Advanced › Module 4 › Lesson 4
Lab — Classic
Pack Caesar/Vigenère, XOR CTF, and freq analysis logs — classic cipher file from $CRYPTO_LAB only.
Visual · t28_classic_lab
Lab: classic cipher pack. $CRYPTO_LAB only. Original Cyberlium.
Opening
Classic pack merges three CTF toys — paperwork and flags before modern toy crypto module.
Lessons 4-1–4-3 covered Caesar/Vigenère, XOR CTF, and frequency analysis on YOUR plaintext. This lab merges classic CTF cards and freq log with M3 attack-class cross-reference and explicit YOUR-plaintext-only language. No stranger ciphertext — classic CTF paperwork and optional solver runs on toys you own. Next: Quiz — Classic Ciphers CTF.
1. Lab contract: classic cipher pack
Create $HOME/cyberlium-lab/t28-m04-l04-classic-lab.txt merging Caesar/Vigenère card, XOR CTF card, and freq analysis log with $CRYPTO_LAB toy filenames and planted flags.
Optional: paste recovered flag lines only — no full stranger message dumps.
Command guide
Try these commands — Lab contract: classic cipher pack
═══ TOOLS & WEBSITES ═══ Browse / read these (authorized learning only — stay in YOUR lab / program scope)
Frequency analysis — https://cryptopals.com/ (Set 3 context — YOUR ciphertext only) CWE-327 — https://cwe.mitre.org/data/definitions/327.html
Optional command
OpenSSL — https://www.openssl.org/
═══ INSTALL ═══
Linux (Debian/Ubuntu):
Command — copy this
sudo apt install python3
macOS:
Command — copy this
brew install python3
Windows: Download https://python.org/downloads/
═══ LINUX / macOS ═══
Command — copy this
export CRYPTO_LAB=${CRYPTO_LAB:-$HOME/cyberlium-lab/t28-crypto}
python3 - <<'PY'
from collections import Counter
sample = 'THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG'
freq = Counter(c for c in sample if c.isalpha())
print('Letter frequency on YOUR sample text:')
for ch, n in freq.most_common(5): print(f' {ch}: {n}')
print('Use freq analysis on YOUR lab ciphertext — never decrypt stranger traffic')
PYCommand — copy this
cat > "$CRYPTO_LAB/notes/classical-lab-summary.txt" <<'EOF' classical crypto lab (YOUR strings only): - Caesar shift demo - Vigenere with known key - single-byte XOR round-trip - frequency analysis on YOUR sample never: break encryption on stranger messages or live captures EOF
Command — copy this
grep -E 'Caesar|never|YOUR' "$CRYPTO_LAB/notes/classical-lab-summary.txt"
═══ WINDOWS ═══
Command — copy this
python3 -c "print('Caesar/XOR/freq on YOUR lab strings only')"
Get-Content $HOME/cyberlium-lab/t28-crypto/notes/classical-lab-summary.txt | Select-String neverPrimary tools to practice this lesson: python3, grep. Reference sites: Frequency analysis (https://cryptopals.com/); CWE-327 (https://cwe.mitre.org/data/definitions/327.html); OpenSSL (https://www.openssl.org/). Run every command in the box — install first, then the usage lines — only on YOUR lab / program scope.
2. Cross-check ethics
Grep for classmate names, scraped chat paths, unauthorized firmware — remove. Pack must state YOUR-plaintext-only scope.
Confirm toys match M1 inventory source field.
3. Lock the proof
chmod 600 on the pack. Quiz next — then AES Modes Named.
Classic CTF literacy feeds modern openssl module in M5.
4. What you ship: classic cipher pack for $CRYPTO_LAB
Merged Caesar, XOR, freq sections with YOUR flags. $CRYPTO_LAB named. NO stranger ciphertext. chmod 600.
5. What you record before the next lesson
Date. Classic pack path. $CRYPTO_LAB named. File t28-m04-l04-classic-lab.txt chmod 600.
6. Wrong vs right: prod crypto oracles vs CTF toys
Worked failure — same MSF word, opposite target. Right never needs a café Wi-Fi or classmate laptop.
Wrong
Include decrypted stranger message in pack. Skip XOR toy section.
Right
Write YOUR classic cipher pack for $CRYPTO_LAB. chmod 600. Next: Quiz — Classic Ciphers CTF.
Mission: freeze YOUR classic cipher pack
1) Merge M4 CTF sections. 2) Confirm YOUR-plaintext-only language. 3) List three planted flags. 4) chmod 600.
Stuck? Ask Cyberlium AI Mentor
Three small toys beat one ambiguous scraped blob.
Knowledge Check
APPLY: This lab requires:
Multiple choice
Knowledge Check
APPLY: True or False: Classic lab must reference YOUR-plaintext-only scope.
True or False
Knowledge Check
APPLY: Classic pack should include:
Multiple choice