Bitcoin and inheritance, a House of the Dragon story

House of the Dragon is an American fantasy drama television series. A prequel to Game of Thrones (2011–2019), it is the second show in the franchise, created by George R. R. Martin and Ryan Condal for HBO. Beware, this article contains spoilers.

Nobody is safe in the realm of the Seven Kingdom, known for the brutality and the trickery of its subjects. Seated on the Iron Throne, King Viserys I Targaryen must handle the burden of the crown and the tumultuous behavior of his brother, the Rogue Prince, Daemon Targaryen. The Targaryens are the most powerful family of Westeros, the continent they conquered with the fire of their dragons and their knowledge of the dark arcane of Bitcoin.

As usual in the Game of the Thrones, our story begins with a death. The Queen consort, Aemma Arryn dies without giving birth to a male offspring. The King is incited by his advisors to declare his Heir to assure that the royal line is clear to all. Irritated by Daemon provocations, The King chooses his daughter Rhaenyra instead despite the old misogynistic tradition.

Protecting the realm funds

Securing the fabulous treasure of the family is not an easy task, but thanks to Bitcoin and cryptography the Targaryens do not have to enchain one of their dragons on top of a mountain of Gold anymore. Each Targaryen is educated from their young age to generate, secure and hide (Sometimes between the scales of their own dragons) cryptographic keys.

The Old King, Jaehaerys I Targaryen, did a secret ceremony with his grand son Viserys after choosing him as his Heir. They setted up a simple 1 of 2 multisig and locked the family legacy in new Bitcoin outputs. At this time, Viserys was a grown adult, married and aware of the responsibilities to come.

                            │
                            │
                    ┌───────┴───────┐
                    │     1 of 2    │

               Jaehaerys         Viserys

The resulting miniscript descriptor:

wsh(multi(1,<Jaehaerys xpub>,<Viserys xpub>))

A simple Inheritance Plan

Rhaenyra is still young and Viserys is afraid of her adventurous nature, She is the Heir but as long as Viserys is alive, He prefers to keep the key of the treasure himself. But what if something happens to him ? Rhaenyra must be able to somehow get control of the funds.

During a secret ceremony in front of the old skull of Balerion the Black Dread, Viserys creates a new descriptor and shares it to his daughter, then moves the funds to outputs with scripts derived from it.

              Viserys

                 │
                 │
                 │
    52600 blocks │
           older │
                 │
                 │
                 │
                 │

             Rhaenyra

The descriptor rules that only Viserys key can move funds immediatly, but after a fixed number of block passed the key of Rhaenyra also becomes valid. Viserys number of block choice was enough to represent 1 years of wait.

A set of keys that can move the funds at any time is called the primary path, and any other sets of keys paired with a time lock are called recovery paths.

The new miniscript descriptor:

wsh(
  or_d(
    pk(<Viserys xpub>),
    and_v(
      v:pkh(<Rhaenyra xpub>),
      older(52600)
    )
  )
)

The King with his new wallet with inheritance included have full disposal of his funds but in case of premature death, funds will be spendable in 1 years maximum by Rhaenyra. King Viserys must move coins to new outputs before the sequence runs out, either passively by his ministerial usage of the wallet with change outputs or pro-actively by doing a transaction to himself like outputs consolidation.

A complex family

Viserys gets married a second time with the daughter of the Hand of the King: Alicent. She gives him two sons: Aegon and Aemond targaryens. Rumors spread to the country that Aegon should be the new Heir, but Viserys does not change the succession order. Sick by a mysterious illness and advised by his ministers, Viserys wants to include the whole succession line in the bitcoin scripts locking the realm’s treasure.

               Viserys

                  │
                  ├──────────────────┐
                  │                  │
     52600 blocks │     65000 blocks │
            older │            older │
                  │                  │
                                     │
              Rhaenyra               │
                                     │

                                   Aegon

An inheritance plan can include multiple recovery paths, each of them becoming valid at different locking times. As the script grows, miniscript helps the targaryens to handle the new complexity:

wsh(
  or_i(
    and_v(
      v:pkh(<Aegon xpub>),
      older(65000)
    ),
    or_d(
      pk(<Viserys xpub>),
      and_v(
        v:pkh(<Rhaenyra xpub>),
        older(52600)
      )
    )
  )
)

A deterrent against assassination.

Rhaenyra is furious against her father. She confronts him and makes him aware that she will be at risk of being assassinated between the time Viserys dies of his sickness and the expiration of the sequence of block disallowing her to move the funds. She wants for Daemon, her uncle, a fierce warrior and loyal friend, to hold a key along with Aegon key. Rhaenyra is confident that in case she get murdered, Daemon will lock the funds and will take no rest until her murderers are hanged on the King’s Landing main place.

               Viserys

                  │
                  ├──────────────────┐
                  │                  │
     52600 blocks │     65000 blocks │
            older │            older │
                  │                  │
                                     │
              Rhaenyra               │
                                     │
                            ┌────────┴─────────┐
                            │      2 of 2      │

                          Aegon             Daemon
wsh(
  or_i(
    and_v(
      v:thresh(2,pkh(<Aegon xpub>),a:pkh(<Daemon xpub>)),
      older(65000)
    ),
    or_d(
      pk(<Viserys xpub>),
      and_v(
        v:pkh(<Rhaenyra xpub>),
        older(52600)
      )
    )
  )
)

A dispute resolution

Viserys wants to accept Rhaenyra solution but he knows too well the explosive temperament of his brother and the ambition that any Targaryen carries with him. Aegon is young and does not seems interested in politics, Daemon could leverage his position to keep funds in hostage by not collaborating and gain enormous power over the royal court.

As Viserys agony starts to be extremely painful, he starts having visions and his religious faith makes him believe that including the grand maester may be a good idea. He then adds a third recovery path with the clerical power as a third party, that will be in charge of dispute resolution between Aegon and Daemon.

           Viserys

              │
              ├──────────────────┬────────────────────┐
              │                  │                    │
 52600 blocks │     65000 blocks │       65535 blocks │
        older │            older │              older │
              │                  │                    │
                                 │                    │
          Rhaenyra               │                    │
                                 │                    │
                        ┌────────┴─────────┐          │
                        │      2 of 2      │          │
                                                      │
                      Aegon             Daemon        │
                                                      │
                                                      │ 2 of 3
                                            ┌─────────┼───────────┐
                                            │         │           │

                                        Aegon       Daemon      Maester

Institutions and entreprise may use the same idea for their funds. Instead of a decaying multisig with a threshold decreasing over time, new third parties like insurance company or notary agencies are added to the policy. The threshold can be increased to prevent malicious collaboration at the path scope but the minimal number of key required for an attacker to retrieve the funds will always stay related to the general scope according to the “weakest” path.

Behold the final descriptor of the royal family:

wsh(
  or_i(
    and_v(
      v:thresh(3,pkh(<Aegon xpub>),a:pkh(<Daemon xpub>),a:pkh(<Maester xpub>)),
      older(65535)
    ),
    or_i(
      and_v(
        v:thresh(2,pkh(<Aegon xpub>),a:pkh(<Daemon xpub>)),
        older(65000)
      ),
      or_d(
        pk(<Viserys xpub>),
        and_v(
          v:pkh(<Rhaenyra xpub>),
          older(52600)
        )
      )
    )
  )
)

The end of our story

Blinded by hate and biases, the Greens, Alicent family, prefer war and the risk of loss of the realm funds than letting Rhaenyra sit on the throne. During the weeks the old King Viserys died, a race begins between them and the Blacks, Rhaenyra clan, to rally allies and gather troops while Aegon is proclaimed King.

Dear reader, pity the poor citizen of Westeros as they will suffer yet another war from the powerfuls as a new peril from North is marching upon them. For thousands of year, they live under a feudal system where basics rights differs according to bloodline and nobility. May they discover the secret power of the Targaryens and free themselves from any crown by using an allodial money.


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