51 lines
1.7 KiB
Python
51 lines
1.7 KiB
Python
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#!/usr/bin/env python3
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import sys
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from pathlib import Path
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def load_pad(filename="cipher/data/daybook_master_example.txt"):
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"""Load the master pad file."""
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pad_text = Path(filename).read_text()
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# Extract only the 5-letter groups, ignore headers and spaces
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groups = [g for g in pad_text.split() if len(g) == 5 and g.isalpha()]
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return "".join(groups).upper()
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def encrypt_message(plaintext: str, pad: str, start_pos: int):
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"""Encrypt using the pad starting at a given position."""
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# Clean plaintext: uppercase letters only, remove everything else
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pt = "".join(c for c in plaintext.upper() if c.isalpha())
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if not pt:
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return "ERROR: No letters in message"
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ciphertext = []
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for i, char in enumerate(pt):
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if i + start_pos >= len(pad):
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return "ERROR: Pad exhausted! Generate new master."
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p = ord(pad[start_pos + i]) - 65
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c = ord(char) - 65
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d = (c + p) % 26
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ciphertext.append(chr(d + 65))
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# Format in 5-letter groups
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ct_str = "".join(ciphertext)
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return " ".join(ct_str[j:j + 5] for j in range(0, len(ct_str), 5))
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if __name__ == "__main__":
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if len(sys.argv) < 2:
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print("Usage: python3 encrypt.py 'Your secret message here' [start_page]")
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print("Example: python3 encrypt.py 'Meeting at the retro show on Saturday' 7")
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sys.exit(1)
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message = sys.argv[1]
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start_page = int(sys.argv[2]) if len(sys.argv) > 2 else 1
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pad_str = load_pad()
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# Each page = 50 letters (10 groups × 5)
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start_pos = (start_page - 1) * 50
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ct = encrypt_message(message, pad_str, start_pos)
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print(f"\n=== NERDLETTER SECRET MESSAGE (Use Day Book PAGE {start_page:03d}) ===")
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print(ct)
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print("\nCopy the line above to the website.")
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