@keep-network/tbtc-v2 revealing P2PKH deposit with a wrapped P2SH script
# Overview
P2PKH has 20 bytes just like P2SH. We protect against revealing P2PKH deposits by manually assembling the expected P2SH script in the smart contract and comparing hashes. However, we missed the case when the attacker embeds a valid P2SH inside of P2PKH as an output script. bitcoin-spv library [extracts the P2SH from P2PKH](https://github.com/keep-network/bitcoin-spv/blob/856849612ef49114af18c0f407eaa74afc2ee4be/solidity/contracts/BTCUtils.sol#L610-L612) and we treat it as a valid P2SH output.
This does not lead to stealing funds but can lead to protocol insolvency.
The off-chain client handles this case correctly, but the proble
SPV Merkle proof malleability allows the maintainer to prove invalid transactions
## Summary
By publishing specially crafted transactions on the Bitcoin blockchain, the SPV maintainer can produce seemingly valid SPV proofs for fraudulent transactions.
The issue was originally identified by Least Authority in the tBTC Bridge V2 Security Audit Report as _Issue B: Bitcoin SPV Merkle Proofs Can Be Faked_. A mitigation was believed to have been in place, but this turned out to contain an error, and the issue had not been effectively mitigated.
### Details
This is achieved by creating a 64-byte transaction that the fraudulent transaction treats as a node in its merkle proof:
The attacker creates the malicious transaction `E`