Re: Multisignature address : This was interesting about the uses for different signature combination and wither it is possible to make multi-signature addresses “by hand” …
Enter multisig (short for multi-signature), a lock that only opens with enough keys, out of a set of predefined keys. Let’s say that Alice, Bob and Charlie all want to open a business together and invest some of their money. But none of them actually want only one person to have the private keys to this money. So they each get one key and use a multisig wallet that requires two out of three of those keys. This way none of them can run away with the money alone, but they also don’t need all three of them to pay an expense. For example, if Alice wants to run with the money, she can’t because she only has one key. But if Bob is missing and Alice and Charlie want to pay an expense, they can do it with their two keys (out of the three).
Multisig doesn’t have to be two out of three – it can be almost any combination. Let’s think of a few combinations and some examples of how to use them.
1 of 2: A couple wants to have a shared account and they trust each other. They both share the same money while using their own separate wallet.
2 of 2: Two-factor authentication for you money. You keep one key on your computer and another key on your phone. Whenever you want to spend money, you have to use both.
2 of 3: Trustless arbitration/escrow. Someone wants to buy a product from a stranger on the internet, but cannot trust him. The buyer and seller agree on an arbitrator who will help them in case of a dispute. They each get one key out of three, and the buyer sends the money to a two of three address between the three of them. If the product is delivered and there are no issues, the buyer and seller can use their two keys to release the money to the seller. If there is a dispute, the arbitrator help the buyer to get a refund or help the seller to release the funds. For instance, Bitrated.
2 of 3: Safer paper wallets. Instead of having one key with access to all your money, why not make it two? The third key is a backup in case you lose one of the other two. For example, keep one key on your phone, another key where you would keep your paper wallet, and a third key with a trusted family member.
4 of 7: Company board of directors. Suppose a corporation has a board of directors who wish to own the control of the corporation’s reserves, instead of trusting their executive management to handle all their money. The board of directors can decide that a majority vote (four out of seven) should be enough to delegate funds to executive management.
[Ref 1:] https://99bitcoins.com/multisig-a-beginners-guide/
[Ref 2:] https://99bitcoins.com/pgp-encryption-a-beginners-guide/
