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Implement conversion from Long-encoded nBits representation to BigInt and back #675

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kushti opened this issue Jul 30, 2020 · 4 comments
Open

Implement conversion from Long-encoded nBits representation to BigInt and back #675

kushti opened this issue Jul 30, 2020 · 4 comments
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A-consensus Area: Code used in consensus (i.e. transaction validation) Bounty - 200 SigUSD C-feature Category: Feature request or PR P2-medium Priority: Medium soft-fork Implementation requires soft-fork
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v6.0

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@kushti
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kushti commented Jul 30, 2020

For trustless mining derivatives (see e.g. this proposal https://www.ergoforum.org/t/mining-power-derivatives-two-tokens-approach/277 ) it could be good to have difficulty encoded as a big integer, but currently it is represented in nBits format (as Long value) in the context, which is not suitable for comparisons.

Thus it would be reasonable to implement fromNBits operation, converting nBits in Long value to BigInt.

nBits encoding implementation and corresponding test vectors can be found in the Ergo node codebase.
@kushti kushti added the hard-fork Implementation requires hard-fork label Jul 30, 2020
@kushti kushti added this to the v4.0 milestone Jul 30, 2020
@aslesarenko
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@kushti Is it AutolykosPowScheme.getB method you are referring to?

@aslesarenko aslesarenko added A-consensus Area: Code used in consensus (i.e. transaction validation) C-feature Category: Feature request or PR P2-medium Priority: Medium soft-fork Implementation requires soft-fork and removed hard-fork Implementation requires hard-fork labels Sep 9, 2020
@aslesarenko aslesarenko modified the milestones: v4.0, v4.x, v6.0, v5.0 Sep 9, 2020
@aslesarenko aslesarenko added the 4h Approximately 4 hours of work label Sep 11, 2020
@aslesarenko aslesarenko changed the title Implement conversion from Long-encoded nBits representation of a big number to BigInt Implement conversion from Long-encoded nBits representation to BigInt Sep 11, 2020
@aslesarenko aslesarenko modified the milestones: v5.0, v6.0 Apr 4, 2021
@kushti
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kushti commented Dec 23, 2022

@aslesarenko https://bitcoin.stackexchange.com/questions/57184/what-does-the-nbits-value-represent

@kushti
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kushti commented Dec 23, 2022

@aslesarenko In the reference client code, nbits <-> bigint conversion done in RequiredDifficulty.encodeCompactBits / RequiredDifficulty.decodeCompactBits

@kushti kushti changed the title Implement conversion from Long-encoded nBits representation to BigInt Implement conversion from Long-encoded nBits representation to BigInt and back Mar 29, 2024
@kushti kushti mentioned this issue Apr 10, 2024
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@kushti kushti added Bounty - 200 SigUSD and removed 4h Approximately 4 hours of work labels Apr 15, 2024
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kushti commented Apr 15, 2024

Encoding done in #962

The bounty assigned for decoding part (which would be a dedicated PR)

@aslesarenko aslesarenko removed their assignment May 12, 2024
@SethDusek SethDusek mentioned this issue Sep 17, 2024
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A-consensus Area: Code used in consensus (i.e. transaction validation) Bounty - 200 SigUSD C-feature Category: Feature request or PR P2-medium Priority: Medium soft-fork Implementation requires soft-fork
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