# Bitcoin Inqusition 29.2

**URL:** <https://delvingbitcoin.org/t/bitcoin-inqusition-29-2/2236>\
**Category:** Implementation\
**Tags:** announcement, inquisition\
**Created:** [February 7, 2026, 12:21pm UTC](https://delvingbitcoin.org/t/bitcoin-inqusition-29-2/2236 "2026-02-07T12:21:40Z")\
**Posts on this page:** 1\
**Showing post:** 6

<div class="post-metadata">

**Author:** ![AaronZhang](https://delvingbitcoin.org/user_avatar/delvingbitcoin.org/aaronzhang/32/1823_2.png) [@AaronZhang](https://delvingbitcoin.org/u/AaronZhang)\
**Post date:** [March 25, 2026, 3:10am UTC](https://delvingbitcoin.org/t/bitcoin-inqusition-29-2/2236/6 "2026-03-25T03:10:26Z")

</div>

Following up on my earlier CAT/CSFS/CTV runs, I tested an **IK + CSFS** composition on Bitcoin Inquisition.

This uses OP\_INTERNALKEY to source the pubkey from Taproot execution context rather than witness.

Commit: [9930e922…0ea8](https://mempool.space/signet/tx/9930e922036a80d04a96a4b08f15838bcb880ce2a4be91da0b24af1484e10ea8?showDetails=true)

Reveal: [8d0b2156…dd8f](https://mempool.space/signet/tx/8d0b2156e9425afe64cabf3c906da255b6b86c51cb8968f828d5253fc261dd8f?showDetails=true)

Script: OP\_INTERNALKEY OP\_CHECKSIGFROMSTACK (cbcc)

Witness: [sig, message] — no pubkey in witness

Observation:

- Pubkey is no longer caller-supplied
- It is sourced from Taproot execution context (internal key)

This shifts authorization from “who provides a key” to “who created the UTXO”.

However, since the message is fixed, the (sig, message) pair is replayable across UTXOs with the same internal key.

Full breakdown (stack / control block / derivation): details: [https://medium.com/@aaron.recompile/op-internalkey-op-checksigfromstack-on-signet-identity-bound-authorization-04f0440557bc](https://medium.com/@aaron.recompile/op-internalkey-op-checksigfromstack-on-signet-identity-bound-authorization-04f0440557bc)

---

_[View the full topic](https://delvingbitcoin.org/t/bitcoin-inqusition-29-2/2236)._