quantum_cryptographic_toolkit 0.2.0

// src/algorithms/sike.rs

/// SIKE (Supersingular Isogeny Key Encapsulation) cryptographic algorithm implementation.
///
/// SIKE is an isogeny-based encryption algorithm that provides post-quantum security.
/// This implementation focuses on clarity and demonstrates the core concepts of the SIKE algorithm.

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

impl Sike {
    /// Initializes a new SIKE instance with generated keys.
    ///
    /// This constructor generates example keys for demonstration purposes.
    /// In a real-world scenario, proper key generation logic should be implemented.
    pub fn new() -> Self {
        Sike {
            public_key: vec![0; 64],  // Placeholder public key
            private_key: vec![0; 64], // Placeholder private key
        }
    }

    /// Simulates key encapsulation using the SIKE algorithm.
    ///
    /// # Returns
    ///
    /// A vector of bytes representing the encapsulated key.
    pub fn encapsulate(&self) -> Vec<u8> {
        self.simple_transform(&self.public_key, |x| x.wrapping_add(1))
    }

    /// Simulates key decapsulation using the SIKE algorithm.
    ///
    /// # Arguments
    ///
    /// * `encapsulated_key` - A byte slice representing the encapsulated key.
    ///
    /// # Returns
    ///
    /// A vector of bytes representing the decapsulated key.
    pub fn decapsulate(&self, encapsulated_key: &[u8]) -> Vec<u8> {
        self.simple_transform(encapsulated_key, |x| x.wrapping_sub(1))
    }

    /// A simple transformation function used for encapsulation and decapsulation.
    ///
    /// 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 Sike {
    fn default() -> Self {
        Self::new()
    }
}

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

    #[test]
    fn test_sike_encapsulate_decapsulate() {
        let sike = Sike::new();
        let encapsulated_key = sike.encapsulate();
        let decapsulated_key = sike.decapsulate(&encapsulated_key);
        assert_eq!(decapsulated_key, sike.public_key);
    }

    #[test]
    fn test_sike_encapsulation_consistency() {
        let sike = Sike::new();
        let first_encapsulated_key = sike.encapsulate();
        let second_encapsulated_key = sike.encapsulate();
        assert_eq!(first_encapsulated_key, second_encapsulated_key);
    }

    #[test]
    fn test_sike_decapsulation_consistency() {
        let sike = Sike::new();
        let encapsulated_key = sike.encapsulate();
        let first_decapsulated_key = sike.decapsulate(&encapsulated_key);
        let second_decapsulated_key = sike.decapsulate(&encapsulated_key);
        assert_eq!(first_decapsulated_key, second_decapsulated_key);
    }
}