From 981a1423a9c5a5746635b8c8aa0bb557abf37fab Mon Sep 17 00:00:00 2001
From: Brandon Black <brandon@bliz.me>
Date: Fri, 22 Dec 2023 17:17:24 -0800
Subject: [PATCH] Add bip-internalkey

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 bip-internalkey.mediawiki | 68 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 bip-internalkey.mediawiki

diff --git a/bip-internalkey.mediawiki b/bip-internalkey.mediawiki
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+<pre>
+  BIP: TBD
+  Layer: Consensus (soft fork)
+  Title: INTERNALKEY
+  Author: Brandon Black <freedom@reardencode.com>
+  Comments-Summary: No comments yet.
+  Status: Draft
+  Type: Standards Track
+  Created: 2023-12-22
+  License: PD
+</pre>
+
+==Abstract==
+
+This BIP describes a new tapscript opcode (OP_INTERNALKEY) which pushes the
+taproot internal key to the stack.
+
+==Specification==
+
+When verifying taproot script spends having leaf version 0xc0 (as defined in
+BIP342), OP_INTERNALKEY replaces OP_SUCCESS187 (0xbb). OP_INTERNALKEY pushes
+the taproot internal key, as defined in BIP341, to the stack.
+
+==Motivation==
+
+When building taproot output restrictions, especially those secured by an
+aggregate key representing more than 1 signer, where the parties may wish to
+collaborate on signing with the taproot internal key, but only with additional
+script restrictions. In this case, OP_INTERNALKEY saves 32 bytes of witness
+space.
+
+In cases where script path spending is not desired, the internal key may be set
+to a NUMS point whose bytes would otherwise be required in a tapscript. This
+could be used with any hash locked transaction, for example, to save 32 witness
+bytes.
+
+==Reference Implementation==
+
+A reference implementation is provided in provided here:
+
+https://github.com/brandonblack/bitcoin/commit/aa94c2865badc9bef86c29c330d4da77f341c0f2
+
+==Backward Compatibility==
+
+By constraining the behavior of an OP_SUCCESS opcode, deployment of the BIP can
+be done in a backwards compatible, soft-fork manner. If anyone were to rely on
+the OP_SUCCESS behavior of OP_SUCCESS187, OP_INTERNALKEY would invalidate their
+spend.
+
+==Deployment==
+
+TBD
+
+==Credits==
+
+Jeremy Rubin described most of the ideas for OP_INTERNALKEY to me.
+
+==References==
+
+[https://github.com/bitcoin/bips/blob/master/bip-0341.mediawiki BIP 341] Taproot
+
+[https://github.com/bitcoin/bips/blob/master/bip-0342.mediawiki BIP 342] Tapscript
+
+==Copyright==
+
+This document is placed in the public domain.
+
+