Questions tagged [musig]

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What's cheaper, musig or multisig?

Taproot txs aren't always cheaper onchain compared to their segwit native counterparts. How does the current MuSig spec fair vs multisig onchain? Is one always cheaper than the other wrt number of ...
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0 votes
1 answer
64 views

To what extent does BIP32 key derivation impact the design of secure key aggregation multisig and threshold schemes like MuSig and FROST?

I have seen it discussed in various places (e.g. 1, 2) that using BIP32 key derivation impacts the design of secure key aggregation multisig and threshold schemes like MuSig(2) and FROST. What are the ...
0 votes
0 answers
17 views

What is the argument for not using proofs of possession in Bitcoin multisig and threshold key aggregation schemes?

A number of multisig and threshold sig key aggregation schemes developed outside of the Bitcoin ecosystem (e.g. SpeedyMuSig, FROST) use proofs of possession yet those developed in the Bitcoin ...
1 vote
1 answer
36 views

What's not standard in these descriptors?

In here, about these (indentation is mine): sh(wsh(multi(2, abcdef01/1'/1'/0/*, 23456789/1'/1'/0/*)))#abcdefgh sh(wsh(multi(2, abcdef01/1'/1'/1/*, 23456789/1'/1'/1/*)))#ijklmnop wsh(multi(2, ...
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3 votes
1 answer
124 views

musig2 with BIP-32 style nonce chain

I am interested in the case where a fixed pool of signers will sign a series of many messages. As I understand it, musig2 would allow pre-processing, whereby a signature aggregator could collect a ...
0 votes
1 answer
30 views

Why does only one of the two nonce points in MuSig2 have the exponent b?

In MuSig2 R''_i is added to itself b times (in multiplicative notation, it has the exponent b) but R'_i is not (it does not have the exponent b). Why does only one of the nonce points have the ...
0 votes
1 answer
65 views

In MuSig2 how is multiplication of coordinates defined?

In the MuSig2 paper each signer multiplies all the nonces together (in the naive version): R_1 * R_2 * R_3 * .... R_n where R_i = r_i * G. r_i is a scalar and G is the generator point (coordinate) ...
0 votes
2 answers
130 views

How does SpeedyMuSig compare to MuSig2?

This paper (Crites, Komlo, Maller) on the security of Schnorr multisig and threshold signature schemes introduces a new variant of MuSig2 called SpeedyMuSig that includes proofs of possession and ...
0 votes
1 answer
172 views

How do MuSig2 and FROST compare for multisig key aggregation schemes?

Although FROST is primarily for threshold (k-of-n, k<n) key aggregation schemes (and MuSig2 doesn't support threshold) FROST can support multisig (n-of-n) key aggregation. So what are the upsides ...
3 votes
1 answer
55 views

How do the various Lightning implementations treat latency? How long do they wait for a peer to provide a signature before using unhappy path?

Rene Pickhardt brought up the problem of latency on the Lightning Network in this answer on using nested (or "recursive") MuSig2 or FROST when providing a signature within an existing ...
2 votes
2 answers
138 views

Can you do P2WSH / P2SH on Lightning Network (LN)?

I understand that a channel is a 2 of 2 multisig: 1 && 1 Is it possible that one side of this channel is a multisig wallet? So in essence one of the 2 main, is actually a 2 of 3 multisig. ...
1 vote
1 answer
101 views

With MuSig2 can we now avoid any privacy leak of a Lightning channel's onchain UTXO?

Now we have access to Schnorr and MuSig(2) onchain can we avoid any privacy leak of a Lightning channel's associated onchain UTXO?
2 votes
1 answer
110 views

Where can I get some MuSig2 test vectors?

I am writing a MuSig2 library and need some test vectors. This should include the hash functions used.
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2 votes
1 answer
156 views

How to spend a taproot output using key path with a threshold signature scheme when the secret key is never computed?

In taproot, in order to spend the keypath, the transaction must be signed using the tweaked private key instead of the normal private key (as defined in BIP 341). However when computing a signature ...
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7 votes
1 answer
260 views

Possible number of signers with MuSig

With multisig, up to 20 signatures may be used in a threshold signature scheme (What are the limits of m and n in m-of-n multisig addresses?). As far as I understand, there should be no hard-coded ...
1 vote
1 answer
339 views

Taproot, potential quantum bug, and general clarification

Here seeking information. I have 2 questions marked with parens Would like some clarification pertaining to the Mark Friedenbach article: Why I'm Against Taproot The point of contention with Mark ...
6 votes
1 answer
470 views

What is the difference between key aggregation and signature aggregation?

What is the difference between key aggregation (e.g. MuSig) and signature aggregation? Many people (including myself) have in the past used these terms interchangeably. Why is it important to be ...
2 votes
1 answer
148 views

Using key aggregation (multsig) in P2TR script path spends

I know that it is possible to create a 2-2 multsig using Taproot by combining both private keys into one public key and defining that as the key path spend. I also know that it is possible to use ...
2 votes
1 answer
151 views

Why is Public Key aggregation in MuSig described as a product of the public keys?

In the the MuSig2 paper, it is described that: Each signer randomly generates and communicates to others a nonce Ri=g^ri; then, each of them computes R=∏ni=1Ri,c=H( ̃X,R,m)where ̃X=∏ni=1Xiis the ...
2 votes
1 answer
79 views

In MuSig-DN why not use a truly random number for the nonce instead of a pseudorandom function?

In MuSig-DN why not use a truly random number for the nonce instead of a pseudorandom function (PRF)? If the nonce space is big enough it would never be reused. This question was asked by emzy on ...
2 votes
1 answer
117 views

Who will the first adopters of Taproot be (assuming it is activated at some stage)? What incentives are there to start using it straight away?

Adoption of SegWit by users and companies after it was activated was slow. Should we expect adoption of Taproot to be slow also (assuming it is activated at some stage)? Who will the first adopters of ...
3 votes
1 answer
159 views

Which MuSig scheme is optimal? Classic MuSig or this new MuSig-DN scheme?

Now we have two competing MuSig schemes which is better? Classic MuSig or MuSig-DN? Which use case(s) might choose classic MuSig over MuSig-DN and vice versa?
0 votes
1 answer
78 views

Schnorr without R in the challenge

I read the Schnorr and MuSig papers and stumbled over the problem that the use of deterministic nonces in multisignatures is not safe. The adversary would be able to extract the private key from the ...
3 votes
1 answer
95 views

Is Z-man's PTLC construction implementable using libsecp256k1-zkp?

In a mailing list post Z-man details a PTLC construction which he claims is "is almost entirely a MuSig ritual". My question is whether this MusigTweak is what is called the adaptor (last argument of ...
14 votes
1 answer
675 views

Musig Signature Interactivity

2 Questions: Why is Musig signing always interactive? Let's say I have a Musig wallet where keys are stored in secure locations with no internet access. What are some methods to sign from these ...
10 votes
2 answers
1k views

How could Schnorr signatures be aggregated across the whole transaction?

I am studying the MuSig protocol and am having trouble grasping certain segments. This is my understanding thus far: In current Bitcoin CHECKMULTISIG format, the size of the signature grows linearly ...
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6 votes
1 answer
271 views

Does MuSig have the same security as 2-2 multisig?

Disclaimer: This question is of theoretical importance to me trying to educate myself better on cryptographic principles and signature schemes. I don't intend to imply that in practice schnorr ...
1 vote
1 answer
172 views

Can R/r in Musig be derived from only seeds and message hashes?

I am wondering if the first two roundtrips of pre-committing and then revealing R/r in MuSig signing can be moved to the keygen phase and made deterministic. That reduces the amount of messages that ...