fix(abstract-eth,sdk-core): enforce signableHex/serializedTxHex consistency for BSC and XDC (WCI-1398) - #9526
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davidkaplanbitgo merged 3 commits intoAug 26, 2026
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…stency for BSC and XDC For TSS_VERIFY_USE_SERIALIZED_TX_HEX coins (BSC, XDC), the ECDSA MPCv2 signing flow calls verifyTransaction with serializedTxHex but then signs signableHex. Both values are server-supplied independently, allowing a malicious server to pair a benign serializedTxHex (shown to verify) with a tampered signableHex (what actually gets signed). Adds a CoinWithSignableConsistency interface to sdk-core, implemented by AbstractEthLikeNewCoins. After verifyTransaction succeeds, ecdsaMPCv2 calls assertSignableConsistency to derive the expected signableHex from serializedTxHex and throw InvalidTransactionError if they diverge. WCI-1398 Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com> TICKET: WCI-1398
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Summary
For BSC and XDC, the ECDSA MPCv2 signing flow verifies
serializedTxHexbut signssignableHex— both are independent server-supplied fields. This PR adds a consistency check that locally derives the expectedsignableHexfromserializedTxHexand throws before signing if they diverge.Changes
CoinWithSignableConsistencyinterface and type guard tosdk-coreAbstractEthLikeNewCoinsimplementsassertSignableConsistencyusingTransactionFactory.fromSerializedData, handling both EIP-1559 and legacy EIP-155 transactionsecdsaMPCv2.tscalls the check afterverifyTransactionsucceeds in theTSS_VERIFY_USE_SERIALIZED_TX_HEXbranchTest plan
signableHexthrows — BSC + XDC@wp_api_tbscand@wp_api_txdcpassed