Ask HN: Is an immutable ledger (DAG) necessary for a (e-)coin?

2 points by patientplatypus 7y ago ↗ HN

So, I may not necessarily understand this, but why is an immutable hash ledger that always grows necessary for an e-coin? It would seem that out of the box these coins have limited lifetime as hard drive space and computational time are finite.

Is there an alternative to simply storing the entire hash history, while still making an e-coin secure?

2 comments

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fiiv 7y ago ↗

Speaking in what's out there now, there is Nano that only requires latest data (latest block) to participate in consensus (called a Current Node). I know that doesn't answer your more broad question of if its necessary but thought I'd point that out.

It would mean that nodes can store only some of the ledger. Even in the case of a node storing historical data not directly connected to the current block, such a node would only need to get the last block (and not the in-between ones) in order to jump back into consensus (someone please correct me if I'm wrong on this).

wmf 7y ago ↗

There are various forms of pruning that allow storing only the current state, although in some cases that state may also grow without bound.