crypt_guard 3.0.1

//use super::*;

//use crypt_guard_proc::{*, log_activity, write_log};
use crate::{
    core::{
        // removed unused KyberKeyFunctions per clippy
        KeyControlVariant,
    },
    cryptography::{
        hmac_sign::{Operation, Sign, SignType},
        *,
    },
    error::*,
    *,
};
use aes::cipher::generic_array::GenericArray;
use aes_gcm_siv::{
    aead::{Aead, KeyInit},
    Aes256GcmSiv, Nonce,
};
use hex;
use hmac::{Hmac, Mac};
use rand::{rngs::OsRng, RngCore};
use sha2::Sha256;
use std::result::Result;

/// Generates a 12-byte iv using OS-level randomness.
///
/// # Returns
/// A 24-byte array filled with secure random bytes.
pub fn generate_iv() -> [u8; 12] {
    let mut iv = [0u8; 12];
    OsRng.fill_bytes(&mut iv);
    iv
}

fn derive_legacy_aes_gcm_siv_key(sharedsecret: &[u8], iv: &[u8]) -> Result<[u8; 32], CryptError> {
    type HmacSha256 = Hmac<Sha256>;
    let mut extract =
        <HmacSha256 as Mac>::new_from_slice(iv).expect("HMAC-SHA256 accepts any key length");
    extract.update(sharedsecret);
    let prk = extract.finalize().into_bytes();

    let mut expand =
        <HmacSha256 as Mac>::new_from_slice(&prk).expect("HMAC-SHA256 accepts any key length");
    expand.update(b"crypt_guard:legacy:aes-gcm-siv:key");
    expand.update(&[1]);
    let okm = expand.finalize().into_bytes();

    let mut key = [0u8; 32];
    key.copy_from_slice(&okm[..32]);
    Ok(key)
}

/// The main struct for handling cryptographic operations with ChaCha20 algorithm.
/// It encapsulates the cryptographic information, shared secret, and iv required for encryption and decryption.
impl CipherAesGcmSiv {
    /// Constructs a new CipherChaCha instance with specified cryptographic information and an optional iv.
    ///
    /// # Parameters
    /// - infos: Cryptographic information including content, passphrase, metadata, and location for encryption or decryption.
    /// - iv: Optional hexadecimal string representation of the iv. If not provided, a iv will be generated.
    ///
    /// # Returns
    /// A new CipherChaCha instance.
    pub fn new(infos: CryptographicInformation, iv: Option<String>) -> Self {
        let iv: Vec<u8> = match iv {
            Some(iv) => hex::decode(iv).expect("An error occoured while decoding hex!"),
            None => generate_iv().to_vec(),
        };
        // println!("infos: {:?}", infos);
        CipherAesGcmSiv {
            infos,
            sharedsecret: Vec::new(),
            iv,
        }
    }

    /// Retrieves the encrypted or decrypted data stored within the CryptographicInformation.
    ///
    /// # Returns
    /// A result containing the data as a vector of bytes (Vec<u8>) or a CryptError.
    pub fn get_data(&self) -> Result<Vec<u8>, CryptError> {
        let data = &self.infos.content()?;
        let data = data.to_vec();

        Ok(data)
    }
    /// Sets the shared secret for the cryptographic operation.
    ///
    /// # Parameters
    /// - sharedsecret: A vector of bytes (Vec<u8>) representing the shared secret.
    ///
    /// # Returns
    /// A reference to the CipherChaCha instance to allow method chaining.
    pub fn set_shared_secret(&mut self, sharedsecret: Vec<u8>) -> &Self {
        self.sharedsecret = sharedsecret;
        self
    }

    /// Retrieves the shared secret.
    ///
    /// # Returns
    /// A result containing a slice of the shared secret (&[u8]) or a CryptError.    
    pub fn sharedsecret(&self) -> Result<&[u8], CryptError> {
        Ok(&self.sharedsecret)
    }

    /// Sets the iv for cryptographic operations.
    ///
    /// # Parameters
    /// - iv: A vector of bytes representing the iv.
    ///
    /// # Returns
    /// A reference to the set iv (&Vec<u8>).
    pub fn set_iv(&mut self, iv: Vec<u8>) -> &Vec<u8> {
        self.iv = iv;
        &self.iv
    }

    /// Retrieves the iv.
    ///
    /// # Returns
    /// A reference to the current iv (&Vec<u8>).
    pub fn iv(&self) -> &Vec<u8> {
        &self.iv
    }

    fn encryption(&self) -> Result<(Vec<u8>, Vec<u8>), CryptError> {
        let plaintext = self.infos.content()?;
        let passphrase = self.infos.passphrase()?.to_vec();
        let derived_key = derive_legacy_aes_gcm_siv_key(&self.sharedsecret, &self.iv)?;
        let key = GenericArray::from_slice(&derived_key);
        let cipher = Aes256GcmSiv::new(key);
        let iv = Nonce::from_slice(&self.iv);
        let mut hmac = Sign::new(
            plaintext.to_vec(),
            passphrase,
            Operation::Sign,
            SignType::Sha512,
        );
        let data = hmac.hmac();
        let encrypted = cipher
            .encrypt(iv, &*data)
            .map_err(|e| CryptError::new(e.to_string().as_str()))?;
        let iv = self.iv();
        Ok((encrypted, iv.to_owned()))
    }

    fn decryption(&self) -> Result<(Vec<u8>, Vec<u8>), CryptError> {
        let ciphertext = self.infos.content()?;
        let passphrase = self.infos.passphrase()?.to_vec();
        let iv = Nonce::from_slice(&self.iv);
        let derived_key = derive_legacy_aes_gcm_siv_key(&self.sharedsecret, &self.iv)?;
        let cipher = Aes256GcmSiv::new(GenericArray::from_slice(&derived_key));
        let decrypted = match cipher.decrypt(iv, &*ciphertext.to_vec()) {
            Ok(decrypted) => decrypted,
            Err(_) => {
                let legacy_cipher = Aes256GcmSiv::new(GenericArray::from_slice(&self.sharedsecret));
                legacy_cipher
                    .decrypt(iv, &*ciphertext.to_vec())
                    .map_err(|e| CryptError::new(e.to_string().as_str()))?
            }
        };
        //println!("decrypted: {:?}", &decrypted);
        let mut hmac = Sign::new(
            decrypted.to_vec(),
            passphrase,
            Operation::Verify,
            SignType::Sha512,
        );
        let data = hmac.hmac();
        //println!("Verified: {:?}", &data);
        let iv = self.iv();
        Ok((data, iv.to_owned()))
    }
}

impl CryptographicFunctions for CipherAesGcmSiv {
    /// Encrypts the provided data using the public key.
    ///
    /// # Parameters
    /// - public_key: The public key used for encryption.
    ///
    /// # Returns
    /// A result containing a tuple of the encrypted data (Vec<u8>) and the key used, or a CryptError.
    /// Additionally, prints a message to stdout with the iv for user reference.
    fn encrypt(&mut self, public_key: Vec<u8>) -> Result<(Vec<u8>, Vec<u8>), CryptError> {
        let key = KeyControlVariant::new(self.infos.metadata.key_type()?);
        let (sharedsecret, ciphertext) = key.encap(&public_key)?;
        let _ = self.set_shared_secret(sharedsecret);
        let (encrypted_data, iv) = self.encryption()?;
        println!("Please write down this iv: {}", hex::encode(iv));
        Ok((encrypted_data, ciphertext))
    }

    /// Decrypts the provided data using the secret key and ciphertext.
    ///
    /// # Parameters
    /// - secret_key: The secret key used for decryption.
    /// - ciphertext: The ciphertext to decrypt.
    ///
    /// # Returns
    /// A result containing the decrypted data (Vec<u8>), or a CryptError.
    fn decrypt(&mut self, secret_key: Vec<u8>, ciphertext: Vec<u8>) -> Result<Vec<u8>, CryptError> {
        let key = KeyControlVariant::new(self.infos.metadata.key_type()?);
        let sharedsecret = key.decap(&secret_key, &ciphertext)?;
        let _ = self.set_shared_secret(sharedsecret);
        let (decrypted_data, _iv) = self.decryption()?;
        Ok(decrypted_data)
    }
}