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Is it possible to recreate the xpub key if I have multiple public addresses with their corresponding private keys? All the keys were created from the same HD wallet.
I was hodling and watching my wallets using the addressbalance query from blockchain.info, but since moving my funds, I'd like to watch it from the xpub address but no longer have access to the app that created the private keys...
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No, it is not possible. BIP 32 uses a combination of a hash function and Elliptic Curve Point Multiplication in order to derive the child keys (both public and private). Since both hashing and EC point multiplication are one way functions, you cannot find the inputs to those functions given just the outputs (i.e. child public or private keys). Thus you cannot derive the parent extended public key or extended private key given just many child public or private keys.
