Add Technical/picoCTF/t1/q2.md

Technical/picoCTF/t1/q2.md

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+Question: Easy1
+Key: picoCTF{CRYPTOISFUN}
+
+Core concept: Vignere Cypher - Decrypted character=(Encrypted character−Key character+26)mod26
+
+Can be solved by an easy Python script:
+
+```py
+def decrypt_vigenere(encrypted_text, key):
+    decrypted_text = ""
+    key_length = len(key)
+
+    for i in range(len(encrypted_text)):
+        encrypted_char_pos = ord(encrypted_text[i]) - ord('A')
+        key_char_pos = ord(key[i % key_length]) - ord('A')
+
+        decrypted_char_pos = (encrypted_char_pos - key_char_pos + 26) % 26
+
+        decrypted_char = chr(decrypted_char_pos + ord('A'))
+
+        decrypted_text += decrypted_char
+
+    return decrypted_text
+
+
+encrypted_flag = "UFJKXQZQUNB"
+key = "SOLVECRYPTO"
+
+decrypted_flag = decrypt_vigenere(encrypted_flag, key)
+print("Decrypted Flag:", decrypted_flag)
+```
+
+Output: CRYPTOISFUN