dmsc 0.1.9

Ri - A high-performance Rust middleware framework with modular architecture
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//! Copyright © 2025-2026 Wenze Wei. All Rights Reserved.
//!
//! This file is part of Ri.
//! The Ri project belongs to the Dunimd Team.
//!
//! Licensed under the Apache License, Version 2.0 (the "License");
//! You may not use this file except in compliance with the License.
//! You may obtain a copy of the License at
//!
//!     http://www.apache.org/licenses/LICENSE-2.0
//!
//! Unless required by applicable law or agreed to in writing, software
//! distributed under the License is distributed on an "AS IS" BASIS,
//! WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//! See the License for the specific language governing permissions and
//! limitations under the License.

#![allow(non_snake_case)]

//! # Kyber KEM
//!
//! This module implements the Kyber Key Encapsulation Mechanism (KEM)
//! using liboqs. Kyber is IND-CCA2 secure and is based on the hardness
//! of the Module-LWE (Learning With Errors over Modules) problem.
//!
//! ## Security Level
//!
//! - **Kyber512**: NIST Level 1 ≈ AES-128
//! - **Kyber768**: NIST Level 3 ≈ AES-192
//! - **Kyber1024**: NIST Level 5 ≈ AES-256
//!
//! ## Usage
//!
//! ```rust,ignore
//! use ri::protocol::kyber::KyberKEM;
//!
//! let kem = KyberKEM::new();
//! let (public_key, secret_key) = kem.keygen()?;
//! let (ciphertext, shared_secret_1) = kem.encapsulate(&public_key)?;
//! let shared_secret_2 = kem.decapsulate(&ciphertext, &secret_key)?;
//! assert_eq!(shared_secret_1, shared_secret_2);
//! ```

use std::sync::Arc;
use crate::core::{RiResult, RiError};

#[derive(Debug, Clone)]
#[cfg_attr(feature = "pyo3", pyo3::prelude::pyclass)]
pub struct KyberPublicKey(pub Vec<u8>);

#[derive(Debug, Clone)]
#[cfg_attr(feature = "pyo3", pyo3::prelude::pyclass)]
pub struct KyberSecretKey(pub Vec<u8>);

#[derive(Debug, Clone)]
#[cfg_attr(feature = "pyo3", pyo3::prelude::pyclass)]
pub struct KyberCiphertext(pub Vec<u8>);

#[derive(Debug, Clone)]
#[cfg_attr(feature = "pyo3", pyo3::prelude::pyclass)]
pub struct KyberKEM {
    algorithm: Arc<std::sync::RwLock<KyberAlgorithm>>,
}

#[derive(Debug, Clone, Copy)]
enum KyberAlgorithm {
    Kyber512,
    Kyber768,
    Kyber1024,
}

impl KyberKEM {
    pub fn new() -> Self {
        Self {
            algorithm: Arc::new(std::sync::RwLock::new(KyberAlgorithm::Kyber512)),
        }
    }

    pub fn with_algorithm(algorithm: super::RiPostQuantumAlgorithm) -> Self {
        let algo = match algorithm {
            super::RiPostQuantumAlgorithm::Kyber512 => KyberAlgorithm::Kyber512,
            super::RiPostQuantumAlgorithm::Kyber768 => KyberAlgorithm::Kyber768,
            super::RiPostQuantumAlgorithm::Kyber1024 => KyberAlgorithm::Kyber1024,
            _ => KyberAlgorithm::Kyber512,
        };
        Self {
            algorithm: Arc::new(std::sync::RwLock::new(algo)),
        }
    }

    #[cfg(feature = "protocol")]
    pub fn keygen(&self) -> RiResult<(Vec<u8>, Vec<u8>)> {
        use oqs::kem::Kem;

        let algo = *self.algorithm.read().map_err(|e| 
            RiError::InvalidState(format!("Lock error: {}", e))
        )?;
        let kem = match algo {
            KyberAlgorithm::Kyber512 => Kem::new(oqs::kem::Algorithm::Kyber512),
            KyberAlgorithm::Kyber768 => Kem::new(oqs::kem::Algorithm::Kyber768),
            KyberAlgorithm::Kyber1024 => Kem::new(oqs::kem::Algorithm::Kyber1024),
        }.map_err(|e| RiError::Other(format!("Failed to initialize Kyber: {:?}", e)))?;

        let (pk, sk) = kem.keypair()
            .map_err(|e| RiError::Other(format!("Kyber keygen failed: {:?}", e)))?;
        Ok((pk.into_vec(), sk.into_vec()))
    }

    #[cfg(not(feature = "protocol"))]
    pub fn keygen(&self) -> RiResult<(Vec<u8>, Vec<u8>)> {
        Err(RiError::Other(
            "Post-quantum cryptography requires the 'protocol' feature. \
             Enable with: cargo build --features protocol".to_string()
        ))
    }

    #[cfg(feature = "protocol")]
    pub fn encapsulate(&self, public_key: &[u8]) -> RiResult<super::KEMResult> {
        use oqs::kem::Kem;

        let algo = *self.algorithm.read().map_err(|e| 
            RiError::InvalidState(format!("Lock error: {}", e))
        )?;
        let kem = match algo {
            KyberAlgorithm::Kyber512 => Kem::new(oqs::kem::Algorithm::Kyber512),
            KyberAlgorithm::Kyber768 => Kem::new(oqs::kem::Algorithm::Kyber768),
            KyberAlgorithm::Kyber1024 => Kem::new(oqs::kem::Algorithm::Kyber1024),
        }.map_err(|e| RiError::Other(format!("Failed to initialize Kyber: {:?}", e)))?;

        let pk = kem.public_key_from_bytes(public_key)
            .ok_or_else(|| RiError::Other("Invalid public key".to_string()))?;
        let (ct, ss) = kem.encapsulate(&pk)
            .map_err(|e| RiError::Other(format!("Kyber encapsulate failed: {:?}", e)))?;
        Ok(super::KEMResult {
            ciphertext: ct.into_vec(),
            shared_secret: ss.into_vec(),
        })
    }

    #[cfg(not(feature = "protocol"))]
    pub fn encapsulate(&self, _public_key: &[u8]) -> RiResult<super::KEMResult> {
        Err(RiError::Other(
            "Post-quantum cryptography requires the 'protocol' feature. \
             Enable with: cargo build --features protocol".to_string()
        ))
    }

    #[cfg(feature = "protocol")]
    pub fn decapsulate(&self, ciphertext: &[u8], secret_key: &[u8]) -> RiResult<Vec<u8>> {
        use oqs::kem::Kem;

        let algo = *self.algorithm.read().map_err(|e| 
            RiError::InvalidState(format!("Lock error: {}", e))
        )?;
        let kem = match algo {
            KyberAlgorithm::Kyber512 => Kem::new(oqs::kem::Algorithm::Kyber512),
            KyberAlgorithm::Kyber768 => Kem::new(oqs::kem::Algorithm::Kyber768),
            KyberAlgorithm::Kyber1024 => Kem::new(oqs::kem::Algorithm::Kyber1024),
        }.map_err(|e| RiError::Other(format!("Failed to initialize Kyber: {:?}", e)))?;

        let ct = kem.ciphertext_from_bytes(ciphertext)
            .ok_or_else(|| RiError::Other("Invalid ciphertext".to_string()))?;
        let sk = kem.secret_key_from_bytes(secret_key)
            .ok_or_else(|| RiError::Other("Invalid secret key".to_string()))?;
        let ss = kem.decapsulate(&sk, &ct)
            .map_err(|e| RiError::Other(format!("Kyber decapsulate failed: {:?}", e)))?;
        Ok(ss.into_vec())
    }

    #[cfg(not(feature = "protocol"))]
    pub fn decapsulate(&self, _ciphertext: &[u8], _secret_key: &[u8]) -> RiResult<Vec<u8>> {
        Err(RiError::Other(
            "Post-quantum cryptography requires the 'protocol' feature. \
             Enable with: cargo build --features protocol".to_string()
        ))
    }
}

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

#[cfg(feature = "pyo3")]
#[pyo3::prelude::pymethods]
impl KyberKEM {
    #[new]
    pub fn new_py() -> Self {
        Self::new()
    }

    pub fn keygen_py(&self) -> Option<(Vec<u8>, Vec<u8>)> {
        self.keygen().ok()
    }

    pub fn encapsulate_py(&self, public_key: &[u8]) -> Option<(Vec<u8>, Vec<u8>)> {
        self.encapsulate(public_key).ok().map(|r| (r.ciphertext, r.shared_secret))
    }

    pub fn decapsulate_py(&self, ciphertext: &[u8], secret_key: &[u8]) -> Option<Vec<u8>> {
        self.decapsulate(ciphertext, secret_key).ok()
    }
}