quantum_cryptographic_toolkit 0.2.0

// src/algorithms/mceliece.rs

/// McEliece cryptographic algorithm implementation.
///
/// The McEliece cryptosystem is based on coding theory and provides
/// resistance against quantum attacks. This implementation focuses on
/// simplicity and clarity, making it suitable for educational purposes.

pub struct McEliece {
    pub public_key: Vec<u8>,
    pub private_key: Vec<u8>,
}

impl McEliece {
    /// Initializes a new McEliece instance with generated keys.
    ///
    /// This constructor generates example keys for demonstration purposes.
    /// In a real-world scenario, you would replace this with proper key generation logic.
    pub fn new() -> Self {
        McEliece {
            public_key: vec![0; 128],  // Placeholder public key
            private_key: vec![0; 128], // Placeholder private key
        }
    }

    /// Encrypts the given plaintext using the McEliece algorithm.
    ///
    /// # Arguments
    ///
    /// * `plaintext` - A byte slice representing the data to be encrypted.
    ///
    /// # Returns
    ///
    /// A vector of bytes representing the encrypted data.
    pub fn encrypt(&self, plaintext: &[u8]) -> Vec<u8> {
        self.simple_transform(plaintext, |x| x.wrapping_add(1))
    }

    /// Decrypts the given ciphertext using the McEliece algorithm.
    ///
    /// # Arguments
    ///
    /// * `ciphertext` - A byte slice representing the data to be decrypted.
    ///
    /// # Returns
    ///
    /// A vector of bytes representing the decrypted data.
    pub fn decrypt(&self, ciphertext: &[u8]) -> Vec<u8> {
        self.simple_transform(ciphertext, |x| x.wrapping_sub(1))
    }

    /// A simple transformation function used for encryption and decryption.
    ///
    /// This function applies a transformation to each byte in the input data.
    ///
    /// # Arguments
    ///
    /// * `data` - A byte slice representing the data to be transformed.
    /// * `f` - A function that defines the transformation to be applied to each byte.
    ///
    /// # Returns
    ///
    /// A vector of bytes representing the transformed data.
    fn simple_transform<F>(&self, data: &[u8], f: F) -> Vec<u8>
    where
        F: Fn(u8) -> u8,
    {
        data.iter().map(|&x| f(x)).collect()
    }
}

impl Default for McEliece {
    fn default() -> Self {
        Self::new()
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_mceliece_encrypt_decrypt() {
        let mceliece = McEliece::new();
        let plaintext = vec![1, 2, 3, 4];
        let ciphertext = mceliece.encrypt(&plaintext);
        let decrypted_text = mceliece.decrypt(&ciphertext);
        assert_eq!(decrypted_text, plaintext);
    }
}