Bitcoin and Ethereum developers are pursuing different protections against possible quantum computing attacks. As of October 22, 2026, neither network offered existing holders a standard wallet option that replaces today's transaction signatures. The two blockchains differ, however, in what developers can test without changing network rules.
Bitcoin's BIP-360 proposes an output type called Pay-to-Merkle-Root, or P2MR. It would remove Taproot's direct key-spending option and require holders to spend through scripts stored in a cryptographic tree.
The change targets public keys that remain exposed on the blockchain. Researchers have warned that a sufficiently powerful quantum computer could potentially use such keys to calculate private keys. But BIP-360 makes a narrow claim. Its authors say the proposal “does not include the introduction of post-quantum signature schemes.”
The draft leaves another problem unresolved. When a holder broadcasts a transaction, a public key can become visible before miners confirm it. Protecting against an attack during that window would require further work. Bitcoin would need to adopt P2MR through a soft fork before wallets could use it on the main network.
Another research effort, SHRINCS, focuses on the signatures themselves. Developers published a draft in August describing a hash-based method for authorizing Bitcoin transactions. Unlike P2MR, it addresses how a holder proves the right to spend coins.
However, a published design is not an activated Bitcoin feature. SHRINCS still needs review, testing and a route into the network's spending rules. Neither proposal changes how existing coins are protected.
The released Bitcoin Core wallet continues to support established address formats, including SegWit and Taproot. Version 31.1 brought fixes rather than support for P2MR or post-quantum signatures. Holders therefore cannot choose either proposal as a normal wallet setting.
Ethereum developers have a different starting point. Smart contracts can already check signatures through custom code, which allows research teams to test alternative methods without first changing the main network's transaction format.
The SPHINCS- project has developed post-quantum signature verifiers for Ethereum. Its documentation covers Sepolia tests and separate experiments on an ethrex test network. The developers caution that the unaudited software is “not safe to use with real funds.” A successful test does not mean ordinary wallets can safely use the feature.
Meanwhile, EIP-8141 proposes a new transaction format that would let account code handle authorization and fee payments. The proposal remains a draft. Ethereum has not activated these frame transactions on its main network.
For existing externally owned accounts, adding smart-contract verification does not automatically remove the authority of the original private key. Under EIP-7702, that key can authorize changes to an account's delegated code or clear the delegation entirely.
An account could consequently check a post-quantum signature while its original key still retains a way to control the account. A complete migration must address that remaining access and give users wallet software that can manage the new signing method.
Hardware makers have begun their own work. Ledger has described ML-DSA signing support in its developer kit. However, creating a signature on a device does not mean either blockchain accepts that signature for payments. Network rules, wallet support and recovery tools remain distinct requirements.
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