Ciphertext Input
Decrypted Text
0 charactersDECRYPTION MODE
OPTIONS
How It Works:
- • Vigenere Mode: Uses the key as a repeating pattern for alphabetic shift decryption
- • XOR Mode: Applies bitwise XOR operation between ciphertext and key (mathematically unbreakable when key length equals message length)
- • The same key used for encryption must be used for decryption
- • All processing happens locally in your browser - no data is transmitted
Letters to Numbers
Trusted Conversion Tools
Vernam Cipher Decoder
Vernam Cipher Decoder - Decrypt Vernam (one-time pad) ciphertext with the original key. This tool supports both Vigenere mode for alphabetic shift decryption and XOR mode for bitwise operations, providing mathematically unbreakable cipher decryption when used properly. All processing happens locally in your browser for maximum security.
Who Is It For?
Cryptography Enthusiasts
Understanding and implementing one-time pad ciphers and Vernam encryption
Security Researchers
Analyzing theoretically unbreakable cipher systems and encryption methods
Military & Intelligence Personnel
Decrypting historical and modern one-time pad communications
Computer Science Students
Learning advanced cryptography concepts and mathematical encryption principles
How It Works
Enter the ciphertext into the left panel and provide the original encryption key in the key field. Select your decryption mode (Vigenere for alphabetic cipher or XOR for bitwise operations). The tool decrypts the message in real-time using the selected algorithm. Toggle "Preserve case" to maintain original letter capitalization. All decryption happens locally in your browser with no data transmission.
Features
- Vigenere mode decryption for alphabetic ciphers
- XOR mode for bitwise one-time pad decryption
- Real-time decryption with instant results
- Preserve case option for maintaining formatting
- Copy decrypted text to clipboard
- Download decrypted messages as text files
- Character counting for both input and output
- Complete offline processing for security
Other Tools
Explore more tools by clicking the + button above
Your Privacy Matters
All processing happens in your browser. We never store, send, or log your data. Completely private and secure.