Implement at-rest encryption: AES-256-GCM VFS layer
- Added encrypted_fs.rs module for transparent file encryption - EncryptedVfs wraps any VfsBackend with AES-256-GCM encryption - Per-file key derivation from master key + file path (SHA-256) - File format: MBE1 magic + version + nonce + original_size + ciphertext + tag - EncryptedFile transparently decrypts on read, encrypts on flush - 5 unit tests: roundtrip, different keys, key derivation, header format, password config Tests: 457 markbase-core (+5 new), 201 smb-server (658 total)
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Warren
344
markbase-core/src/vfs/encrypted_fs.rs
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344
markbase-core/src/vfs/encrypted_fs.rs
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//! Encrypted VFS Backend - Transparent at-rest encryption using AES-256-GCM
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//!
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//! This module provides transparent file encryption at the VFS layer.
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//! Files are encrypted before being written to disk and decrypted on read.
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//!
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//! Format:
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//! - Header (32 bytes): magic(4) + version(4) + nonce(12) + original_size(8) + reserved(4)
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//! - Body: AES-256-GCM encrypted data
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//! - Tag (16 bytes): GCM authentication tag
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use std::path::PathBuf;
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use std::io::{Seek, SeekFrom};
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use aes_gcm::{
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Aes256Gcm, Nonce, aead::{Aead, KeyInit},
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};
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use sha2::{Sha256, Digest};
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use super::{VfsBackend, VfsFile, VfsStat, VfsError, VfsDirEntry};
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use super::open_flags::OpenFlags;
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use super::local_fs::LocalFs;
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const ENCRYPTED_MAGIC: &[u8] = b"MBE1"; // MarkBase Encrypted v1
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const ENCRYPTED_VERSION: u32 = 1;
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const HEADER_SIZE: usize = 32;
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const TAG_SIZE: usize = 16;
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const NONCE_SIZE: usize = 12;
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const KEY_SIZE: usize = 32;
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#[derive(Debug, Clone)]
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pub struct EncryptedVfsConfig {
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pub master_key: Vec<u8>, // 32 bytes for AES-256
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pub encrypt_filenames: bool, // Future feature
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}
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impl EncryptedVfsConfig {
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pub fn new(master_key: [u8; 32]) -> Self {
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Self {
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master_key: master_key.to_vec(),
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encrypt_filenames: false,
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}
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}
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pub fn from_password(password: &str) -> Self {
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let mut hasher = Sha256::new();
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hasher.update(password.as_bytes());
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let key = hasher.finalize();
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Self {
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master_key: key.to_vec(),
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encrypt_filenames: false,
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}
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}
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}
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pub struct EncryptedVfs {
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inner: Box<dyn VfsBackend>,
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config: EncryptedVfsConfig,
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}
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impl EncryptedVfs {
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pub fn new(inner: Box<dyn VfsBackend>, config: EncryptedVfsConfig) -> Self {
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Self { inner, config }
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}
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pub fn wrap_local_fs(root: PathBuf, config: EncryptedVfsConfig) -> Self {
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Self::new(Box::new(LocalFs::new()), config)
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}
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fn derive_key(&self, path: &PathBuf) -> Vec<u8> {
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let mut hasher = Sha256::new();
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hasher.update(&self.config.master_key);
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hasher.update(path.to_string_lossy().as_bytes());
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let derived = hasher.finalize();
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derived[..KEY_SIZE].to_vec()
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}
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pub fn is_encrypted_file(data: &[u8]) -> bool {
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data.len() >= HEADER_SIZE + TAG_SIZE && &data[..4] == ENCRYPTED_MAGIC
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}
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fn encrypt_data(&self, path: &PathBuf, data: &[u8]) -> Result<Vec<u8>, VfsError> {
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let key_bytes = self.derive_key(path);
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let cipher = Aes256Gcm::new_from_slice(&key_bytes)
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.map_err(|e| VfsError::Io(format!("cipher init failed: {}", e)))?;
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let nonce_bytes: [u8; NONCE_SIZE] = rand_key(12).try_into().map_err(|_| VfsError::Io("nonce generation failed".to_string()))?;
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let nonce = Nonce::from_slice(&nonce_bytes);
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let ciphertext = cipher.encrypt(nonce, data)
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.map_err(|e| VfsError::Io(format!("encryption failed: {}", e)))?;
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let mut result = Vec::with_capacity(HEADER_SIZE + ciphertext.len() + TAG_SIZE);
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result.extend_from_slice(ENCRYPTED_MAGIC);
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result.extend_from_slice(&ENCRYPTED_VERSION.to_le_bytes());
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result.extend_from_slice(&nonce_bytes);
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result.extend_from_slice(&(data.len() as u64).to_le_bytes());
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result.extend_from_slice(&[0u8; 4]);
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result.extend_from_slice(&ciphertext);
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Ok(result)
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}
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fn decrypt_data(&self, path: &PathBuf, data: &[u8]) -> Result<Vec<u8>, VfsError> {
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if !Self::is_encrypted_file(data) {
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return Err(VfsError::Io("not an encrypted file".to_string()));
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}
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let key_bytes = self.derive_key(path);
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let cipher = Aes256Gcm::new_from_slice(&key_bytes)
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.map_err(|e| VfsError::Io(format!("cipher init failed: {}", e)))?;
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let nonce_bytes: [u8; NONCE_SIZE] = data[8..20].try_into().map_err(|_| VfsError::Io("invalid nonce".to_string()))?;
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let nonce = Nonce::from_slice(&nonce_bytes);
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let original_size = u64::from_le_bytes(data[20..28].try_into().map_err(|_| VfsError::Io("invalid size".to_string()))?) as usize;
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let ciphertext = &data[HEADER_SIZE..];
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let plaintext = cipher.decrypt(nonce, ciphertext)
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.map_err(|e| VfsError::Io(format!("decryption failed: {}", e)))?;
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if plaintext.len() != original_size {
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return Err(VfsError::Io(format!("size mismatch: expected {}, got {}", original_size, plaintext.len())));
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}
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Ok(plaintext)
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}
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}
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fn rand_key(len: usize) -> Vec<u8> {
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use std::time::{SystemTime, UNIX_EPOCH};
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let now = SystemTime::now().duration_since(UNIX_EPOCH).unwrap().as_nanos();
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let mut hasher = Sha256::new();
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hasher.update(&now.to_le_bytes());
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hasher.update(&[0u8; 32]);
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let hash = hasher.finalize();
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hash[..len].to_vec()
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}
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pub struct EncryptedFile {
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inner: Box<dyn VfsFile>,
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path: PathBuf,
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config: EncryptedVfsConfig,
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decrypted_data: Option<Vec<u8>>,
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modified: bool,
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position: u64,
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}
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impl EncryptedFile {
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fn decrypt_on_open(&mut self) -> Result<(), VfsError> {
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let encrypted = self.inner.read_all()?;
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if EncryptedVfs::is_encrypted_file(&encrypted) {
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let vfs = EncryptedVfs::new(Box::new(LocalFs::new()), self.config.clone());
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self.decrypted_data = Some(vfs.decrypt_data(&self.path, &encrypted)?);
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} else {
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self.decrypted_data = Some(encrypted);
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}
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Ok(())
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}
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fn encrypt_on_close(&mut self) -> Result<(), VfsError> {
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if !self.modified {
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return Ok(());
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}
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let data = self.decrypted_data.as_ref().ok_or_else(|| VfsError::Io("no data to encrypt".to_string()))?;
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let vfs = EncryptedVfs::new(Box::new(LocalFs::new()), self.config.clone());
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let encrypted = vfs.encrypt_data(&self.path, data)?;
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self.inner.seek(SeekFrom::Start(0))?;
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self.inner.write_all(&encrypted)?;
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Ok(())
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}
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}
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impl VfsFile for EncryptedFile {
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fn read(&mut self, buf: &mut [u8]) -> Result<usize, VfsError> {
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if self.decrypted_data.is_none() {
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self.decrypt_on_open()?;
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}
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let data = self.decrypted_data.as_ref().ok_or_else(|| VfsError::Io("no decrypted data".to_string()))?;
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let start = self.position as usize;
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let end = std::cmp::min(start + buf.len(), data.len());
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if start >= data.len() {
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return Ok(0);
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}
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buf[..(end - start)].copy_from_slice(&data[start..end]);
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self.position += (end - start) as u64;
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Ok(end - start)
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}
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fn write(&mut self, buf: &[u8]) -> Result<usize, VfsError> {
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if self.decrypted_data.is_none() {
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self.decrypted_data = Some(Vec::new());
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}
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let data = self.decrypted_data.as_mut().ok_or_else(|| VfsError::Io("no decrypted data".to_string()))?;
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let start = self.position as usize;
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if start + buf.len() > data.len() {
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data.resize(start + buf.len(), 0);
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}
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data[start..start + buf.len()].copy_from_slice(buf);
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self.position += buf.len() as u64;
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self.modified = true;
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Ok(buf.len())
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}
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fn seek(&mut self, pos: SeekFrom) -> Result<u64, VfsError> {
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match pos {
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SeekFrom::Start(offset) => {
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self.position = offset;
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}
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SeekFrom::Current(offset) => {
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self.position = (self.position as i64 + offset) as u64;
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}
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SeekFrom::End(offset) => {
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let len = self.decrypted_data.as_ref().map(|d| d.len() as i64).unwrap_or(0);
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self.position = (len + offset) as u64;
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}
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}
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Ok(self.position)
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}
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fn flush(&mut self) -> Result<(), VfsError> {
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self.encrypt_on_close()?;
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self.inner.flush()?;
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Ok(())
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}
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fn stat(&mut self) -> Result<VfsStat, VfsError> {
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let stat = self.inner.stat()?;
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Ok(VfsStat {
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size: self.decrypted_data.as_ref().map(|d| d.len() as u64).unwrap_or(stat.size),
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mode: stat.mode,
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uid: stat.uid,
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gid: stat.gid,
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atime: stat.atime,
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mtime: stat.mtime,
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is_dir: false,
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is_symlink: false,
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})
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}
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fn set_len(&mut self, size: u64) -> Result<(), VfsError> {
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if self.decrypted_data.is_none() {
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self.decrypted_data = Some(Vec::new());
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}
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let data = self.decrypted_data.as_mut().ok_or_else(|| VfsError::Io("no decrypted data".to_string()))?;
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data.resize(size as usize, 0);
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self.modified = true;
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Ok(())
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_encrypt_decrypt_roundtrip() {
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let config = EncryptedVfsConfig::from_password("test_password");
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let path = PathBuf::from("/test/file.txt");
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let vfs = EncryptedVfs::new(Box::new(LocalFs::new()), config.clone());
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let original = b"Hello, World! This is a test message.";
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let encrypted = vfs.encrypt_data(&path, original).unwrap();
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assert!(encrypted.len() > original.len());
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assert!(EncryptedVfs::is_encrypted_file(&encrypted));
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let decrypted = vfs.decrypt_data(&path, &encrypted).unwrap();
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assert_eq!(decrypted, original);
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}
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#[test]
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fn test_different_keys_produce_different_ciphertext() {
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let config1 = EncryptedVfsConfig::from_password("password1");
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let config2 = EncryptedVfsConfig::from_password("password2");
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let path = PathBuf::from("/test/file.txt");
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let vfs1 = EncryptedVfs::new(Box::new(LocalFs::new()), config1);
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let vfs2 = EncryptedVfs::new(Box::new(LocalFs::new()), config2);
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let original = b"Same content";
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let enc1 = vfs1.encrypt_data(&path, original).unwrap();
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let enc2 = vfs2.encrypt_data(&path, original).unwrap();
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assert_ne!(enc1, enc2);
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}
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#[test]
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fn test_key_derivation() {
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let config = EncryptedVfsConfig::from_password("test_password");
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let vfs = EncryptedVfs::new(Box::new(LocalFs::new()), config);
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let key1 = vfs.derive_key(&PathBuf::from("/file1.txt"));
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let key2 = vfs.derive_key(&PathBuf::from("/file2.txt"));
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assert_ne!(key1, key2);
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}
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#[test]
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fn test_header_format() {
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let config = EncryptedVfsConfig::from_password("test");
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let path = PathBuf::from("/test.txt");
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let vfs = EncryptedVfs::new(Box::new(LocalFs::new()), config);
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let data = b"test";
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let encrypted = vfs.encrypt_data(&path, data).unwrap();
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assert_eq!(&encrypted[..4], ENCRYPTED_MAGIC);
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assert_eq!(u32::from_le_bytes(encrypted[4..8].try_into().unwrap()), ENCRYPTED_VERSION);
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assert_eq!(encrypted.len(), HEADER_SIZE + data.len() + TAG_SIZE);
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}
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#[test]
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fn test_config_from_password() {
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let config = EncryptedVfsConfig::from_password("my_secret_password");
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assert_eq!(config.master_key.len(), KEY_SIZE);
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let config2 = EncryptedVfsConfig::from_password("my_secret_password");
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assert_eq!(config.master_key, config2.master_key);
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let config3 = EncryptedVfsConfig::from_password("different");
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assert_ne!(config.master_key, config3.master_key);
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}
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}
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@@ -1,6 +1,7 @@
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pub mod cache;
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pub mod compression;
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pub mod dedup;
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pub mod encrypted_fs;
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pub mod local_fs;
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pub mod open_flags;
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pub mod raid;
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