Multi-signature Bitcoin wallets are not inherently more resistant to quantum computers compared to single-signature wallets. The resistance to quantum computers depends on the underlying cryptographic algorithms used in the wallet.
The security of Bitcoin wallets relies on cryptographic primitives, such as digital signatures, which are vulnerable to attacks from quantum computers.
"No, ECDSA and EC-Schnorr, as well as related schemes like EdDSA, all belong to the class of elliptic curve cryptography. Their security is based on the assumption that the EC discrete logarithm is unfeasibly hard to compute. This assumption is not true if a sufficiently strong general-purpose quantum computer would exist." [1]
Quantum-resistant signature algorithms do exist, but they often come with larger signature sizes, which may make them impractical for use in Bitcoin.
"Quantum resistant signature algorithms do exist, but they all rely on very large signatures - which may make them unfeasibly expensive for purposes like Bitcoin." [1]
The migration to quantum-resistant cryptography will be a slow process, and it requires users to proactively upgrade their wallets.
"The process of migrating wallets and certificates to quantum-resistant crypto will be a painfully slow one, as any new standard adoption in security." [0]
The public key associated with a Bitcoin wallet is not actually exposed in modern Bitcoin addresses, only the hash of it. This limits the capabilities of an attacker using quantum computers.
"The real reason why (most) of Bitcoin transactions are not (much) threatened by quantum computers is that in modern Bitcoin addresses the public key connected to the wallet is not actually exposed (so, not really public), only the hash of it, which limits a lot the capabilities of an attacker." [0]
There are ongoing efforts to develop quantum-resistant blockchains and related applications, but it is not a straightforward process.
"There is ongoing work to design quantum-resistant blockchains and related applications, it's certainly feasible, but it's not as straightforward as the guy puts it." [0]
