Substitution Cipher

Substitution Cipher

Each letter in the plaintext is replaced by another letter according to a fixed system.

Key Format

The key must contain all 26 letters of the alphabet exactly once, representing the substitution mapping.

Frequency Analysis

Analyze character frequencies to help break substitution ciphers by comparing with expected English frequencies.

• • E is most common in English
• • Look for common patterns
• • Single letters are often A or I
• • THE is the most common word