# btc-address-scripting-mechanism

## Purpose

This doc describes the required changes to Bitcoin multisignature wallet scripting mechanism (previously described in Multisignature wallet LLD).

## Scope

TODO

## Process Overview

SONs are expected to be co-signatories for the funds stored on PW. Each SON has a public key on Bitcoin (secp256k1) and the weight of its signature.

This is executed on Bitcoin blockchain with the following script:

\<pubkey1> OP\_CHECKSIG

OP\_IF

\<voting\_weight1>

OP\_ELSE

0

OP\_ENDIF

OP\_SWAP

\<pubkey2> OP\_CHECKSIG

OP\_IF

\<voting\_weight2>

OP\_ADD

OP\_ENDIF

...

OP\_SWAP

\<pubkeyN-1> OP\_CHECKSIG

OP\_IF

\<voting\_weightN-1>

OP\_ADD

OP\_ENDIF

OP\_SWAP

\<pubkeyN> OP\_CHECKSIG

OP\_IF

\<voting\_weightN>

OP\_ADD

OP\_ENDIF

\<two\_thirds\_of\_total\_voting\_weight>

OP\_GREATERTHAN

The point of the script is that each SON has a weight (sum of votes for SON that is set at maintenance). Depending on the cumulative weight of votes a decision is made on whether the transfer is to be executed. For the transfer to happen the sum of weights in the script must be >= 2/3 + 1 from the number of current active SON weights.

Since the addresses depend on weights, and weights in turn depend on balances, on most occasions the deposit addresses will be re-generated after maintenance. There are two ways to handle this situation:

1. All pre-maintenance are to be considered invalid after maintenance.
2. Consider the pre-maintenance composition of SONs and their weights trusted post-maintenance. If the composition of SONs doesn't change, but their weights do, SON members are to be allowed to process the transaction in accordance with their pre-maintenance weights.

We can change the ranking upon the first transaction related to PW/SONs takes place. This is further discussed here : [Functional Specification - SONs switchover scenarios#SONsswitchoverscenarios-6.Scenarios](https://peerplays.atlassian.net/wiki/spaces/PIX/pages/307003405/Functional+Specification+-+SONs+switchover+scenarios#FunctionalSpecification-SONsswitchoverscenarios-SONsswitchoverscenarios-6.Scenarios)


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