To prove that a key is the nth hardened child, you need to provide I_L and prove that it is the result of a HMAC_SHA512 operation. I don't see how you can prove the latter without giving the second operand of this operation. However, for a hardened step this contains the private key.
Topic: BIP-32 hardened children (Read 723 times)
Can an observer prove that a given public key is the nth hardened child of a given xpub without access to any of the associated private keys if they know n?
Alternately, can the owner of the private keys create such a proof?
Alternately, can the owner of the private keys create such a proof?
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