Users have one or more Ethereum accounts, wallets, etc. that they care about, including the full history of transactions. Let’s call this a Portfolio.
As per the discussion on data/infrastructure it’s quite difficult to query/parse this information today.
By making it so that users can make their data portable, it also makes it easier for dApps to immediately add value by easily importing the users portfolio.
Store on IPFS / blockchain
Could there be a Portfolio Portability smart contract that stores an IPFS link along with an Ethereum address?
A user can go to a dApp that supports Portfolio Portability (this might be part of the initial open source build) which does a query on their addresses and stores all past transactions. A backup is created and placed on IPFS, and that IPFS link is written into the PP smart contract.
For import, on sign in, users validate the ownership of their Portfolio “key” address by signing. Once the address is validated, the system can then look up the IPFS hash associated with that key address, and import past transactions.
Various validations can be done to verify that this is correct – the source data remains on the blockchain, this is like caching a query on a per user basis.