Historical block hash as part of the L1Block contract

zhivkoto - No Role
June 7, 2023, 9:24 a.m.

Hi guys, Z from LimeChain. TLDR Over the past 2 months we’ve encountered two use cases that are almost possible with the Bedrock update but not quite - both related to the L 1 block hash part of the L 1 Block contract. We think that solving this problem would be valuable for the developer community. This post aims to outline two use-cases that call for the existence of historical L 1 block hash as part of the L 1 Block. Use case # 1 : Cross-rollup communication One popular approach of the notoriously hard field of cross-rollup communication offers is proving that State X (represented in Storage A) has a certain value in another rollup. This happens by proxy of the L 1 state. For any L 1 Block where the source rollup has already anchored a certain value in a storage slot, a prover can prove inside Optimism that the value exists and is exactly that. The L 1 Block contract nicely offers the block hash of the latest L 1 block and this allows access to the state tree root. This is enough to run trustless Merkle-Patricia Trie (MPT) verification of the source rollup storage slot value. While in theory, this is correct, in practice any prover has just 15 seconds time window to gather all the necessary information and submit OP transaction - in 15 seconds the block hash present in the L 1 Block will change and the MPT will no longer be correct. If there was a historical mapping of L 1 block number to block hash (both of those are present in the L 1 Block at a certain time) the use-case would be practical as anyone can prove against any historical block. Use Case # 2 : Proving Transactions or Receipts In somewhat similar vain to the cross rollup communication via storage slot proofs, we can find another use-case - proving that a certain transaction happened inside L 1 , either by proving the transaction and its data, or its receipt. While in use case # 1 , you can at least recalculate your MPT proof for the new block hash, in this use-case once your targeted block hash is gone, you no longer can trustlessly prove the transaction or the receipt. Remember that unlike storage that has “memory” passed in the next blocks, transactions and receipts are only stored in their block and not the subsequent ones. This makes these 15 seconds critical, and any infra failure unrecoverable. Solution A: The Ugly Workaround The ugly solution one can create is “pinning” service. Every time the block hash updates, an automated script sends OP transaction that reads and saves the L 1 block hash in a mapping against its L 1 block number. While this is a possible solution, this requires trust in the pinning service liveness, and has the potential for huge wast and somewhat unbounded costs. Solution B: The Neat Solution A neat solution would be for the historical block hashes to be part of the L 1 Block contract - they are already going through it. Instead of replacing them, just store them in a mapping. Any feedback is deeply appreciated. If this discussion garners popularity, the team at LimeChain will be happy to contribute this to the OP stack.

The post discusses two use cases involving the need for historical L1 block hashes as part of the L1 Block contract. The first use case revolves around cross-rollup communication, where having access to historical block hashes would enable practical verification in Merkle-Patricia Trie. The second use case involves proving transactions or receipts, highlighting the importance of historical block hashes for trustless proofs. It proposes both an "ugly workaround" and a "neat solution" to address this issue and invites feedback and contributions from the developer community.

Likes: 4 Replies: 0

Likers: lee0007, thevikk, realgalinganchev, HannahDEVOP

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zhivkoto - No Role
June 7, 2023, 1:24 p.m.

Hi guys, Z from LimeChain. TLDR Over the past 2 months we’ve encountered two use cases that are a… Hi guys, Z from LimeChain. TLDR Over the past 2 months we’ve encountered two use cases that are almost possible with the Bedrock update but not quite - both related to the L 1 block hash part of the L 1 Block contract. We think that solving this problem would be valuable for the developer community. This post aims to outline two use-cases that call for the existence of historical L 1 block hash as part of the L 1 Block. Use case # 1 : Cross-rollup communication One popular approach of the notoriously hard field of cross-rollup communication offers is proving that State X (represented in Storage A) has a certain value in another rollup. This happens by proxy of the L 1 state. For any L 1 Block where the source rollup has already anchored a certain value in a storage slot, a prover can prove inside Optimism that the value exists and is exactly that. The L 1 Block contract nicely offers the block hash of the latest L 1 block and this allows access to the state tree root. This is enough to run trustless Merkle-Patricia Trie (MPT) verification of the source rollup storage slot value. While in theory, this is correct, in practice any prover has just 15 seconds time window to gather all the necessary information and submit OP transaction - in 15 seconds the block hash present in the L 1 Block will change and the MPT will no longer be correct. If there was a historical mapping of L 1 block number to block hash (both of those are present in the L 1 Block at a certain time) the use-case would be practical as anyone can prove against any historical block. Use Case # 2 : Proving Transactions or Receipts In somewhat similar vain to the cross rollup communication via storage slot proofs, we can find another use-case - proving that a certain transaction happened inside L 1 , either by proving the transaction and its data, or its receipt. While in use case # 1 , you can at least recalculate your MPT proof for the new block hash, in this use-case once your targeted block hash is gone, you no longer can trustlessly prove the transaction or the receipt. Remember that unlike storage that has “memory” passed in the next blocks, transactions and receipts are only stored in their block and not the subsequent ones. This makes these 15 seconds critical, and any infra failure unrecoverable. Solution A: The Ugly Workaround The ugly solution one can create is “pinning” service. Every time the block hash updates, an automated script sends OP transaction that reads and saves the L 1 block hash in a mapping against its L 1 block number. While this is a possible solution, this requires trust in the pinning service liveness, and has the potential for huge wast and somewhat unbounded costs. Solution B: The Neat Solution A neat solution would be for the historical block hashes to be part of the L 1 Block contract - they are already going through it. Instead of replacing them, just store them in a mapping. Any feedback is deeply appreciated. If this discussion garners popularity, the team at LimeChain will be happy to contribute this to the OP stack.

Likes: 4 Replies: 0

Likers: lee0007, thevikk, realgalinganchev, hannahdevop

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lee0007 - No Role
June 7, 2023, 8:43 p.m.

Your proposal could align well with Collective Intent # 1 Techincal Decentralisation [OLD] Col… Your proposal could align well with Collective Intent # 1 Techincal Decentralisation [OLD] Collective Intents: Season 4 Delegates ? Collective Intents Season 4 lays the groundwork to align the entire community around Collective Intents. Intents are directional goals that allow the Collective to align and focus. You can think of an Intent as a near term target. There may be multiple paths towards that target; it is up to the Collective to determine which paths to pursue by proposing Missions. Most Season 4 Intents will be set by the Foundation. Future Intents will incorporate more and more input from the community, until the… Also recommend checking out the info on Mission Proposals & Template Token House Missions ARCHIVED & OLD Missions Missions Season 4 aligns the entire community around Collective Intents. All work supported or executed by the Collective should be in pursuit of our Collective Intents. This is a simple concept, but it is distinct from the way work is supported and executed in most DAOs. The Season 4 structure is designed very intentionally, based on our research, to avoid some common challenges faced by other daos. These challenges usually relate to a structure wherein working groups resembling persistent bus… [OLD] Proposed Mission Template Policies and Templates ? Mission Proposal Template We welcome feedback on the below proposal template S 4 Intent: Proposed Mission: Please include a one line description (tl;dr) Proposal Tier: Please verify that you meet the qualifications for submitting at the above Tier: If an Alliance is comprised of individual contributors tiers, the Tier at which that Alliance may submit should be the Tier at which the Alliance Lead qualifies. Baseline grant amount: % of total available Intent Budget: All Mission grants are…

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Likers: HannahDEVOP

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lee0007 - No Role
June 8, 2023, 12:43 a.m.

Your proposal could align well with Collective Intent # 1 Techincal Decentralisation Collectiv… Your proposal could align well with Collective Intent # 1 Techincal Decentralisation Collective Intents Intents Collective Intents Season 4 lays the groundwork to align the entire community around Collective Intents. Intents are directional goals that allow the Collective to align and focus. You can think of an Intent as a near term target. There may be multiple paths towards that target; it is up to the Collective to determine which paths to pursue by proposing Missions. Most Season 4 Intents will be set by the Foundation. Future Intents will incorporate more and more input from the community, until th… Also recommend checking out the info on Mission Proposals & Template Token House Missions ? Mission Proposals Missions Season 4 aligns the entire community around Collective Intents. All work supported or executed by the Collective should be in pursuit of our Collective Intents. This is a simple concept, but it is distinct from the way work is supported and executed in most DAOs. The Season 4 structure is designed very intentionally, based on our research, to avoid some common challenges faced by other daos. These challenges usually relate to a structure wherein working groups resembling persistent bu… Proposed Mission Template ? Policies and Templates Mission Proposal Template We welcome feedback on the below proposal template S 4 Intent: Proposed Mission: Please include a one line description (tl;dr) Proposal Tier: Please verify that you meet the qualifications for submitting at the above Tier: If an Alliance is comprised of individual contributors tiers, the Tier at which that Alliance may submit should be the Tier at which the Alliance Lead qualifies. Baseline grant amount: % of total available Intent Budget: Please check here if …

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Likers: hannahdevop

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lee0007 - No Role
June 8, 2023, 12:43 a.m.

Your proposal could align well with Collective Intent # 1 Techincal Decentralisation [OLD] Col… Your proposal could align well with Collective Intent # 1 Techincal Decentralisation [OLD] Collective Intents: Season 4 ? Token House Governance Collective Intents Season 4 lays the groundwork to align the entire community around Collective Intents. Intents are directional goals that allow the Collective to align and focus. You can think of an Intent as a near term target. There may be multiple paths towards that target; it is up to the Collective to determine which paths to pursue by proposing Missions. Most Season 4 Intents will be set by the Foundation. Future Intents will incorporate more and more input from the community, until the… Also recommend checking out the info on Mission Proposals & Template Token House Missions ARCHIVED Mission Proposals Missions Season 4 aligns the entire community around Collective Intents. All work supported or executed by the Collective should be in pursuit of our Collective Intents. This is a simple concept, but it is distinct from the way work is supported and executed in most DAOs. The Season 4 structure is designed very intentionally, based on our research, to avoid some common challenges faced by other daos. These challenges usually relate to a structure wherein working groups resembling persistent bu… Proposed Mission Template ? Policies and Templates Mission Proposal Template We welcome feedback on the below proposal template S 4 Intent: Proposed Mission: Please include a one line description (tl;dr) Proposal Tier: Please verify that you meet the qualifications for submitting at the above Tier: If an Alliance is comprised of individual contributors tiers, the Tier at which that Alliance may submit should be the Tier at which the Alliance Lead qualifies. Baseline grant amount: % of total available Intent Budget: All Mission grants are…

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Likers: hannahdevop

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zhivkoto - No Role
June 12, 2023, 3:26 a.m.

Hey @lee 0007 , appreciate your input. We’ve went through the guidelines shared and think that a Mi… Hey @lee 0007 , appreciate your input. We’ve went through the guidelines shared and think that a Mission Proposal would indeed be a good fit for that, so we’ll probably explore it.

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Likers: lee0007, HannahDEVOP

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zhivkoto - No Role
June 12, 2023, 7:26 a.m.

Hey @lee 0007 , appreciate your input. We’ve went through the guidelines shared and think that a Mi… Hey @lee 0007 , appreciate your input. We’ve went through the guidelines shared and think that a Mission Proposal would indeed be a good fit for that, so we’ll probably explore it.

Likes: 2 Replies: 0

Likers: lee0007, hannahdevop

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