Merge pull request bitcoin#990 from dr-orlovsky/patch-3

BIp 174: fixing typo in rationale reference with closed tag

bip-0174.mediawiki

@@ -373,7 +373,7 @@ The Signer must only accept a PSBT.
 The Signer must only use the UTXOs provided in the PSBT to produce signatures for inputs.
 Before signing a non-witness input, the Signer must verify that the TXID of the non-witness UTXO matches the TXID specified in the unsigned transaction.
 Before signing a witness input, the Signer must verify that the witnessScript (if provided) matches the hash specified in the UTXO or the redeemScript, and the redeemScript (if provided) matches the hash in the UTXO.
-The Signer may choose to fail to sign a segwit input if a non-witness UTXO is not provided. <ref>'''Why would non-witness UTXOs be provided for segwit inputs?''' The sighash algorithm for Segwit specified in BIP 173 is known to have an issue where an attacker could trick a user to sending Bitcoin to fees if they are able to convince the user to sign a malicious transaction multiple times. This is possible because the amounts in <tt>PSBT_IN_WITNESS_UTXO<tt> of other segwit inputs can be modified without effecting the signature for a particular input. In order to prevent this kind of attack, many wallets are requiring that the full previous transaction (i.e. <tt>PSBT_IN_NON_WITNESS_UTXO</tt>) be provided to ensure that the amounts of other inputs are not being tampered with.</ref>
+The Signer may choose to fail to sign a segwit input if a non-witness UTXO is not provided. <ref>'''Why would non-witness UTXOs be provided for segwit inputs?''' The sighash algorithm for Segwit specified in BIP 173 is known to have an issue where an attacker could trick a user to sending Bitcoin to fees if they are able to convince the user to sign a malicious transaction multiple times. This is possible because the amounts in <tt>PSBT_IN_WITNESS_UTXO</tt> of other segwit inputs can be modified without effecting the signature for a particular input. In order to prevent this kind of attack, many wallets are requiring that the full previous transaction (i.e. <tt>PSBT_IN_NON_WITNESS_UTXO</tt>) be provided to ensure that the amounts of other inputs are not being tampered with.</ref>
 The Signer should not need any additional data sources, as all necessary information is provided in the PSBT format.
 The Signer must only add data to a PSBT.
 Any signatures created by the Signer must be added as a "Partial Signature" key-value pair for the respective input it relates to.