Do multisig addresses share the same space as regular addresses and produce the same types of keys?

Question

Let me word it another way. Can a normal Monero seed produce the same address as a multisig wallet? And, if so, would that mean that the private spend key generated by that wallet would be able to spend the outputs of what would otherwise be a wallet requiring >1 signature?

To take it a step further (or possibly restate the same question in a different way), can a multisig wallet produce a single seed that allows the wallet to be created, along with master private keys for that address? Hopefully the way a multisig wallet is constructed, it would preclude the "reverse engineering" of a seed.

Answer 1

Multisig addresses are like any other address generated from independent spendkey and viewkey. In fact, there exists some spendkey which lets you spend from it alone, but nobody knows which one of all the possibilites it is. Same like nobody can tell a spendkey of a regular wallet.

Can a normal Monero seed produce the same address as a multisig wallet?

Probably no. That's because the view key is not derived from the spend key.

For the second part of your question, it's possible to create such a wallet. Not by using the seed, but by using the keys.

For N/N, it's as simple as taking the same viewkey, and adding the individual spendkeys together and using the result as the spendkey of this "master" wallet. Of course, you need all the spend keys for N/N.

The "master" wallet will be no different than any other wallet created by using --generate-from-keys option. All you need to do is compute the EC sum of individual keys and use the result for the spendkey.

In fact, PR-2218 makes a command-line option to do the above.