š
Original date posted:2019-08-21
š Original message:Good morning Maxim,
The Deaf Bob Attack
===================
It seems to me that Bob can promote the N3 problem to the N2 problem.
Suppose Alice contacts Bob to get the data.
However, Bob happens to have lost the data in a tragic boating accident.
Now, supposedly what Alice does in this case would be to broadcast the HTLC settlement transaction, whose signature was provided by Bob during protocol setup.
But this seems unworkable.
* If Bob managed to sign the HTLC settlement transaction, what `SIGHASH` flags did Bob sign with?
* If it was `SIGHASH_ALL` or `SIGHASH_SINGLE`, then Bob already selected the decryption key at setup time.
* If it was `SIGHASH_NONE`, then Alice could put any SCRIPT, including `<Alice> OP_CHECKSIG`.
If Bob already selected the decryption key at setup time, then Bob can ignore Alice.
* If Alice does not publish the HTLC settlement transaction, then Bob will eventually enter the N2 state and get the stake+reward.
* If Alice *does* publish the HTLC settlement transaction, without Bob giving the encrypted data, then Bob can just use the hashlock and reveal the decryption key.
* The decryption key is useless without the encrypted data!
It seems this part is not workable?
As the decryption key is embedded in the HTLC, Alice cannot get a signature from Bob without the decryption key already being selected by Bob (and thus already claimable even without any data being returned by Bob).
Regards,
ZmnSCPxj
ZmnSCPxj [ARCHIVE] /
npub1g5ā¦3ms3l
2023-06-07 18:20:21
in reply to nevent1qā¦n6m8
Author Public Key
npub1g5zswf6y48f7fy90jf3tlcuwdmjn8znhzaa4vkmtxaeskca8hpss23ms3lPublished at
2023-06-07 18:20:21Event JSON
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Original date posted:2019-08-21\nš Original message:Good morning Maxim,\n\nThe Deaf Bob Attack\n===================\n\nIt seems to me that Bob can promote the N3 problem to the N2 problem.\n\nSuppose Alice contacts Bob to get the data.\nHowever, Bob happens to have lost the data in a tragic boating accident.\n\nNow, supposedly what Alice does in this case would be to broadcast the HTLC settlement transaction, whose signature was provided by Bob during protocol setup.\n\nBut this seems unworkable.\n\n* If Bob managed to sign the HTLC settlement transaction, what `SIGHASH` flags did Bob sign with?\n * If it was `SIGHASH_ALL` or `SIGHASH_SINGLE`, then Bob already selected the decryption key at setup time.\n * If it was `SIGHASH_NONE`, then Alice could put any SCRIPT, including `\u003cAlice\u003e OP_CHECKSIG`.\n\nIf Bob already selected the decryption key at setup time, then Bob can ignore Alice.\n\n* If Alice does not publish the HTLC settlement transaction, then Bob will eventually enter the N2 state and get the stake+reward.\n* If Alice *does* publish the HTLC settlement transaction, without Bob giving the encrypted data, then Bob can just use the hashlock and reveal the decryption key.\n * The decryption key is useless without the encrypted data!\n\nIt seems this part is not workable?\nAs the decryption key is embedded in the HTLC, Alice cannot get a signature from Bob without the decryption key already being selected by Bob (and thus already claimable even without any data being returned by Bob).\n\n\nRegards,\nZmnSCPxj",
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