seeds + password in hand, on paper, BUT the usbkey that I stored the three xpublic keys on is toast.

Per all of their documentation, the three xpub keys are available via the website under Vault details. However, that appears to not be true for my account. Support has been totally useless and non-responsive. I tried the mobile app as well, and multiple browsers.

Does anyone know how I may be able to "recover" what should be _public_ keys for my multisig account? 

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[achow101]

The paper backup that you made when you first made the Vault should contain your public keys. Retrieve them from there. If you don't have those, then you can generate them from the seeds that you have.

[phoenix_btc]

My paper backup consists of one shared seed, and one private seed (and I guess its associated password). If it's even possible, how might I generate the three xpub keys from that?

Essentially, I'm trying to use this:
https://github.com/coinbase/multisig-tool

PS - Thanks for relocating this to the appropriate forum!

[phoenix_btc]

As a brief update, I was able to retrieve Vault data from Coinbase's API. Unfortunately, no endpoints appear to return the three extended public keys. I tried using v1 and v2 calls to no avail.

If anyone has any other ideas, I'm all ears, but I'm pretty sure I'm dead in the water here. 

[achow101]

If you are willing to copy and paste some code and modify it slightly, this stackexchange answer: https://bitcoin.stackexchange.com/questions/57207/how-to-derive-the-private-key-associated-with-a-coinbase-multi-sig-vault-address/57215#57215 should solve most of your problems. It should get you the xpubs for the two seeds that you have, but for the private seed, you will need to first decrypt it. That can be done on bitaddress.org (download it and run offline, don't do it on the website itself).

[phoenix_btc]

Thanks for following up, your suggestions seemed very very promising! Unfortunately it looks like that script isn't compatible with the 12 word seed(s) that I have:
Traceback (most recent call last):
  File "xpub_cb.py", line 8, in <module>
    test_seed = decode_privkey(USER_SEED)
  File "/Library/Python/2.7/site-packages/pybitcointools/main.py", line 291, in decode_privkey
    if not formt: formt = get_privkey_format(priv)
  File "/Library/Python/2.7/site-packages/pybitcointools/main.py", line 271, in get_privkey_format
    bin_p = b58check_to_bin(priv)
  File "/Library/Python/2.7/site-packages/pybitcointools/main.py", line 473, in b58check_to_bin
    assert bin_dbl_sha256(data[:-4])[:4] == data[-4:]
AssertionError

 I setup my Vault almost immediately after Coinbase made it available, so I wonder if things may be a bit different compared to the current version.

[achow101]

Thanks for following up, your suggestions seemed very very promising! Unfortunately it looks like that script isn't compatible with the 12 word seed(s) that I have:
<snip>
 I setup my Vault almost immediately after Coinbase made it available, so I wonder if things may be a bit different compared to the current version.

12 word seeds aren't used anymore (if they were used at all in the first place). If you are using an older version of the coinbase multisig vault, I don't think I can help with that as I can't access such versions.