A type of substitution cipher.
It shifts a letter in a [[Plaintext]] by a fixed number of position in the alphabet to produce the [[Ciphertext]]
```mermaid
flowchart LR
subgraph "Key Concept"
key[Shift Key: 3]
end
subgraph "Cipher Process"
A[Original Plaintext: HELLO] -->|Step 1: Apply Shift Key| B{Substitution Process}
key -->|Define Rotation| B
B -->|Step 2: Shift Each Letter| C[Resulting Ciphertext: KHOOR]
end
subgraph "Letter-by-Letter Mapping"
original["Original: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z"]
shifted["Shifted: D E F G H I J K L M N O P Q R S T U V W X Y Z A B C"]
H["H → K"]
E["E → H"]
L1["L → O"]
L2["L → O"]
O["O → R"]
end
subgraph "Security Analysis"
insecure["Weaknesses:"]-->freq["Vulnerable to Frequency Analysis"]
insecure-->brute["Only 25 Possible Keys (Brute Force)"]
insecure-->pattern["Pattern Preservation"]
end
class A plaintext
class C ciphertext
class B process
class key key
class original plaintext
class shifted ciphertext
```
#Cybersecurity #ProgrammingFundamentals #TerminologyDefinitions #ConceptExplanation #Beginner