Griffinere Cipher 🔐

The Griffinere cipher is a custom encryption algorithm in C# designed for reversible, base64-normalized encryption using a repeating key. Inspired by the Vigenère cipher, it adds configurable alphabet support, input validation, and padding-based encryption length enforcement.

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📦 Installation

Install from the Nuget Library:

dotnet add package SubstitutionCiphers

In your code:

using Ciphers;

✨ Features

🔐 Encrypts and decrypts alphanumeric or custom alphabet-based strings

🔐 Double pass-through encryption, which allows for a second passthrough of the encryption method for additional obfuscation

🧩 Allows defining your own alphabet

📏 Supports minimum-length encrypted responses via padding

✅ Includes strong validation for alphabet and key integrity

🧪 Unit tested with xUnit

🧰 Usage

1.1: Creating the Cipher Using the default alphabet:

const string key = "YourSecureKey";
Griffinere cipher = new(key);

Default alphabet includes:

A-Z
a-z
0-9

1.2: Creating the Cipher Using a custom alphabet:

const string customAlphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ12345";
const string key = "YOURKEY";
Griffinere cipher = new(customAlphabet, key);

Alphabet Rules

1. Must not contain . (dot character)
2. All characters must be unique
3. All characters in the key must exist in the alphabet

2.1: Encrypt a String

Griffinere cipher = new("nGOvtaRXyMEtCOO9");
string plainText = "Hello World 123";
string encrypted = cipher.EncryptString(plainText);
//outputs: sjnyIdM trIKZ3v 0m7m

2.2: Encrypt a String with Minimum Length

Griffinere cipher = new("nGOvtaRXyMEtCOO9");
const string plainText = "Hello World 123";
string encrypted = cipher.EncryptString(plainText, minimumResponseLength: 24);
//outputs: w5WFeRLvJ1q.sjnyIdM trIKZ3v 0m7m.c

2.3: Encrypt with Double Pass Through

Griffinere cipher = new("dShHPpUQTihcn7ju1wjYTAD1dvbrPKdT", isEnableDoublePassThrough: true);
const string plainText = "ThisIsAnExampleOfDoublePassThrough";
string encrypted = cipher.EncryptString(plainText, minimumResponseLength: 48);
//outputs: 90d9Hm1jNk31aDLO8ksiQagRDTlRkEenY0FqyReoJ9Vic3wbx15BHowoq2zifhyW5cspbWAx3jQYAxAIc0QkrS5cxm

3.1: Decrypt a String

string decrypted = cipher.DecryptString(encrypted);
// Returns the original plain text