> The goal is giving users who are already happy with the P2WPKH model (no script spending, simple single-key payments) the witness efficiency of Schnorr
If you have a DER signature, then it can take from 9 to 73 bytes. In Schnorr signatures, it is set to 64 or 65 bytes.
In practice, you can have 71 bytes without grinding, which means, that by using a CPU to grind r-value and s-value, to shrink it by 4 bytes each, you will get 63 bytes in a DER signature. And that won't reveal your private key to anyone else. It would require around 2^33 operations, so it is doable on CPUs.
Which means, that if you want to have smaller signatures, and you are willing to put some Proof of Work into that, then you will get better results by just staying with P2WPKH. And, as leading zeroes are not pushed in DER signatures, because of BIP-66, and as computing power is getting better and better, your signatures could be smaller in the future, while in Schnorr signatures, you won't have any way to go below 64 bytes.
To clarify the design intent: P2SKH is not a stripped-down Taproot — it is P2WPKH upgraded to Schnorr. The starting point is P2WPKH (compact 20-byte hash commitment, no script path, single-key payments), and the only change is replacing ECDSA with the same Schnorr signature scheme Taproot's key-path uses. That's it.
The goal is giving users who are already happy with the P2WPKH model (no script spending, simple single-key payments) the witness efficiency of Schnorr without forcing them onto a 34-byte output type designed for a richer feature set they don't need.
P2SKH is not quantum-resistant — I fully acknowledge this. Like P2WPKH, it relies on secp256k1 and will need to be migrated once post-quantum schemes are deployed in Bitcoin. But until that happens, it serves the same users as P2WPKH today, just more efficiently. When the time comes, users migrate — the same way P2PKH and P2WPKH users will have to.
On Monday, 16 March 2026 at 16:45:32 UTC+1 Alex wrote:
>
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.
This is not true. Taproot has 2 modes; its key-spend path is 12 bytes more bloated than your solution, yes. but Taproot can "dynamically" chose whether to use the key-spend path or the script-spend path. Your solution fully removes the script spend path, so you're not really optimizing an equally capable solution, you're optimizing for only 1 part of it.
Removing scriptability for 12 bytes could possibly be warranted in some specific cases (I'm sure there are cases), but it's not a fair comparison against Taproot or BIP360. And since we will need quantum upgrade at some point, this upgrade is kind of (in my personal interpretation) doubling down to the part that will eventually break.
Do you have any plan on how one could quantum secure the funds in P2SKH?
måndag 16 mars 2026 kl. 12:57:52 UTC+1 skrev Alex:
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.
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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