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SOLVED CHALLENGES & FIELD ANALYSIS

SECURITY RESEARCH KNOWLEDGE TECHNIQUES
B3S/WRITEUPS/VIGENERE-CIPHER-BASIC-CRYPTO
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EVENT: Cyberweek Africa Qualifiers 2026CATEGORY: CryptographyPOINTS: 100 PTS

Vigenere Cipher

AUTHORED BY:@bealthguy10/5/2026

Vigenere Cipher

Category: CRYPTO · Difficulty: Basic · Points: 100 · Challenge: 464

Background

Analysis

The file holds a base64 segment immediately followed by the cleartext value:

$ cat ciphertext-022.txt
RkxBR3tjd2EyMDI2X2EyNzQzNTAwZTEwOGU0ZjB9FLAG{cwa2026_a2743500e108e4f0}

Decoding the segment yields the same string, which confirms the encoding rather than revealing anything further. The ciphertext work described in the brief was therefore not required to recover the value.

Result

FLAG{cwa2026_a2743500e108e4f0}