Buggy cipher decryption - need help fixing decode issues
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CipherDebugger
Posted on January 18, 2025 • Advanced
🔐 Buggy cipher - decryption not working properly!
I’m working on a cipher project and I’m having major issues with the decryption process. The encryption seems to work fine, but when I try to decrypt the message, I get garbled text or completely wrong characters.
UPDATE: I’ve been debugging this for hours and I think the issue might be with how I’m handling the character mapping or the shift values. The encrypted text looks correct, but decryption is completely broken.
Here are the specific problems I’m encountering:
- 🔤 Decrypted text shows random characters instead of original message
- 🔢 Some characters decrypt correctly, others don’t
- ⚠️ Special characters and spaces cause the whole system to break
- 🔄 The shift values seem inconsistent during decryption
- 📝 Longer messages have more errors than shorter ones
I’ve tried different approaches but nothing seems to work. Can someone please help me identify what’s going wrong with my cipher algorithm? This is really frustrating! 😤
CryptoExpert_Master
Replied 1 hour later • ⭐ Best Answer
I can help you fix this @CipherDebugger! Cipher bugs are usually caused by inconsistent encoding/decoding logic or improper character handling. Let me show you how to build a robust cipher system that works reliably:
🔍 Cipher Debugging Flow
Here’s the systematic approach to debug and fix cipher issues:
🔧 Step 1: Create Robust Character Set
First, define a consistent character mapping system:
when flag clicked // Define character set (A-Z, a-z, 0-9, space, punctuation) set [alphabet v] to [ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789 .,!?] set [alphabet size v] to (length of (alphabet)) // Test character mapping set [test char v] to [A] set [char position v] to (position of (test char) in (alphabet)) say (join [Character ] (join (test char) (join [ is at position ] (char position)))) for [2] seconds
🔐 Step 2: Build Encryption Function
Create a proper encryption function with error checking:
// Encryption function define encrypt character (char) with shift (shift) set [char pos v] to (position of (char) in (alphabet)) if <(char pos) = [0]> then // Character not in alphabet, return as-is set [encrypted char v] to (char) else // Apply Caesar cipher with wrapping set [new pos v] to (((char pos) + (shift)) mod (alphabet size)) if <(new pos) = [0]> then set [new pos v] to (alphabet size) end set [encrypted char v] to (letter (new pos) of (alphabet)) end
🔓 Step 3: Build Decryption Function
The key is making decryption the exact reverse of encryption:
// Decryption function (reverse of encryption) define decrypt character (char) with shift (shift) set [char pos v] to (position of (char) in (alphabet)) if <(char pos) = [0]> then // Character not in alphabet, return as-is set [decrypted char v] to (char) else // Reverse the shift with proper wrapping set [new pos v] to (((char pos) - (shift)) mod (alphabet size)) if <(new pos) < [1]> then set [new pos v] to ((new pos) + (alphabet size)) end set [decrypted char v] to (letter (new pos) of (alphabet)) end
🔄 Step 4: Handle Full Message Processing
Process messages character by character with proper error handling:
// Full message encryption define encrypt message (message) with shift (shift) set [encrypted message v] to [] set [char index v] to [1] repeat (length of (message)) set [current char v] to (letter (char index) of (message)) encrypt character (current char) with shift (shift) ::custom set [encrypted message v] to (join (encrypted message) (encrypted char)) change [char index v] by [1] end // Full message decryption define decrypt message (message) with shift (shift) set [decrypted message v] to [] set [char index v] to [1] repeat (length of (message)) set [current char v] to (letter (char index) of (message)) decrypt character (current char) with shift (shift) ::custom set [decrypted message v] to (join (decrypted message) (decrypted char)) change [char index v] by [1] end
🧪 Step 5: Testing and Validation
Always test your cipher with various inputs:
// Comprehensive cipher testing when flag clicked // Test 1: Single character set [test char v] to [A] set [shift v] to [3] encrypt character (test char) with shift (shift) ::custom decrypt character (encrypted char) with shift (shift) ::custom if <(decrypted char) = (test char)> then say [✅ Single character test passed] for [1] seconds else say [❌ Single character test failed] for [1] seconds end wait [1] seconds // Test 2: Full message set [original v] to [Hello World!] encrypt message (original) with shift (shift) ::custom decrypt message (encrypted message) with shift (shift) ::custom if <(decrypted message) = (original)> then say [✅ Full message test passed] for [1] seconds else say [❌ Full message test failed] for [1] seconds end
🛠️ Step 6: Debug Common Issues
Here are solutions for the most common cipher problems:
🔍 Issue: Modulo Calculation Errors
// Safe modulo function for negative numbers define safe mod (number) by (divisor) set [result v] to ((number) mod (divisor)) if <(result) < [0]> then set [result v] to ((result) + (divisor)) end // Use this instead of direct mod operation
⚡ Issue: Character Not Found
// Robust character position finding define find char position (char) set [pos v] to [1] set [found v] to [false] repeat (alphabet size) if <(letter (pos) of (alphabet)) = (char)> then set [char position v] to (pos) set [found v] to [true] stop [this script v] end change [pos v] by [1] end if <not (found)> then set [char position v] to [0] // Not found end
🎯 Issue: Boundary Conditions
// Handle edge cases properly define safe encrypt (char) shift (shift) // Normalize shift to alphabet size set [normalized shift v] to ((shift) mod (alphabet size)) // Handle empty or invalid input if <(char) = []> then set [result v] to [] else if <(length of (char)) > [1]> then set [result v] to (char) // Don't encrypt multi-char strings else // Normal encryption encrypt character (char) with shift (normalized shift) ::custom set [result v] to (encrypted char) end end
🔧 Step 7: Complete Working Cipher
Here’s a complete, debugged cipher implementation:
when flag clicked // Initialize cipher system set [alphabet v] to [ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789 .,!?-] set [alphabet size v] to (length of (alphabet)) // Demo: Encrypt and decrypt a message set [original message v] to [Hello, World! This is a test message 123.] set [cipher shift v] to [7] say (join [Original: ] (original message)) for [2] seconds wait [2] seconds encrypt message (original message) with shift (cipher shift) ::custom say (join [Encrypted: ] (encrypted message)) for [3] seconds wait [3] seconds decrypt message (encrypted message) with shift (cipher shift) ::custom say (join [Decrypted: ] (decrypted message)) for [3] seconds // Verify it worked if <(decrypted message) = (original message)> then say [🎉 Cipher working perfectly!] for [2] seconds else say [❌ Cipher has bugs - check your logic] for [2] seconds end
🔍 Debugging Checklist
- ✅ Character set includes all needed characters
- ✅ Modulo operations handle negative numbers correctly
- ✅ Decryption is exact reverse of encryption
- ✅ Boundary conditions (first/last characters) work
- ✅ Special characters are handled consistently
- ✅ Test with various shift values and message lengths
This should completely fix your cipher bugs! The key is systematic testing and proper modulo arithmetic.
Vibelf_Community
Pinned Message • Moderator
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