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Hu Lifan - Project Portfolio Page

Overview

Crypto1010 is a CLI-based blockchain learning application that lets users create wallets, transfer funds, and validate chain integrity locally.
My primary scope was implementation ownership of blockchain/transfer internals plus release hardening through bug triaging and fixes during PE-D.

Summary of Contributions

Code contributed

• Functional code (Repo)

Enhancements implemented

• Implemented and refined the Blockchain/Block subsystem as the single source of truth for:
  • block creation/linkage (previousHash, index continuity)
  • deterministic hash-based integrity checking
  • chain-wide validation semantics (structure, linkage, transaction format, running-balance checks)
• Integrated transfer recording flow so successful send operations append transactions through a controlled model path.
• Strengthened persistence safety by validating loaded blockchain data before accepting it into runtime.
• Added safeguards to prevent data overwrite when load fails by disabling save for affected components in that session.
• Added viewchain command support for compact blockchain overview (total blocks, total transactions, compact block list).
• Implemented CLI UI upgrades for jar users:
  • centralized visual rendering via CliVisuals
  • startup branding (logo + slogan)
  • authenticated shell prompt format (username@crypto1010 ~)
  • interactive tab auto-completion with pre-login and post-login suggestion scopes
• Added CLI robustness/security hardening:
  • sanitized terminal output to prevent control-sequence/ANSI injection from user-provided content
  • moved startup logo loading to bundled classpath resources (jar-safe, avoids CWD spoofing)
  • enforced wallet-name max length to reduce UI truncation/spoofing risk
  • upgraded account password storage to salted PBKDF2 hashing
  • implemented login brute-force throttling (temporary lockout after repeated failures)
  • added credential-file integrity signing and verification
  • added parser/storage size bounds to reduce oversized-input/file abuse risk
  • hardened save/rollback behavior to fail safe on persistence errors

Bug fixing and triaging (PE-D focus)

• Triaged and resolved multiple PE-D findings across functionality and docs, including parser correctness, command behavior consistency, persistence edge cases, and tutorial/session flow.
• Representative issues fixed include:
  • #183 (CreateCommand.resolveArguments dead no-op)
  • #182 (Wallet.setKeys validation sequencing)
  • #179 (create ... curr/generic handling)
  • #167 (user-facing warning noise for invalid commands)
  • #164 (DG startup instruction mismatch)
  • #152 (tutorial exit behavior)
  • #150 (extreme scientific notation freeze prevention)
  • #141 (UG quick start for end users)
  • #140 (blank blockchain file load behavior)
  • registration UX fix for immediate username validation on invalid input (related to #138)
• Triage approach used:
  • Reproduce from exact tester steps first
  • Classify as real bug vs accepted behavior
  • Apply minimal safe fix
  • Update tests/docs to prevent regressions and clarify expected behavior
  • Re-run unit, checkstyle, and text-ui regression after each fix batch

Contributions to the User Guide

• Documented startup authentication behavior (login/register) and account-scoped data model.
• Updated command documentation for crossSend and viewchain, including examples and command summary entries.
• Updated quick-start and behavior notes to better reflect real user and jar-run paths.
• Maintained data and persistence notes to reflect account-specific storage paths and current address/key persistence behavior.
• Added/updated CLI usability documentation:
  • startup branding and authenticated prompt format
  • tab auto-completion scope before and after login
  • terminal constraints for completion behavior
• Updated security/persistence documentation:
  • password hashing and temporary login lockout behavior
  • credential integrity signature and key file paths
  • save-failure fail-safe behavior and keygen regeneration restriction

Contributions to the Developer Guide

• Wrote/updated the Blockchain and Block implementation details:
  • architecture-level ownership of validation and append invariants
  • component-level design rationale and trade-offs
  • alternatives considered for validation and append APIs
• Added/updated UML diagrams for this area:
  • validation sequence diagram
  • send-to-append sequence diagram
  • blockchain/block class diagram
• Updated DG implementation and manual-testing details to stay aligned with current behavior after bug fixes.
• Added implementation notes for shell/completer architecture and mode switching between authentication and command phases.
• Added manual testing steps for tab completion scope transitions.
• Corrected wallet/crypto internals documentation to match actual KeyPair + secp256k1 implementation (removed stale RSA/Key references).
• Added DG coverage for authentication hardening (PBKDF2, lockout, credential-signature checks) and persistence/input hardening limits.

Contributions to team-based tasks

• Helped align blockchain behavior with command and storage layers so validation rules are enforced consistently in CLI and load-time paths.
• Performed integration fixes across parser, command registry, tests, and docs to keep releases stable.
• Coordinated bug triaging decisions with teammates (fix now / doc clarify / accept-as-designed) to reduce duplicate work during PE.

Review/mentoring contributions

• Reviewed teammate changes for command parsing, storage behavior, and test coverage consistency.
• Helped identify and prioritize correctness issues (load/save safety, parser edge cases, documentation mismatches) before merge.
• Supported teammate bug investigations by reproducing reports and narrowing root causes before patching.

Contributions beyond the project team

• Reported and analyzed project-level defects through GitHub issues and followed through with implementation and documentation updates.
• Contributed structured PE-D triage reasoning (severity, reproducibility, expected behavior) that improved issue turnaround and consistency.