From: vjudeu <vjudeu@gazeta•pl>
To: "bitcoin-dev@lists•linuxfoundation.org"
<bitcoin-dev@lists•linuxfoundation.org>
Subject: [bitcoin-dev] Sum of the keys attack on taproot
Date: Sat, 15 May 2021 12:21:00 +0200 [thread overview]
Message-ID: <131606955-6366ea10aec2eec765339d72e7c936ab@pmq5v.m5r2.onet> (raw)
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We have some taproot address with private key "a" and public key "a*G", owned by Alice. Bob wants to take Alice's coins without her permission. He owns taproot address with private key "b" and public key "b*G". He knows "a*G" by exploring the chain and looking for P2TR outputs. To grab Alice's funds, he creates "(b-a)*G" taproot address and send some small amount to this address. Then, Bob can create a transaction with two inputs, taking coins from "a*G" and "(b-a)*G" addresses. All that is needed is producing a signature matching the sum of the public keys used in taproot, which is "(a+b-a)*G", reduced to "b*G", so Bob uses his "b" private key to produce Schnorr signature. Is there any protection from this attack?
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next reply other threads:[~2021-05-15 10:21 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-15 10:21 vjudeu [this message]
2021-05-15 20:25 ` Tim Ruffing
2021-05-15 20:35 ` Ruben Somsen
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