2026-08-21 13:51:31 +07:00
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---
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title: "Julius — ROT13 Caesar Cipher"
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2026-08-21 14:28:04 +07:00
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type: "writeup"
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section: "writeups"
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status: "published"
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author: "asep"
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tags: ["gemastik", "ctf", "warmup", "crypto"]
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path: "writeups/gemastik-2026-warmup/ch2-julius.md"
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created_at: "2026-08-21T07:25:20.120Z"
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updated_at: "2026-08-21T07:25:20.120Z"
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2026-08-21 13:51:31 +07:00
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event: "GEMASTIK 2026 Warmup"
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2026-08-21 14:28:04 +07:00
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challenge: "Julius — ROT13 Caesar Cipher"
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2026-08-21 13:51:31 +07:00
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category: "crypto"
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points: 500
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difficulty: "easy"
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flag: "GEMASTIK19{caesar_r0t_th1rt33n_klasik}"
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---
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# Julius (500 pts) — Caesar / ROT13
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**File:** `chall.txt` → `TRZNFGVX19{pnrfne_e0g_gu1eg33a_xynfvx}`
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Caesar cipher dengan pergeseran paling populer di internet = **ROT13** (geser 13).
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`TRZNFGVX19` → `GEMASTIK19`, dst.
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```python
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import codecs
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s = "TRZNFGVX19{pnrfne_e0g_gu1eg33a_xynfvx}"
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flag = codecs.encode(s, "rot_13")
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print(f"Flag: {flag}")
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# Output: GEMASTIK19{caesar_r0t_th1rt33n_klasik}
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```
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## Flag
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2026-08-21 14:28:04 +07:00
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`GEMASTIK19{caesar_r0t_th1rt33n_klasik}`
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