Importing private keys creates different address

Question

How does importing private keys work?

I have previously imported the private key for a 1Archive... address into Bitcoin Core and noted then it added an address like 1AXbRq... and I didn't follow it up further.

Today I have exported the private key for a 3... address from Bitcoin Core and imported it in Electrum. Electrum adds a 1... address and doesn't see any of the transactions.

How does this work? I understand that there is an underlying 1... address behind a SegWit address but how would I spend any BTC if it is not showing in my wallet balance? What else should I do?

If there is an answered question for this already on Bitcoin.SE I could not find it.

My private key begins with L.

Answer 1

I suspect you can import it directly from the console within Electrum (based on this PR). Currently, Electrum does now allow importing individual p2wpk inside p2sh addresses (the 3 segwit addresses). You can, however, still import an entire seed by using a BIP49 derivation path.

Try running the following in the electrum console:

key = 'your_key'
txin_type, secret, compressed = bitcoin.deserialize_privkey(key)
wif2 = bitcoin.serialize_privkey(secret, compressed, 'p2wpkh-p2sh')
print(wif2)

Then import the wif2 which it prints out

Answer 2

Prepend "p2wpkh-p2sh:" to the private key before importing it into Electrum. For example:

p2wpkh-p2sh:5Kkzs8XrJNAmf9VQDFeGBfaRvSByAvPK6DbDXw5BVqswWaXSG2Y

Answer 3

"I have previously imported the private key for a 1Archive... address into Bitcoin Core and noted then it added an address like 1AXbRq... and I didn't follow it up further."

First of all, I won't be answering the first question. It just sounds weird, and 99% it's caused by a mistake.

How does this work? I understand that there is an underlying 1... address behind a SegWit address but how would I spend any BTC if it is not showing in my wallet balance? What else should I do?

Here's how importing a P2PKH address works:

WIF result is affected by three parameters: Privkey type (a byte for BTC private keys), the private key (that also contains which y coordinate the pubkey has, if we want the compressed pubkey), and an extra 0x01 byte if we want the compressed pubkey. There's only one public key that can be generated using that WIF.

Here's how importing a P2SH address works:

1) Dump the WIF of the P2SH address

2) Import the WIF

3) Make a transaction, and watch how your wallet or Bitcoin Core doesn't recognize the transaction.

It won't recognize the transaction, because there's infinite number of P2SH addresses one can create using the WIF (Note: script has a size limit, so it's not infinite)!

To inform your wallet about your P2SH address, you should also import the script. And, this is not supported by 99.9% of the wallets. (However, the wallets can import Witness addresses, as they're standardized and widely used) That's why Electrum doesn't see your P2WPKH address, if you don't tell it to use the Witness address.