Clarify the sighash types for HTLC Success and Timeout transactions (#…

…954)
lightning · Jan 31, 2022 · d975de1 · d975de1
1 parent 29db92f
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diff --git a/03-transactions.md b/03-transactions.md
@@ -328,7 +328,7 @@ These HTLC transactions are almost identical, except the HTLC-timeout transactio
 * txout count: 1
    * `txout[0]` amount: the HTLC amount minus fees (see [Fee Calculation](#fee-calculation))
    * `txout[0]` script: version-0 P2WSH with witness script as shown below
-* if `option_anchors` applies to this commitment transaction, `SIGHASH_SINGLE|SIGHASH_ANYONECANPAY` is used.
+* if `option_anchors` applies to this commitment transaction, `SIGHASH_SINGLE|SIGHASH_ANYONECANPAY` is used as described in [BOLT #5](05-onchain.md#generation-of-htlc-transactions).
 
 The witness script for the output is:
 

diff --git a/05-onchain.md b/05-onchain.md
@@ -594,8 +594,8 @@ If `option_anchors` does not apply to the commitment transaction, then
 HTLC-timeout and HTLC-success transactions are complete transactions with
 (hopefully!) reasonable fees and must be used directly.
 
-Otherwise, the use of `SIGHASH_SINGLE|SIGHASH_ANYONECANPAY` on the HTLC
-signatures received from the peer allows HTLC transactions to be combined with
+Otherwise, `SIGHASH_SINGLE|SIGHASH_ANYONECANPAY` MUST be used on the
+HTLC signatures received from the peer, as this allows HTLC transactions to be combined with 
 other transactions.  The local signature MUST use `SIGHASH_ALL`, otherwise
 anyone can attach additional inputs and outputs to the tx.