Atomic swap

BLS

• PoS - committee(128 validators)
• latest block, safe block: 12 blocks, finalized block: 64 blocks = 64 slot = 2 epoch
• journal: contains **the list of state modifications applied since the last state commit. These are tracked to be able to be reverted in the case of an execution exception or request for reversal.

Tries

• Transactions Flow: 트랜잭션 생성 및 서명 → 서명 검증

  1. EOA: account
     • fields: nonce, balance, storageRoot, codeHash
       • storageRoot: Only C.A. fields 값(state variables)들의 루트값.
       • codeHash: Only C.A.
  2. 생성하는 법
     1. Transfer(EOA→TX→EOA)
     2. Execute smart contract(EOA→TX→CA)
     3. Deploy smart contract
  3. EVM: 트랜잭션 실행
     1. EVM 구조

        • storage: persistent data store(state variables)

          • storage layout: (key: $2^{256}$ slot, value: 한 slot당 32 bytes이하.)

            keccak(slotID): {
              { key: slotID, value: data length },
              { key: hashed slotID, value: data },
              { key: hashed slotID, value: data }
            }
            

            contract StorageExample {
              uint256 public x;                // Slot 0
              uint256[] public dynamicArray;   // Slot 1 (length stored here, elements at keccak256(1))
              mapping(uint256 => uint256) public map; // Hash-based storage
            
              struct MyStruct {
                uint128 a;
                uint128 b;
                uint256 c;
              }
            
              MyStruct public s;             // Starts at Slot 2
            }
            

        • memory: temporary data store(function parameters, local variables)

        • stack: opcode operation

        • calldata: read-only data

     2. 실행 후: world state 변경(status: pending)
  4. Broadcast pending txs to mempool of validator
     1. 어떻게 broadcast??: P2P network의 wire protocol을 이용
     2. P2P network 형성
        1. UDP: bootnodes(detect and discover new nodes)와 PING-PONG
        2. TCP: RLPx protocol(establish connection for communication and encrypt message)
        3. TCP: Wire protocol(propagate pending transactions, blocks and synchronize states)
  5. Create and validate a block
     1. pending transaction을 포함하고, 블록을 검증 완료(status: success)
     2. validator는 누가?? PoS는 32ETH이상
  6. Propagate a block

• Log

  • LogsBloom: 블록 히스토리를 효율적으로 찾기위한 인덱싱 값.
  • Solidity Events: logsBloom 프로퍼티에 저장되는 값 매칭
  • Log Object
    • data: indexed가 아닌 인자값
    • topics: 1번째: 이벤트 서명 해시(e.g., keccak256(‘이벤트이름(파라미터타입)’)), 2번째~5번째: indexed인 인자값
  • Bloomfilter
    • 특정 원소가 집합에 속했는지 검사하는 확률형 자료 구조

• ECDSA

  Signing

  • Input: Random Integer, Hashed message, private key

  • Output: Signature (R, S)

  Verifying

  • Input: Signature (R, S), Hashed message, public key

  • Output: Valid or Invalid

  • Elliptic Curve Cryptography(ECC) Public key

    • compressed and uncompressed?

      ECC -> prefix 04(uncompressed) => 65 bytes

      -> prefix 02(compressed): y is even. => 33 bytes

      -> prefix 03(same as above): y is odd.

    • why compress?

      two times less space in memory by removing the y coordinate

• Kademlia: Node discovery

• RLP(Recursive Length Prefix), Serialization, RLPx: Data Exchange Protocol

  이더리움 네트워크에서 노드에 데이터 저장 or 통신에 통일된 형식이 필요, Data format.

  • why?
  • how 통일된 형식? -> serialization이라고 부르고 이를 통해 만들어진 형식을 "byte stream" 이라고 함
  • 이더리움에서 쓰이는 serialization이 "RLP(Recursive Length Prefix)" 참고: https://ethereum.github.io/yellowpaper/paper.pdf#page=19

• Pruning

  • Problem: eliminating or cleaning obsolete historical data to optimize disk space.

  • How it works

  1. Iterating state snapshot

  2. Pruning state data: from the database

  3. Compacting database