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-rw-r--r--bip-0141.mediawiki4
1 files changed, 2 insertions, 2 deletions
diff --git a/bip-0141.mediawiki b/bip-0141.mediawiki
index 27a59f9..8fdc795 100644
--- a/bip-0141.mediawiki
+++ b/bip-0141.mediawiki
@@ -98,9 +98,9 @@ If the version byte is 0, and the witness program is 32 bytes:
* The <code>witnessScript</code> is deserialized, and executed after normal script evaluation with the remaining witness stack (≤ 520 bytes for each stack item).
* The script must not fail, and result in exactly a single TRUE on the stack.
-If the version byte is 0, but the witness program is neither 20 nor 32 bytes, the script must fail.
+If the version byte is 0, but the witness program is neither 20 nor 32 bytes, the script must fail.<ref>For example, a scriptPubKey with OP_0 followed by a 40-byte non-zero data push will fail due to incorrect program size. However, a scriptPubKey with OP_0 followed by a 41-byte non-zero data push will pass, since it is not considered to be a witness program</ref>
-If the version byte is 1 to 16, no further interpretation of the witness program or witness happens, and there is no size restriction for the witness. These versions are reserved for future extensions.
+If the version byte is 1 to 16, no further interpretation of the witness program or witness stack happens, and there is no size restriction for the witness stack. These versions are reserved for future extensions.<ref>For backward compatibility, for any version byte from 0 to 16, the script must fail if the witness program has a <code>CastToBool</code> value of zero. However, having a hash like this is a successful preimage attack against the hash function, and the risk is negligible.</ref>
=== Other consensus critical limits ===