รหัสลับ
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How to solve
Decoding Flow (Reverse Order):
Encoded → Layer 10: Base64 Decode → Layer 9: Remove Markers → Layer 8: Triple Base64 Decode → Layer 7: Undo Group Transform → Layer 6: Remove Pattern → Layer 5: Undo Position Shifts → Layer 4: Reverse → Layer 3: Undo ROT13 → Layer 2: Undo Substitution → Layer 1: Base64 Decode → Original
DECODING PROCESS (In reverse order)
Layer 10: Base64 Decoding
1. Decode the string using standard Base64 decoding rules
2. This will reveal text with embedded marker characters
Layer 9: Remove Marker Characters
1. Every 11th character is a marker character (starting after the 10th character)
2. The markers follow the pattern "MARKER" repeated as needed
3. Remove all these markers to get the Layer 8 encoded text
Layer 8: Triple Base64 Decoding
1. Apply Base64 decoding three times in succession
2. Each decode operation converts the string to a new, shorter encoded string
3. After three decodes, you'll get the interleaved pattern text
Layer 7: Group Transformation
1. Split the text into chunks of 3 characters each
2. For even-positioned chunks (0-indexed), reverse the characters
3. Leave odd-positioned chunks as they are
4. Concatenate all chunks back together
5. This reconstructs the original Layer 6 text
Layer 6: Pattern Interleaving
1. Every other character is part of a fixed pattern "X1Y2Z3" repeated throughout
2. Keep only the characters at even positions (0, 2, 4, etc.)
3. Discard all the odd-positioned pattern characters
Layer 5: Position-based Shift
1. For each alphabetic character at position i:
- Determine if it's uppercase or lowercase
- Shift it back by (i % 7) positions in its alphabet
- Formula for each letter: ((ascii_value - base - shift + 26) % 26) + base
- Where base is 'a' (97) for lowercase or 'A' (65) for uppercase
Layer 4: String Reversal
1. Simply reverse the entire string (last character becomes first, etc.)
Layer 3: ROT13 Decoding
1. For each alphabetic character, shift it 13 positions backward in the alphabet
2. For lowercase: ((char_value - 'a' - 13) % 26) + 'a'
3. For uppercase: ((char_value - 'A' - 13) % 26) + 'A'
4. Non-alphabetic characters remain unchanged
Layer 2: Simple Substitution
1. For alphabetic characters: shift backward by 5 places in the alphabet
- For lowercase: ((char_value - 'a' - 5) % 26) + 'a'
- For uppercase: ((char_value - 'A' - 5) % 26) + 'A'
2. For numeric digits: shift backward by 3
- ((digit_value - '0' - 3) % 10) + '0'
3. Non-alphanumeric characters remain unchanged
Layer 1: Base64 Decoding
1. Apply one final standard Base64 decode operation
2. Convert the resulting bytes to text to get the original message