From: sashabeton <sashabeton2007@gmail.com>
To: Bitcoin Development Mailing List <bitcoindev@googlegroups.com>
Subject: Re: [bitcoindev] [BIP proposal] Pay to Schnorr Key Hash (P2SKH)
Date: Mon, 16 Mar 2026 07:36:43 -0700 (PDT) [thread overview]
Message-ID: <9e030d1e-0eab-4463-948e-ef3ec3c43b1bn@googlegroups.com> (raw)
In-Reply-To: <cc649b36-0ee1-4a87-b135-f5ad5a38b232n@googlegroups.com>
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On scriptability and OP-code upgradeability: P2SKH is explicitly a
single-key output type, the same as P2TR key-path spending. If you need
Tapscript or OP-code upgradeability, you use P2TR. P2SKH targets the same
use case as P2WPKH today: simple, high-volume payments where you have one
key and no script conditions. In that use case P2TR key-path spending
offers no scriptability either — this is not a new trade-off, it is the
same one Taproot already made.
On quantum security: the broader quantum-resistance question is legitimate,
but it applies equally to all of Bitcoin's current output types. A proper
solution requires a post-quantum signature scheme — a new cryptographic
assumption. Until such a scheme is designed, reviewed, and adopted by the
network (a multi-year process), there is value in keeping the 20-byte
hashed address format that wallets and users already know, while gaining
Schnorr efficiency. P2SKH offers exactly that bridge, without waiting for a
problem the entire ecosystem has yet to solve.
On Monday, 16 March 2026 at 12:57:52 UTC+1 Alex wrote:
> You are saving 12 bytes by removing all the scriptability, OP-code
> upgradeability and basically locking yourself to a non-quantum-secure key
> spend path that is only quantum secure if never spent? Or did I
> missunderstand?
>
> måndag 16 mars 2026 kl. 12:25:57 UTC+1 skrev Martin Habovštiak:
>
>> Taproot specifically did not do this for good reasons that are well
>> documented. I recommend you to read documentation first before attempting
>> to make changes.
>>
>> Dňa po 16. 3. 2026, 11:48 sashabeton <sashabe...@gmail.com> napísal(a):
>>
>>> Hi everyone,
>>>
>>> I'd like to propose a new native SegWit output type: Pay to Schnorr Key
>>> Hash (P2SKH).
>>>
>>> == The problem ==
>>>
>>> The two most relevant output types today each solve half the problem:
>>> - P2WPKH has a compact 22-byte scriptPubKey, but uses ECDSA and puts the
>>> full 33-byte compressed public key in the witness (~108 witness bytes per
>>> input).
>>> - P2TR uses Schnorr signatures (64-byte witness), but embeds the full
>>> 32-byte x-only public key directly in the scriptPubKey, making outputs 12
>>> bytes larger than P2WPKH and exposing the key in every unspent output.
>>>
>>> Neither type achieves both a compact output and a compact witness
>>> simultaneously.
>>>
>>> == The proposal ==
>>>
>>> P2SKH uses OP_2 <hash160(P.x)> as the scriptPubKey (22 bytes, same as
>>> P2WPKH). Spending requires a single 64-byte Schnorr signature. Verification
>>> works by key recovery: given the signature (R, s) and the challenge e =
>>> TaggedHash("P2SKH/challenge", R.x || hash160(P.x) || msg), the verifier
>>> recovers P = e^-1 * (s*G - R) and checks that hash160(P.x) matches the
>>> program. The sighash reuses the BIP341 transaction digest, so cross-version
>>> replay is prevented by the scriptPubKey commitment.
>>>
>>> The result is the smallest combined footprint of any current single-key
>>> output type — a 22-byte output with a 64-byte witness — while keeping the
>>> public key off-chain until spending.
>>>
>>> == Tradeoffs ==
>>>
>>> The key-recovery step costs roughly one extra field inversion and scalar
>>> multiplication compared to direct Schnorr verification. This is the price
>>> of the 12-byte output size reduction.
>>>
>>> == Open questions ==
>>>
>>> 1. BIP360 also claims witness version 2. If both proposals advance, one
>>> needs to move. Version 3 seems like a natural alternative for P2SKH.
>>> 2. Naming — "P2SKH" follows the established pattern but "P2TRKH" has
>>> been suggested to emphasise Schnorr/taproot lineage. Opinions welcome.
>>>
>>> Full draft:
>>> https://github.com/sashabeton/bips/blob/3cb9e07984b571e9510370ab7e7218620be580dc/p2skh.md
>>> PoC implementation: https://github.com/bitcoin/bitcoin/pull/34826
>>>
>>> Thanks in advance for any feedback.
>>>
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>>> .
>>>
>>
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next prev parent reply other threads:[~2026-03-16 15:45 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-16 8:51 sashabeton
2026-03-16 11:12 ` Martin Habovštiak
2026-03-16 11:43 ` Alex
2026-03-16 14:36 ` sashabeton [this message]
2026-03-16 15:57 ` Martin Habovštiak
2026-03-16 15:43 ` Alex
2026-03-16 16:00 ` sashabeton
2026-03-16 16:25 ` Martin Habovštiak
2026-03-24 6:02 ` aaron.recompile
2026-03-16 19:29 ` Alex
2026-03-17 7:23 ` Saint Wenhao
2026-03-17 7:40 ` sashabeton
2026-03-17 18:00 ` waxwing/ AdamISZ
2026-03-17 18:30 ` waxwing/ AdamISZ
2026-03-18 5:24 ` Saint Wenhao
2026-03-18 15:50 ` "wrapped Taproot" from RIPEMD-160 collisions, Was: " Ethan Heilman
2026-03-16 11:38 ` Saint Wenhao
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