• #A
    #B
    #C
    #D
    Explanation:
    Validating msg.value early ensures no state mutation occurs before detecting invalid ether transfers. This prevents partially updated storage on failure, preserving atomicity. It aligns with checks-effects-interactions
  • #A
    #B
    #C
    #D
    Explanation:
    Selector collisions occur when different function signatures hash to the same first 4 bytes. This leads to unintended dispatching and silent bugs. It’s especially dangerous in diamond proxies and minimal routers.
  • Application deadline: 4 weeks
    P

    Senior Software Engineer, Frontend

    Phantom FULL_TIMENA

    Job description
    This role focuses on frontend engineering for Phantom’s multi-chain self-custodial crypto wallet. The engineer will be responsible for building and enhancing user-facing features across the Phantom browser extension and website, contributing to UI performance, responsiveness, and quality. The position includes driving product enhancements that expand blockchain support, improving cross-chain usability,...
  • Application deadline: 4 weeks
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    Senior Software Engineer, Full-Stack

    Phantom FULL_TIMENA

    Job description
    This role contributes to the engineering of Phantom’s multi-chain self-custodial wallet, enabling users to interact with crypto assets across Solana, Ethereum, Polygon, and Bitcoin. The position is full-stack, encompassing both user-facing interfaces and backend development, including APIs and service infrastructure that connects blockchain data to frontend experiences. The engineer will...
  • Application deadline: 4 weeks
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    Operations Manager

    P2P.orgFULL_TIMENA

    Job description
    This role supports operational effectiveness and executive coordination within P2P.org’s growing organization. The Operations Manager will assist leadership through structured coordination, logistical execution, and efficient communication across teams. This position involves facilitating strategic sessions, managing executive schedules and requests, and supporting multi-stakeholder projects. The role emphasizes strong organizational skills, ability...
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    Head of Engineering

    P2P.org FULL_TIMENA

    Job description
    This role serves as Deputy CTO and leads engineering efforts for P2P.org’s staking and yield infrastructure. The position oversees development of secure, scalable software services and blockchain-based financial products. The scope includes management of engineering teams, technology strategy, API services, and multi-year platform evolution. The leader in this role will...
  • #A
    #B
    #C
    #D
    Explanation:
    Fallbacks receive raw calldata without predefined structure, forcing developers to manually decode and validate inputs. Any mistake leads to reentrancy or mis-routing. They must be extremely minimal.
  • #A
    #B
    #C
    #D
    Explanation:
    Storage accesses require Merkle-Patricia proof validation at the state level. This makes SLOAD one of the most expensive operations in Solidity. Caching values into memory significantly reduces repeated cost.
  • #A
    #B
    #C
    #D
    Explanation:
    Unbounded loops that depend on storage or user-controlled arrays can exhaust gas and render functions uncallable. Attackers can intentionally cause denial-of-service through loop amplification. Good design avoids external iteration
  • #A
    #B
    #C
    #D
    Explanation:
    String comparison requires hashing or byte-by-byte checks, both of which are expensive in the EVM model. It also introduces risk when mixed with packed encodings. Developers instead rely on enums or hashed IDs.
  • #A
    #B
    #C
    #D
    Explanation:
    Memory follows a quadratic cost function, meaning costs rise rapidly as the memory footprint grows. Careless array allocations can suddenly inflate execution cost. This is a frequent root cause of gas blowups in audits.
  • Shubhada Pande

    Shubhada Pande

    @ShubhadaJP14h

    Smart Contract QA & Testing Hub

    Your central hub for everything related to blockchain QA, including test coverage, CEI testing, flaky tests, mainnet/testnet mismatches, audit support, incident analysis, and how QA engineers grow into blockchain security...
    1
    Replies
  • #A
    #B
    #C
    #D
    Explanation:
    PUSH0 provides a zero literal without consuming calldata or memory. This reduces bytecode size and simplifies stack management. It's extremely helpful in tight loops and assembly-heavy contracts.
  • #A
    #B
    #C
    #D
    Explanation:
    State shadowing happens when a derived contract redeclares a state variable with the same name as a parent. This creates storage misalignment and unexpected slot overwrites. Auditors treat this as a major upgradeability and correctness risk.
  • #A
    #B
    #C
    #D
    Explanation:
    Calldata avoids copying user inputs into memory, significantly reducing gas usage for large payloads. Router contracts receive untrusted inputs, so avoiding memory expansion is both cheaper and safer. This is why AMMs and DEX routers heavily rely on calldata
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