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Refactoring #16

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Sep 2, 2020
Merged

Refactoring #16

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146 changes: 49 additions & 97 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,62 +14,42 @@ use core::{char, fmt, mem, ptr, str};
///
/// Supported types are `u8`, `u16`, `u32`, `u64`, `usize`, `i8`, `i16`, `i32`, `i64`, `isize`, `bool`, `f32` and `f64`.
///
/// If no type is specified then type inference picks one of the supported types.
///
/// The integer types generate a random value in their respective range.
/// The float types generate a random value in range of `[1.0, 2.0)`.
///
/// While the result is generated at compiletime only the integer types are available in const contexts.
///
/// Note that the seed _must_ be a uniformly distributed random `u64` value.
/// If such a value is not available, see the [`splitmix`](fn.splitmix.html) function to generate it from non uniform random value.
///
/// ```
/// // Explicit type
/// const RND: i32 = obfstr::random!(u8) as i32;
/// assert!(RND >= 0 && RND <= 255);
///
/// // Inferred type
/// let rnd: f32 = obfstr::random!();
/// assert!(rnd >= 1.0 && rnd < 2.0);
/// ```
#[macro_export]
macro_rules! random {
(u8) => { $crate::random!(u64) as u8 };
(u16) => { $crate::random!(u64) as u16 };
(u32) => { $crate::random!(u64) as u32 };
(u64) => {{ const ENTROPY: u64 = $crate::entropy(file!(), line!(), column!()); ENTROPY }};
(usize) => { $crate::random!(u64) as usize };
(i8) => { $crate::random!(u64) as i8 };
(i16) => { $crate::random!(u64) as i16 };
(i32) => { $crate::random!(u64) as i32 };
(i64) => { $crate::random!(u64) as i64 };
(isize) => { $crate::random!(u64) as isize };
(bool) => { $crate::random!(u64) & 1 != 0 };
(f32) => { <f32 as $crate::Random>::random($crate::random!(u64)) };
(f64) => { <f64 as $crate::Random>::random($crate::random!(u64)) };
($_:ident) => { compile_error!(concat!("unsupported type: ", stringify!($_))) };
() => { $crate::Random::random($crate::random!(u64)) };
}

#[doc(hidden)]
pub trait Random {
fn random(seed: u64) -> Self;
}

impl Random for u8 { #[inline] fn random(seed: u64) -> u8 { seed as u8 } }
impl Random for u16 { #[inline] fn random(seed: u64) -> u16 { seed as u16 } }
impl Random for u32 { #[inline] fn random(seed: u64) -> u32 { seed as u32 } }
impl Random for u64 { #[inline] fn random(seed: u64) -> u64 { seed } }

impl Random for i8 { #[inline] fn random(seed: u64) -> i8 { seed as i8 } }
impl Random for i16 { #[inline] fn random(seed: u64) -> i16 { seed as i16 } }
impl Random for i32 { #[inline] fn random(seed: u64) -> i32 { seed as i32 } }
impl Random for i64 { #[inline] fn random(seed: u64) -> i64 { seed as i64 } }

impl Random for bool { #[inline] fn random(seed: u64) -> bool { seed & 1 != 0 } }

impl Random for f32 { #[inline] fn random(seed: u64) -> f32 { f32::from_bits(0b0_01111111 << (f32::MANTISSA_DIGITS - 1) | (seed as u32 >> 9)) } }
impl Random for f64 { #[inline] fn random(seed: u64) -> f64 { f64::from_bits(0b0_01111111111 << (f64::MANTISSA_DIGITS - 1) | (seed >> 12)) } }

/// Compiletime RNG.
($ty:ident) => {{ const ENTROPY: u64 = $crate::entropy(file!(), line!(), column!()); $crate::random!($ty, ENTROPY) }};

(u8, $seed:expr) => { $seed as u8 };
(u16, $seed:expr) => { $seed as u16 };
(u32, $seed:expr) => { $seed as u32 };
(u64, $seed:expr) => { $seed as u64 };
(usize, $seed:expr) => { $seed as usize };
(i8, $seed:expr) => { $seed as i8 };
(i16, $seed:expr) => { $seed as i16 };
(i32, $seed:expr) => { $seed as i32 };
(i64, $seed:expr) => { $seed as i64 };
(isize, $seed:expr) => { $seed as isize };
(bool, $seed:expr) => { $seed as i64 >= 0 };
(f32, $seed:expr) => { f32::from_bits(0b0_01111111 << (f32::MANTISSA_DIGITS - 1) | ($seed as u32 >> 9)) };
(f64, $seed:expr) => { f64::from_bits(0b0_01111111111 << (f64::MANTISSA_DIGITS - 1) | ($seed >> 12)) };
($_:ident, $seed:expr) => { compile_error!(concat!("unsupported type: ", stringify!($_))) };
}

/// Compiletime bitmixing.
///
/// Takes an intermediate hash that may not be thoroughly mixed and increase its entropy to obtain both better distribution.
/// See [Better Bit Mixing](https://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html) for reference.
#[inline(always)]
pub const fn splitmix(seed: u64) -> u64 {
let next = seed.wrapping_add(0x9e3779b97f4a7c15);
Expand All @@ -80,6 +60,8 @@ pub const fn splitmix(seed: u64) -> u64 {
}

/// Compiletime string hash.
///
/// Implemented using the [DJB2 hash function](http://www.cse.yorku.ca/~oz/hash.html#djb2).
#[inline(always)]
pub const fn hash(s: &str) -> u32 {
let s = s.as_bytes();
Expand All @@ -98,8 +80,7 @@ pub const fn hash(s: &str) -> u32 {
///
/// ```
/// const STRING: &str = "Hello World";
/// const HASH: u32 = obfstr::hash!(STRING);
/// assert_eq!(HASH, 1481604729);
/// assert_eq!(obfstr::hash!(STRING), 1481604729);
/// ```
#[macro_export]
macro_rules! hash {
Expand All @@ -110,7 +91,7 @@ macro_rules! hash {
#[doc(hidden)]
#[inline(always)]
pub const fn entropy(file: &str, line: u32, column: u32) -> u64 {
splitmix(SEED ^ (hash(file) as u64 ^ (line as u64).rotate_left(32) ^ (column as u64).rotate_left(48)))
splitmix(splitmix(splitmix(SEED ^ hash(file) as u64) ^ line as u64) ^ column as u64)
}

/// Compiletime RNG seed.
Expand Down Expand Up @@ -270,8 +251,9 @@ impl<const LEN: usize> ObfString<[u8; LEN]> {
}
ObfString { key, data }
}
#[doc(hidden)]
#[inline(always)]
fn eq(&self, s: &str, x: usize) -> bool {
pub fn eq(&self, s: &str, x: usize) -> bool {
if LEN != s.len() {
return false;
}
Expand All @@ -282,26 +264,6 @@ impl<const LEN: usize> ObfString<[u8; LEN]> {
}
}
}
impl<const LEN: usize> PartialEq<str> for ObfString<[u8; LEN]> {
fn eq(&self, other: &str) -> bool {
self.eq(other, random!(usize) & 0xffff)
}
}
impl<const LEN: usize> PartialEq<ObfString<[u8; LEN]>> for str {
fn eq(&self, other: &ObfString<[u8; LEN]>) -> bool {
other.eq(self, random!(usize) & 0xffff)
}
}
impl<const LEN: usize> PartialEq<ObfString<[u8; LEN]>> for &str {
fn eq(&self, other: &ObfString<[u8; LEN]>) -> bool {
other.eq(*self, random!(usize) & 0xffff)
}
}
impl<const LEN: usize> fmt::Debug for ObfString<[u8; LEN]> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
self.deobfuscate(random!(usize) & 0xffff).fmt(f)
}
}

#[inline(never)]
unsafe fn decryptbuf(dest: *mut u8, src: *const u8, len: usize) {
Expand All @@ -327,7 +289,7 @@ unsafe fn decrypteq(obfstr: *const u8, clearstr: *const u8, len: usize) -> bool

impl<const LEN: usize> ObfBuffer<[u8; LEN]> {
#[inline]
pub fn as_slice(&self) -> &[u8] {
pub const fn as_slice(&self) -> &[u8] {
&self.0
}
#[inline]
Expand Down Expand Up @@ -386,8 +348,9 @@ impl<const LEN: usize> ObfString<[u16; LEN]> {
}
ObfString { key, data }
}
#[doc(hidden)]
#[inline(always)]
fn eq(&self, s: &[u16], x: usize) -> bool {
pub fn eq(&self, s: &[u16], x: usize) -> bool {
if LEN != s.len() {
return false;
}
Expand All @@ -398,31 +361,6 @@ impl<const LEN: usize> ObfString<[u16; LEN]> {
}
}
}
impl<const LEN: usize> PartialEq<[u16]> for ObfString<[u16; LEN]> {
fn eq(&self, other: &[u16]) -> bool {
self.eq(other, random!(usize) & 0xffff)
}
}
impl<const LEN: usize> PartialEq<ObfString<[u16; LEN]>> for [u16] {
fn eq(&self, other: &ObfString<[u16; LEN]>) -> bool {
other.eq(self, random!(usize) & 0xffff)
}
}
impl<const LEN: usize> PartialEq<ObfString<[u16; LEN]>> for &[u16] {
fn eq(&self, other: &ObfString<[u16; LEN]>) -> bool {
other.eq(*self, random!(usize) & 0xffff)
}
}
impl<const LEN: usize> PartialEq<ObfString<[u16; LEN]>> for [u16; LEN] {
fn eq(&self, other: &ObfString<[u16; LEN]>) -> bool {
other.eq(self, random!(usize) & 0xffff)
}
}
impl<const LEN: usize> PartialEq<ObfString<[u16; LEN]>> for &[u16; LEN] {
fn eq(&self, other: &ObfString<[u16; LEN]>) -> bool {
other.eq(*self, random!(usize) & 0xffff)
}
}
impl<const LEN: usize> fmt::Debug for ObfString<[u16; LEN]> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
self.deobfuscate(random!(usize) & 0xffff).fmt(f)
Expand Down Expand Up @@ -453,7 +391,7 @@ unsafe fn wdecrypteq(obfstr: *const u16, clearstr: *const u16, len: usize) -> bo

impl<const LEN: usize> ObfBuffer<[u16; LEN]> {
#[inline]
pub fn as_slice(&self) -> &[u16] {
pub const fn as_slice(&self) -> &[u16] {
&self.0
}
}
Expand Down Expand Up @@ -516,3 +454,17 @@ macro_rules! obfconst {
($s:literal) => {{ const STRING: $crate::ObfString<[u8; {$s.len()}]> = $crate::ObfString::<[u8; {$s.len()}]>::obfuscate($crate::random!(u32), $s); STRING }};
(L$s:literal) => {{ const STRING: $crate::ObfString<[u16; {$crate::wide_len($s)}]> = $crate::ObfString::<[u16; {$crate::wide_len($s)}]>::obfuscate($crate::random!(u32), $s); STRING }};
}

/// Check if string equals specific string literal.
///
/// This does not need to decrypt the string before comparison and the comparison is not constant-time.
///
/// ```
/// let e = "Hello 🌍";
/// assert!(obfstr::obfeq!(e, "Hello 🌍"));
/// ```
#[macro_export]
macro_rules! obfeq {
($e:expr, $s:literal) => { $crate::obfconst!($s).eq(&$e, $crate::random!(usize) & 0xffff) };
($e:expr, L$s:literal) => { $crate::obfconst!(L$s).eq($e, $crate::random!(usize) & 0xffff) };
}
7 changes: 2 additions & 5 deletions tests/main.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,9 +6,6 @@ fn main() {
let (a, b) = (random!(u64), random!(u64));
assert_ne!(a, b);

assert_eq!(obfstr!("Hello world"), "Hello world");
assert_eq!("Hello world", obfconst!("Hello world"));

assert_eq!(
obfstr!("This literal is very very very long to see if it correctly handles long string"),
"This literal is very very very long to see if it correctly handles long string");
Expand All @@ -19,6 +16,6 @@ fn main() {
assert_eq!(obfstr!(L"ABC"), &[b'A' as u16, b'B' as u16, b'C' as u16]);
assert_eq!(obfstr!(L"🌍"), &[0xd83c, 0xdf0d]);

assert_eq!(wide!("ABC"), obfconst!(L"ABC"));
assert_eq!(wide!("🌍"), obfconst!(L"🌍"));
assert!(obfeq!(wide!("ABC"), L"ABC"));
assert!(obfeq!(wide!("🌍"), L"🌍"));
}