Merged PRs security audit

SECURITY_AUDIT_REPORT.md

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+# Security Audit Report — Last 10 Commits
+
+**Repository:** SuperChenSSS/Algorithm-Training  
+**Audit Date:** 2026-02-10  
+**Auditor:** Automated Cloud Agent  
+**Scope:** Last 10 commits on `master` branch (no merged PRs exist in this repository)
+
+---
+
+## Executive Summary
+
+This repository is a **personal ACM/ICPC competitive programming training repository** containing exclusively:
+- C/C++ algorithm solutions (Dijkstra, DP, graph theory, number theory, etc.)
+- Compiled binary executables
+- Test input/output `.txt` files
+- Saved HTML web pages (contest solutions from BestCoder Blog, CSDN, ICPCCamp, Coursera)
+- PDF reference materials (textbooks, contest problem sets)
+- JetBrains `.idea/` IDE configuration files
+
+**No security vulnerabilities or data leaks were found.**
+
+---
+
+## Commits Reviewed
+
+| # | Commit | Date | Message | Files Changed |
+|---|--------|------|---------|---------------|
+| 1 | `7257df0` | 2018-05-26 | New commit | 46 |
+| 2 | `8dcafa5` | 2017-10-08 | Update | 5 |
+| 3 | `8c0f3f0` | 2017-10-01 | Training | 57 |
+| 4 | `3974b30` | 2017-09-25 | Nannjing Commit | 17 |
+| 5 | `13c822a` | 2017-09-21 | Fundamental finished | 14 |
+| 6 | `ded0cf1` | 2017-09-19 | Update | 2 |
+| 7 | `bf310ab` | 2017-09-19 | Hard Training | 31 |
+| 8 | `b49cb92` | 2017-09-16 | Xian Onsite | 30 |
+| 9 | `aef1167` | 2017-09-14 | Modified 9.14 | 14 |
+| 10 | `8284e5b` | 2017-09-09 | Modified in 9.9 | 27 |
+
+---
+
+## Detailed Findings
+
+### 1. Hardcoded Credentials / API Keys / Secrets
+**Status: NONE FOUND**
+
+Searched all source code, configuration files, and text files for:
+- Passwords, API keys, secret tokens, bearer tokens
+- AWS access keys (`AKIA...`), GitHub tokens (`ghp_...`), OpenAI keys (`sk-...`)
+- SSH private keys, PEM certificates, private key files
+- Database connection strings, JDBC URLs
+- `.env` files, `.pem` files, `.key` files
+
+No matches. All `@Author` annotations in `.cpp` files contain only initials ("CMY"), not email addresses or credentials.
+
+### 2. Sensitive Data Exposure
+**Status: NONE FOUND**
+
+- No personal data (emails, phone numbers, addresses) in source code
+- No database dumps, SQL files, or backup files
+- No configuration files with production settings
+- The `.idea/workspace.xml` file is a standard JetBrains IDE workspace config — contains no secrets, just UI layout preferences and a project-level UUID
+
+### 3. Compiled Binaries in Repository
+**Status: INFORMATIONAL (Low Risk)**
+
+**~285 compiled ELF executables** are committed to the repository (files without extensions). These are compiled outputs of the C++ algorithm solutions. Examples: `51NOD刷题/RMQ`, `C++&STL/map`, `Challenge/图论/Dij`, etc.
+
+- **Risk:** Compiled binaries can theoretically contain embedded malware. However, these are clearly the compiled counterparts of adjacent `.cpp` source files and are typical of a student learning environment.
+- **Recommendation:** Add a `.gitignore` to exclude compiled binaries. They bloat the repository and serve no version-control purpose.
+
+### 4. Saved Web Pages
+**Status: INFORMATIONAL (No Security Risk)**
+
+Multiple complete web pages were saved (via browser "Save As" or SingleFile extension) from:
+- BestCoder Blog (contest solution editorials)
+- CSDN Blog
+- ICPCCamp forum posts
+- Coursera (a CNN quiz page in `ACM模板/图论/1.html`)
+
+These contain standard third-party JavaScript libraries (jQuery, MathJax, KaTeX) and embedded base64 font/image data. The JavaScript files reference generic patterns like `password` and `token` in the context of DOM manipulation and form handling, which triggered pattern matches but represent **zero actual risk** — they are standard library code from public CDNs.
+
+### 5. Large Files in Repository
+**Status: INFORMATIONAL (No Security Risk)**
+
+Several large files are committed:
+- `The_Art_of_Computer_Programming - Vol 1.pdf` (~36 MB)
+- Contest problem set PDFs (~11-18 MB each)
+- `GG.txt` (10,000,000 lines — a test data generator output)
+
+These cause repository bloat but pose no security risk.
+
+### 6. Buffer Overflow / Unsafe Code Patterns
+**Status: INFORMATIONAL (No Practical Risk)**
+
+The C++ code uses `scanf`, `strcpy`, fixed-size arrays (`char buf[1000010]`), and other patterns that would be buffer overflow risks in production software. However, this is competitive programming code intended exclusively for online judges — it processes trusted input and is never deployed in any security-sensitive context.
+
+---
+
+## Vulnerability Scan Summary
+
+| Category | Severity | Count |
+|----------|----------|-------|
+| Hardcoded Credentials | — | 0 |
+| API Keys / Tokens | — | 0 |
+| Private Keys / Certificates | — | 0 |
+| Sensitive Data Files (.env, .key, .pem) | — | 0 |
+| Database Credentials | — | 0 |
+| SQL Injection Vectors | — | 0 |
+| Dependency Vulnerabilities | — | N/A (no dependency management files) |
+| Compiled Binaries | Informational | ~285 |
+| Large Committed Files | Informational | ~5 |
+| Unsafe C Code Patterns | Informational | ~100+ files |
+
+---
+
+## Conclusion
+
+**This repository contains zero security vulnerabilities and zero data leaks.**
+
+It is a straightforward student algorithm training repository with no web services, no network code, no authentication systems, no configuration files with secrets, and no deployed applications. The only actionable recommendation is to add a `.gitignore` file to exclude compiled binaries and large test data files from version control.
+
+---
+
+## Note on Methodology
+
+This repository has **zero pull requests** (open, closed, or merged). All 10 reviewed changes were direct commits to `master`. The audit was conducted by:
+1. Reviewing the full diff of each commit (text files only; binary changes noted by stat)
+2. Searching the entire repository for sensitive patterns (credentials, keys, tokens, certificates)
+3. Checking for sensitive file types (.env, .pem, .key, .p12, .pfx, .sql, .db)
+4. Checking deleted file history for any previously-committed secrets
+5. Inspecting IDE configuration files for embedded credentials