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1

Yes and no. The X and Y coordinates of points on the secp256k1 curve are integers modulo p = 2256 - 232 - 977. Positive/negative don't exist there, as modulo p it holds for every a that -a = p-a. So, we need another criterion to distinguish the two solutions for y for the equation y2 = x3 + 7. There are a number of possibilities: High/low: we could simply ...


2

You can have multiple transactions sent to the same address (address reuse), it is just not recommended as it is not good for your privacy. (In this case you have multiple UTXOs that can be spent using the same private key.) A chain observer can see your increasing effective balance at that address rather than you receiving funds to multiple addresses and ...


0

The extended master key fingerprint on the coldcard is indeed the xpub of your wallet. It's just that the first 10 letters or so are equal to every wallet, but the rest is different


3

The encoding of an xpub contains multiple pieces of data: A 4-byte fixed prefix that results in the "xpub" prefix after encoding Depth in the tree (0 for all master xpubs, 1 for children thereof, ...) A 4-byte checksum of the parent key (0x00000000 for all master xpubs as they have no parent) The 4-byte index this node has in the derivation from ...


1

Using this library which is a pure python library with no dependencies (disclaimer: I am the author) >>> from cryptotools import Xprv >>> xprv = Xprv.from_mnemonic('assist excess fox blossom trouble cry must segment arrive stereo weather april pudding tuna change') >>> xpub = xprv.to_xpub() >>> xpub.encode() '...


0

According to the answer below, the ColdCard will update the the fingerprint after you apply the passphrase. You can also save the passphrase to a SD to avoid entering it each time. "You'll have to enter it in each time you restart the coldcard to access funds under that passphrase. Once you enter it and select "apply" it will update your ...


1

The following code using the python-bip32 lib can show this information. from bip32 import BIP32, HARDENED_INDEX bip32 = BIP32.from_seed(bytes.fromhex("01")) # get master xpriv and xpub master_xpriv = bip32.get_master_xpriv() master_xpub = bip32.get_master_xpub() print("master_xpriv: " + master_xpriv) print("master_xpub: " + ...


2

It's not possible, practically speaking. A P2PKH Bitcoin address is computed as RIPEMD160(SHA256(publickey)). Since public keys are unique, to find another keypair that results in the same address, you're essentially trying to find a hash collision on SHA256 or RIPEMD160, which is extremely difficult. The most "efficient" way to find such a ...


0

Is someone working on an emergency hardfork for switching to post-quantum signatures, just in case some surprisingly rapid progress in quantum computing is urging the issue?


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