[_8j50]

The one thing I am curious about is the idea of reputation establishment. Has there been any attempt to reduce impact of a sybil attack by introducing reputation metrics?

What if for example with SCP quorum slices form only between nodes of agreeable reputation where reputation could either be transaction confirmation history or transaction participation history or some combination of both.

I would argue,if some form f reputation metric was in play,a simple 51% majority (for unfederated) would not mean much,especially if each node gets to unilaterally decide reputation metrics it finds agreeable which will make it hard for a sybil attacker to know how many nodes of what reputation it needa to control to succeed.where a failed sybil attack could reduce or eliminate reputation of the nodes it used.

The whole idea is so simple I feel a bit cluelees even asking about it,but does anyone know if similar consensus systems have been explored?

[mazieres]

The thing is that reputation isn't formed in a vacuum. E.g., in the case of Stellar's blockchain, you have companies issuing assets like digital dollars or carbon credits or shares in commercial real estate ventures. The tokens have value because people trust their counterparties. Even in the case of XLM, Stellar's "native" cryptocurrency, ultimately people believe it has value because they can trade it for other assets on Stellar's built-in DEX or sell it for fiat currency or other crypto at exchanges. It doesn't matter how many Sybil nodes an attacker creates, if I place Kraken and Coinbase in my quorum slice, I will remain in sync with their validators and know that I can subsequently choose to deposit all of my tokens on those exchanges for trading.