Cipher Suite
Free online tools for encryption, decryption, and cryptanalysis. Learn how classical ciphers work and practice breaking them with our interactive tools.
Available Cipher Tools
Caesar Cipher
Classic shift cipher that moves each letter by a fixed amount. Includes auto-crack feature and frequency analysis.
Vigenère Cipher
Polyalphabetic cipher using a keyword. Features Kasiski examination and Index of Coincidence analysis.
Substitution Cipher
Monoalphabetic cipher with custom alphabet mapping. Interactive solving assistant with pattern matching.
XOR Cipher
Binary encryption using exclusive OR operation. Supports multiple input/output formats.
ROT13 Cipher
Self-inverse Caesar cipher with shift of 13. Commonly used for hiding spoilers online.
Affine Cipher
Mathematical cipher using E(x) = (ax + b) mod 26. Combines multiplication and addition.
Atbash Cipher
Ancient Hebrew cipher that reverses the alphabet (A↔Z, B↔Y). Self-inverse operation.
Rail Fence Cipher
Transposition cipher that writes text in zigzag pattern across multiple rails.
Playfair Cipher
Digraph cipher using 5×5 keyword matrix. First practical digraph substitution cipher.
One-Time Pad
Theoretically unbreakable cipher using random keys as long as the message.
Cipher Identifier
Auto-detect cipher types using frequency analysis, Index of Coincidence, and pattern matching.
Encoding Chain Analyzer
Detect and decode nested encodings like Base64→Hex→URL→ROT13 chains.
Cipher Comparison
| Cipher | Type | Key Space | Security | Best For |
|---|---|---|---|---|
| Caesar | Monoalphabetic | 26 | Very Weak | Learning basics |
| ROT13 | Fixed Caesar | 1 | None | Hiding spoilers |
| Substitution | Monoalphabetic | 26! (~4×10²⁶) | Weak | Puzzles, learning |
| Vigenère | Polyalphabetic | 26ⁿ (key length n) | Moderate | Intermediate learning |
| XOR | Stream cipher | 2ⁿ (key bits) | Variable | Binary operations |
| Affine | Mathematical | 312 | Weak | Learning modular math |
| Atbash | Fixed substitution | 1 | None | Historical study |
| Rail Fence | Transposition | n-1 (rails) | Very Weak | Transposition concepts |
| Playfair | Digraph | 25!/2 | Weak | Digraph analysis |
| One-Time Pad | XOR stream | ∞ (message length) | Perfect* | Perfect secrecy theory |
Understanding Classical Ciphers
What is a Cipher?
A cipher is a method of transforming a message (plaintext) into an unreadable format (ciphertext) to protect its contents. The original message can be recovered using the correct key or method.
Classical ciphers, like those in this suite, were used historically before the advent of computers. While no longer secure for modern use, they provide an excellent foundation for understanding cryptographic principles.
Types of Classical Ciphers
- Substitution:Each letter is replaced with another (Caesar, ROT13, general substitution)
- Polyalphabetic:Uses multiple substitution alphabets (Vigenère)
- Transposition:Letters are rearranged according to a pattern
- Stream:Combines plaintext with a key stream (XOR)
Cryptanalysis Techniques
- Frequency Analysis: Analyzing letter frequencies (E is most common in English)
- Pattern Recognition: Identifying common words like THE, AND, FOR
- Kasiski Examination: Finding repeated sequences in polyalphabetic ciphers
- Index of Coincidence: Statistical measure for detecting cipher type
- Known Plaintext Attack: Using known text to deduce the key
Security Warning
These ciphers are NOT secure for modern use. All classical ciphers can be broken by modern computers in seconds.
For real security, use modern encryption standards like AES-256, RSA, or TLS. These tools are intended for educational purposes, puzzles, and learning cryptography fundamentals.
Historical Ciphers
Enigma Machine
WWII (1920s-1940s)
Electromechanical rotor cipher machine
Ready to Learn Cryptography?
Start with the Caesar cipher to understand basic substitution, then progress to more complex ciphers. Each tool includes educational content and cryptanalysis features.
All cipher tools run entirely in your browser. No data is sent to our servers. For professional security needs, consult a cybersecurity expert or visit our cybersecurity services.