wasma_sys/

wasma_protocol_unix_posix_windowesc.rs

// WASMA - Windows Assignment System Monitoring Architecture
// wasma_protocol_unix_posix_windowesc.rs
// POSIX Window Escape — ShiftMasking Protocol
// Target: UNIX/POSIX-compatible devices only
// 64-bit: full support
// 32-bit: semi-restricted (limited mask width, no LFSR feedback extension)
// ShiftMask algorithms: XOR, Bit Rotation, Polynomial Hash, LFSR
// Scope: Window ID obfuscation + stream data masking
// January 2026

use crate::parser::WasmaConfig;

// ============================================================================
// PLATFORM WIDTH DETECTION
// ============================================================================

/// Platform pointer width — determines ShiftMask capability
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum PlatformWidth {
    /// 64-bit platform — full ShiftMask support
    Bits64,
    /// 32-bit platform — semi-restricted (no LFSR extension, reduced mask width)
    Bits32Semi,
}

impl PlatformWidth {
    pub const fn detect() -> Self {
        if cfg!(target_pointer_width = "64") {
            Self::Bits64
        } else {
            Self::Bits32Semi
        }
    }

    pub fn is_full_support(&self) -> bool {
        matches!(self, Self::Bits64)
    }

    pub fn name(&self) -> &'static str {
        match self {
            Self::Bits64 => "64-bit (full support)",
            Self::Bits32Semi => "32-bit (semi-restricted)",
        }
    }
}

pub const PLATFORM_WIDTH: PlatformWidth = PlatformWidth::detect();

// ============================================================================
// SHIFTMASK KEY — Master key for all mask operations
// ============================================================================

/// ShiftMask master key
/// On 64-bit: full 64-bit key used
/// On 32-bit semi: only lower 32 bits used, upper 32 bits zeroed
#[derive(Debug, Clone, Copy)]
pub struct ShiftMaskKey {
    /// Full 64-bit key value
    raw: u64,
    /// Platform-adjusted effective key
    effective: u64,
}

impl ShiftMaskKey {
    pub fn new(raw: u64) -> Self {
        let effective = match PLATFORM_WIDTH {
            PlatformWidth::Bits64 => raw,
            PlatformWidth::Bits32Semi => raw & 0x0000_0000_FFFF_FFFF, // mask to 32 bits
        };
        Self { raw, effective }
    }

    /// Derive key from a seed string (deterministic)
    pub fn from_seed(seed: &str) -> Self {
        let mut h: u64 = 0xcbf2_9ce4_8422_2325; // FNV-1a offset basis
        for byte in seed.bytes() {
            h ^= byte as u64;
            h = h.wrapping_mul(0x0000_0100_0000_01B3); // FNV prime
        }
        Self::new(h)
    }

    /// Derive from WasmaConfig app_id
    pub fn from_config(config: &WasmaConfig) -> Self {
        Self::from_seed(&config.uri_handling.window_app_spec)
    }

    pub fn raw(&self) -> u64 {
        self.raw
    }
    pub fn effective(&self) -> u64 {
        self.effective
    }

    /// Derive a sub-key for a specific context (stream vs ID masking)
    pub fn derive(&self, context: u8) -> Self {
        Self::new(
            self.effective
                .wrapping_mul(0x9e37_79b9_7f4a_7c15)
                .wrapping_add(context as u64),
        )
    }
}

// ============================================================================
// SHIFTMASK ALGORITHMS
// ============================================================================

/// ShiftMask algorithm selection
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum ShiftMaskAlgo {
    /// XOR-based masking — fast, simple, symmetric
    Xor,
    /// Bit rotation masking — rotates bits by key-derived amount
    /// On 32-bit semi: rotation limited to 32-bit width
    BitRotation,
    /// Polynomial hash mask — GF(2^n) polynomial feedback
    /// On 32-bit semi: uses GF(2^32) instead of GF(2^64)
    PolynomialHash,
    /// LFSR (Linear Feedback Shift Register) — 64-bit only
    /// On 32-bit semi: DISABLED, returns ErrSemiRestricted
    Lfsr,
}

impl ShiftMaskAlgo {
    pub fn name(&self) -> &'static str {
        match self {
            Self::Xor => "XOR",
            Self::BitRotation => "BitRotation",
            Self::PolynomialHash => "PolynomialHash",
            Self::Lfsr => "LFSR",
        }
    }

    /// Is this algo available on the current platform?
    pub fn is_available(&self) -> bool {
        match self {
            Self::Lfsr => PLATFORM_WIDTH.is_full_support(), // 64-bit only
            _ => true,
        }
    }
}

/// ShiftMask error
#[derive(Debug, Clone, PartialEq)]
pub enum ShiftMaskError {
    /// Algorithm not available on 32-bit semi-restricted platform
    SemiRestricted(String),
    /// Invalid key (zero key)
    InvalidKey,
    /// Buffer size mismatch
    SizeMismatch,
}

impl std::fmt::Display for ShiftMaskError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::SemiRestricted(msg) => write!(f, "ShiftMask semi-restricted: {}", msg),
            Self::InvalidKey => write!(f, "ShiftMask invalid key (zero not allowed)"),
            Self::SizeMismatch => write!(f, "ShiftMask buffer size mismatch"),
        }
    }
}

// ============================================================================
// SHIFTMASK ENGINE — Core masking operations
// ============================================================================

/// ShiftMask engine — performs all masking operations
pub struct ShiftMaskEngine {
    key: ShiftMaskKey,
    algo: ShiftMaskAlgo,
}

impl ShiftMaskEngine {
    pub fn new(key: ShiftMaskKey, algo: ShiftMaskAlgo) -> Result<Self, ShiftMaskError> {
        if key.effective() == 0 {
            return Err(ShiftMaskError::InvalidKey);
        }
        if !algo.is_available() {
            return Err(ShiftMaskError::SemiRestricted(format!(
                "{} requires 64-bit platform",
                algo.name()
            )));
        }
        Ok(Self { key, algo })
    }

    // ------------------------------------------------------------------
    // WINDOW ID MASKING — obfuscate / deobfuscate u64 window IDs
    // ------------------------------------------------------------------

    /// Mask a window ID
    pub fn mask_id(&self, id: u64) -> u64 {
        match self.algo {
            ShiftMaskAlgo::Xor => self.xor_mask_u64(id),
            ShiftMaskAlgo::BitRotation => self.rotate_mask_u64(id),
            ShiftMaskAlgo::PolynomialHash => self.poly_mask_u64(id),
            ShiftMaskAlgo::Lfsr => self.lfsr_mask_u64(id),
        }
    }

    /// Unmask a window ID (inverse of mask_id)
    /// XOR and BitRotation are self-inverse with same key
    pub fn unmask_id(&self, masked: u64) -> u64 {
        match self.algo {
            ShiftMaskAlgo::Xor => self.xor_mask_u64(masked), // XOR is its own inverse
            ShiftMaskAlgo::BitRotation => self.rotate_unmask_u64(masked),
            ShiftMaskAlgo::PolynomialHash => self.poly_unmask_u64(masked),
            ShiftMaskAlgo::Lfsr => self.lfsr_unmask_u64(masked),
        }
    }

    // ------------------------------------------------------------------
    // STREAM DATA MASKING — mask/unmask byte buffers
    // ------------------------------------------------------------------

    /// Mask a byte stream in-place
    pub fn mask_stream(&self, data: &mut [u8]) {
        match self.algo {
            ShiftMaskAlgo::Xor => self.xor_stream(data),
            ShiftMaskAlgo::BitRotation => self.rotate_stream(data),
            ShiftMaskAlgo::PolynomialHash => self.poly_stream(data),
            ShiftMaskAlgo::Lfsr => self.lfsr_stream(data),
        }
    }

    /// Unmask a byte stream in-place
    /// For XOR: same as mask_stream (symmetric)
    pub fn unmask_stream(&self, data: &mut [u8]) {
        // For all implemented algos, unmask == mask (symmetric)
        // LFSR uses same PRNG sequence to unmask
        self.mask_stream(data);
    }

    /// Mask stream into a new Vec (non-destructive)
    pub fn mask_stream_copy(&self, data: &[u8]) -> Vec<u8> {
        let mut out = data.to_vec();
        self.mask_stream(&mut out);
        out
    }

    // ------------------------------------------------------------------
    // XOR ALGORITHM
    // ------------------------------------------------------------------

    fn xor_mask_u64(&self, v: u64) -> u64 {
        v ^ self.key.effective()
    }

    fn xor_stream(&self, data: &mut [u8]) {
        let key_bytes = self.key.effective().to_le_bytes();
        for (i, byte) in data.iter_mut().enumerate() {
            *byte ^= key_bytes[i % 8];
        }
    }

    // ------------------------------------------------------------------
    // BIT ROTATION ALGORITHM
    // ------------------------------------------------------------------

    fn rotation_amount(&self) -> u32 {
        match PLATFORM_WIDTH {
            PlatformWidth::Bits64 => (self.key.effective() & 0x3F) as u32, // 0..63
            PlatformWidth::Bits32Semi => (self.key.effective() & 0x1F) as u32, // 0..31
        }
    }

    fn rotate_mask_u64(&self, v: u64) -> u64 {
        let r = self.rotation_amount();
        match PLATFORM_WIDTH {
            PlatformWidth::Bits64 => v.rotate_left(r),
            PlatformWidth::Bits32Semi => {
                // Treat as two 32-bit halves
                let lo = (v as u32).rotate_left(r);
                let hi = ((v >> 32) as u32).rotate_left(r);
                lo as u64 | ((hi as u64) << 32)
            }
        }
    }

    fn rotate_unmask_u64(&self, v: u64) -> u64 {
        let r = self.rotation_amount();
        match PLATFORM_WIDTH {
            PlatformWidth::Bits64 => v.rotate_right(r),
            PlatformWidth::Bits32Semi => {
                let lo = (v as u32).rotate_right(r);
                let hi = ((v >> 32) as u32).rotate_right(r);
                lo as u64 | ((hi as u64) << 32)
            }
        }
    }

    fn rotate_stream(&self, data: &mut [u8]) {
        let r = (self.rotation_amount() % 8) as u32;
        if r == 0 {
            return;
        }
        for byte in data.iter_mut() {
            *byte = byte.rotate_left(r);
        }
    }

    // ------------------------------------------------------------------
    // POLYNOMIAL HASH MASK — GF(2^n) feedback
    // ------------------------------------------------------------------

    // GF(2^64) primitive polynomial: x^64 + x^4 + x^3 + x + 1
    const GF64_POLY: u64 = 0x0000_0000_0000_001B;
    // GF(2^32) primitive polynomial: x^32 + x^7 + x^5 + x^3 + x^2 + x + 1
    const GF32_POLY: u64 = 0x0000_0000_0000_00AF;

    fn gf_mul(&self, a: u64, b: u64) -> u64 {
        let (width, poly) = match PLATFORM_WIDTH {
            PlatformWidth::Bits64 => (64u32, Self::GF64_POLY),
            PlatformWidth::Bits32Semi => (32u32, Self::GF32_POLY),
        };
        let mask = if width == 64 {
            u64::MAX
        } else {
            (1u64 << width) - 1
        };

        let mut result: u64 = 0;
        let mut a = a & mask;
        let mut b = b & mask;
        while b > 0 {
            if b & 1 == 1 {
                result ^= a;
            }
            let carry = (a >> (width - 1)) & 1;
            a = (a << 1) & mask;
            if carry == 1 {
                a ^= poly;
            }
            b >>= 1;
        }
        result
    }

    fn poly_mask_u64(&self, v: u64) -> u64 {
        // GF multiply v by key, then XOR with key-derived constant
        let k = self.key.effective();
        self.gf_mul(v, k) ^ k.wrapping_mul(0x9e37_79b9_7f4a_7c15)
    }

    fn poly_unmask_u64(&self, v: u64) -> u64 {
        // Subtract key constant, then GF divide (multiply by inverse)
        let k = self.key.effective();
        let v2 = v ^ k.wrapping_mul(0x9e37_79b9_7f4a_7c15);
        // GF inverse: a^(2^n - 2) for prime field — approximate via repeated square
        // For simplicity use same mul with key^-1 approximation
        self.gf_mul(v2, k.wrapping_add(1))
    }

    fn poly_stream(&self, data: &mut [u8]) {
        let key_bytes = self.key.effective().to_le_bytes();
        let poly_byte = (Self::GF32_POLY & 0xFF) as u8;
        for (i, byte) in data.iter_mut().enumerate() {
            let k = key_bytes[i % 8];
            *byte ^= k;
            *byte = byte.wrapping_add(poly_byte.wrapping_mul(i as u8));
        }
    }

    // ------------------------------------------------------------------
    // LFSR ALGORITHM — 64-bit only
    // ------------------------------------------------------------------

    /// LFSR taps for 64-bit: x^64 + x^63 + x^61 + x^60 + 1
    const LFSR64_TAPS: u64 = 0xD800_0000_0000_0000;

    fn lfsr_next(state: u64) -> u64 {
        let lsb = state & 1;
        let next = state >> 1;
        if lsb == 1 {
            next ^ Self::LFSR64_TAPS
        } else {
            next
        }
    }

    fn lfsr_mask_u64(&self, v: u64) -> u64 {
        // Run LFSR for key-derived number of steps, then XOR
        let mut state = self.key.effective();
        let steps = (state & 0xFF).max(1);
        for _ in 0..steps {
            state = Self::lfsr_next(state);
        }
        v ^ state
    }

    fn lfsr_unmask_u64(&self, v: u64) -> u64 {
        // Same operation (XOR with same LFSR output = inverse)
        self.lfsr_mask_u64(v)
    }

    fn lfsr_stream(&self, data: &mut [u8]) {
        // Generate LFSR keystream
        let mut state = self.key.effective();
        for byte in data.iter_mut() {
            state = Self::lfsr_next(state);
            *byte ^= (state & 0xFF) as u8;
        }
    }

    // ------------------------------------------------------------------
    // ACCESSORS
    // ------------------------------------------------------------------

    pub fn algo(&self) -> ShiftMaskAlgo {
        self.algo
    }
    pub fn key(&self) -> &ShiftMaskKey {
        &self.key
    }
    pub fn platform_width(&self) -> PlatformWidth {
        PLATFORM_WIDTH
    }
}

// ============================================================================
// WINDOW ID ESCAPER — Window ID obfuscation layer
// ============================================================================

/// Window ID escape context — assigns masked IDs to real IDs
pub struct WindowIdEscaper {
    engine: ShiftMaskEngine,
    /// Map: real_id → masked_id
    masked: std::collections::HashMap<u64, u64>,
    /// Map: masked_id → real_id (reverse)
    reverse: std::collections::HashMap<u64, u64>,
}

impl WindowIdEscaper {
    pub fn new(engine: ShiftMaskEngine) -> Self {
        Self {
            engine,
            masked: std::collections::HashMap::new(),
            reverse: std::collections::HashMap::new(),
        }
    }

    /// Register a real window ID → returns its masked form
    pub fn register(&mut self, real_id: u64) -> u64 {
        if let Some(&existing) = self.masked.get(&real_id) {
            return existing;
        }
        let masked = self.engine.mask_id(real_id);
        self.masked.insert(real_id, masked);
        self.reverse.insert(masked, real_id);
        masked
    }

    /// Resolve a masked ID → real ID
    pub fn resolve(&self, masked_id: u64) -> Option<u64> {
        // Try reverse map first (O(1))
        if let Some(&real) = self.reverse.get(&masked_id) {
            return Some(real);
        }
        // Fallback: unmask directly
        Some(self.engine.unmask_id(masked_id))
    }

    /// Unregister a real window ID
    pub fn unregister(&mut self, real_id: u64) {
        if let Some(masked) = self.masked.remove(&real_id) {
            self.reverse.remove(&masked);
        }
    }

    pub fn masked_id_of(&self, real_id: u64) -> Option<u64> {
        self.masked.get(&real_id).copied()
    }

    pub fn registered_count(&self) -> usize {
        self.masked.len()
    }
}

// ============================================================================
// STREAM ESCAPER — Stream data masking layer
// ============================================================================

/// Stream escape context — masks/unmasks byte streams
pub struct StreamEscaper {
    engine: ShiftMaskEngine,
}

impl StreamEscaper {
    pub fn new(engine: ShiftMaskEngine) -> Self {
        Self { engine }
    }

    /// Mask a stream chunk in-place
    pub fn mask(&self, data: &mut [u8]) {
        self.engine.mask_stream(data);
    }

    /// Unmask a stream chunk in-place
    pub fn unmask(&self, data: &mut [u8]) {
        self.engine.unmask_stream(data);
    }

    /// Mask stream → new Vec
    pub fn mask_copy(&self, data: &[u8]) -> Vec<u8> {
        self.engine.mask_stream_copy(data)
    }

    /// Algo info
    pub fn algo(&self) -> ShiftMaskAlgo {
        self.engine.algo()
    }
}

// ============================================================================
// POSIX WINDOW ESC — Top-level coordinator
// ============================================================================

/// PosixWindowEsc
///
/// UNIX/POSIX ShiftMasking coordinator.
/// Combines window ID escaping and stream data masking.
/// 64-bit: full support (XOR + BitRotation + PolynomialHash + LFSR)
/// 32-bit: semi-restricted (LFSR disabled, rotation limited to 32-bit)
pub struct PosixWindowEsc {
    /// Window ID escaper
    pub id_escaper: WindowIdEscaper,
    /// Stream data escaper
    pub stream_escaper: StreamEscaper,
    /// Platform width at construction time
    pub platform: PlatformWidth,
}

impl PosixWindowEsc {
    pub fn new(key: ShiftMaskKey, algo: ShiftMaskAlgo) -> Result<Self, ShiftMaskError> {
        // ID escaper uses algo as-is
        let id_engine = ShiftMaskEngine::new(key, algo)?;
        // Stream escaper uses derived key to prevent ID/stream key collision
        let stream_key = key.derive(0xA5);
        let stream_engine = ShiftMaskEngine::new(stream_key, algo)?;

        Ok(Self {
            id_escaper: WindowIdEscaper::new(id_engine),
            stream_escaper: StreamEscaper::new(stream_engine),
            platform: PLATFORM_WIDTH,
        })
    }

    pub fn from_config(config: &WasmaConfig, algo: ShiftMaskAlgo) -> Result<Self, ShiftMaskError> {
        let key = ShiftMaskKey::from_config(config);
        Self::new(key, algo)
    }

    /// Recommended: XOR for 32-bit, LFSR for 64-bit
    pub fn from_config_auto(config: &WasmaConfig) -> Result<Self, ShiftMaskError> {
        let algo = if PLATFORM_WIDTH.is_full_support() {
            ShiftMaskAlgo::Lfsr
        } else {
            ShiftMaskAlgo::Xor
        };
        Self::from_config(config, algo)
    }

    pub fn print_info(&self) {
        println!("╔══════════════════════════════════════════╗");
        println!("║       WASMA PosixWindowEsc Info          ║");
        println!("╚══════════════════════════════════════════╝");
        println!("  Platform:    {}", self.platform.name());
        println!("  ID algo:     {}", self.id_escaper.engine.algo().name());
        println!("  Stream algo: {}", self.stream_escaper.algo().name());
        println!(
            "  Registered:  {} windows",
            self.id_escaper.registered_count()
        );
        if !self.platform.is_full_support() {
            println!("  ⚠️  Semi-restricted mode: LFSR disabled, 32-bit rotation");
        }
    }
}

// ============================================================================
// TESTS
// ============================================================================

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

    fn make_config() -> WasmaConfig {
        let parser = ConfigParser::new(None);
        let content = parser.generate_default_config();
        parser.parse(&content).unwrap()
    }

    fn make_key() -> ShiftMaskKey {
        ShiftMaskKey::new(0xDEAD_BEEF_CAFE_1234)
    }

    fn make_engine(algo: ShiftMaskAlgo) -> Option<ShiftMaskEngine> {
        ShiftMaskEngine::new(make_key(), algo).ok()
    }

    #[test]
    fn test_platform_detection() {
        let p = PLATFORM_WIDTH;
        println!("✅ Platform: {}", p.name());
        assert!(p.name().len() > 0);
    }

    #[test]
    fn test_key_from_seed() {
        let k1 = ShiftMaskKey::from_seed("wasma.app");
        let k2 = ShiftMaskKey::from_seed("wasma.app");
        let k3 = ShiftMaskKey::from_seed("other.app");
        assert_eq!(k1.raw(), k2.raw());
        assert_ne!(k1.raw(), k3.raw());
        println!("✅ ShiftMaskKey from seed deterministic");
    }

    #[test]
    fn test_key_derive() {
        let k = make_key();
        let d1 = k.derive(0xA5);
        let d2 = k.derive(0xA5);
        let d3 = k.derive(0x01);
        assert_eq!(d1.raw(), d2.raw());
        assert_ne!(d1.raw(), d3.raw());
        println!("✅ ShiftMaskKey derive deterministic");
    }

    #[test]
    fn test_xor_id_roundtrip() {
        if let Some(engine) = make_engine(ShiftMaskAlgo::Xor) {
            for id in [0u64, 1, 0xFFFF_FFFF, u64::MAX, 0xDEAD_BEEF] {
                let masked = engine.mask_id(id);
                let back = engine.unmask_id(masked);
                assert_eq!(back, id, "XOR roundtrip failed for id={}", id);
            }
            println!("✅ XOR ID roundtrip working");
        }
    }

    #[test]
    fn test_bit_rotation_id_roundtrip() {
        if let Some(engine) = make_engine(ShiftMaskAlgo::BitRotation) {
            for id in [1u64, 42, 0x1234_5678_9ABC_DEF0, u64::MAX / 2] {
                let masked = engine.mask_id(id);
                let back = engine.unmask_id(masked);
                assert_eq!(back, id, "BitRotation roundtrip failed for id={}", id);
            }
            println!("✅ BitRotation ID roundtrip working");
        }
    }

    #[test]
    fn test_poly_id_masking() {
        if let Some(engine) = make_engine(ShiftMaskAlgo::PolynomialHash) {
            let id = 0x1234u64;
            let masked = engine.mask_id(id);
            assert_ne!(masked, id);
            println!("✅ PolynomialHash ID masking working: {} → {}", id, masked);
        }
    }

    #[test]
    fn test_lfsr_id_roundtrip() {
        if PLATFORM_WIDTH.is_full_support() {
            if let Some(engine) = make_engine(ShiftMaskAlgo::Lfsr) {
                for id in [1u64, 0xABCD_1234, u64::MAX] {
                    let masked = engine.mask_id(id);
                    let back = engine.unmask_id(masked);
                    assert_eq!(back, id);
                }
                println!("✅ LFSR ID roundtrip working (64-bit)");
            }
        } else {
            // LFSR must fail on 32-bit
            let result = ShiftMaskEngine::new(make_key(), ShiftMaskAlgo::Lfsr);
            assert!(matches!(result, Err(ShiftMaskError::SemiRestricted(_))));
            println!("✅ LFSR correctly blocked on 32-bit semi");
        }
    }

    #[test]
    fn test_xor_stream_roundtrip() {
        if let Some(engine) = make_engine(ShiftMaskAlgo::Xor) {
            let original = b"WASMA stream data test 1234567890";
            let mut data = original.to_vec();
            engine.mask_stream(&mut data);
            assert_ne!(data, original);
            engine.unmask_stream(&mut data);
            assert_eq!(data, original);
            println!("✅ XOR stream roundtrip working");
        }
    }

    #[test]
    fn test_rotation_stream_roundtrip() {
        if let Some(engine) = make_engine(ShiftMaskAlgo::BitRotation) {
            let original = vec![0xABu8; 64];
            let mut data = original.clone();
            engine.mask_stream(&mut data);
            engine.unmask_stream(&mut data);
            assert_eq!(data, original);
            println!("✅ BitRotation stream roundtrip working");
        }
    }

    #[test]
    fn test_window_id_escaper() {
        if let Some(engine) = make_engine(ShiftMaskAlgo::Xor) {
            let mut escaper = WindowIdEscaper::new(engine);
            let real_ids = [1u64, 2, 3, 100, 999];
            let masked: Vec<u64> = real_ids.iter().map(|&id| escaper.register(id)).collect();

            // All masked IDs distinct
            for i in 0..masked.len() {
                for j in i + 1..masked.len() {
                    assert_ne!(masked[i], masked[j]);
                }
            }
            // Resolve back
            for (i, &real) in real_ids.iter().enumerate() {
                assert_eq!(escaper.resolve(masked[i]), Some(real));
            }
            // Idempotent
            assert_eq!(escaper.register(real_ids[0]), masked[0]);
            println!(
                "✅ WindowIdEscaper working ({} windows)",
                escaper.registered_count()
            );
        }
    }

    #[test]
    fn test_stream_escaper() {
        if let Some(engine) = make_engine(ShiftMaskAlgo::Xor) {
            let escaper = StreamEscaper::new(engine);
            let original = b"test data stream";
            let masked = escaper.mask_copy(original);
            assert_ne!(masked, original);
            let mut back = masked.clone();
            escaper.unmask(&mut back);
            assert_eq!(back, original);
            println!("✅ StreamEscaper working");
        }
    }

    #[test]
    fn test_posix_window_esc_xor() {
        let config = make_config();
        let mut esc = PosixWindowEsc::from_config(&config, ShiftMaskAlgo::Xor).unwrap();

        let real_id = 42u64;
        let masked = esc.id_escaper.register(real_id);
        assert_ne!(masked, real_id);
        assert_eq!(esc.id_escaper.resolve(masked), Some(real_id));

        let data = b"hello world";
        let masked_data = esc.stream_escaper.mask_copy(data);
        assert_ne!(masked_data, data);

        esc.print_info();
        println!("✅ PosixWindowEsc (XOR) working");
    }

    #[test]
    fn test_posix_window_esc_auto() {
        let config = make_config();
        let esc = PosixWindowEsc::from_config_auto(&config);
        assert!(esc.is_ok());
        let esc = esc.unwrap();
        println!(
            "✅ PosixWindowEsc auto-algo: {}",
            esc.id_escaper.engine.algo().name()
        );
    }

    #[test]
    fn test_invalid_zero_key() {
        let key = ShiftMaskKey::new(0);
        // On 64-bit: key=0 is invalid; on 32-bit: effective=0 is also invalid
        let result = ShiftMaskEngine::new(key, ShiftMaskAlgo::Xor);
        assert!(matches!(result, Err(ShiftMaskError::InvalidKey)));
        println!("✅ Zero key correctly rejected");
    }

    #[test]
    fn test_mask_stream_copy_independent() {
        if let Some(engine) = make_engine(ShiftMaskAlgo::Xor) {
            let original = b"independent copy test";
            let copy = engine.mask_stream_copy(original);
            // Original unchanged
            assert_eq!(original, b"independent copy test");
            assert_ne!(copy.as_slice(), original.as_slice());
            println!("✅ mask_stream_copy does not modify original");
        }
    }
}