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des: tweak weak key test #468

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Feb 14, 2025
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des: tweak weak key test #468

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aa15367
des: tweak weak key test
newpavlov Feb 12, 2025
67d7440
tweak
newpavlov Feb 12, 2025
923ef32
Use macro to reduce number of `u64::from_ne_bytes`
newpavlov Feb 12, 2025
4bd3d51
minor code tweak
newpavlov Feb 12, 2025
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1 change: 0 additions & 1 deletion Cargo.lock
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1 change: 0 additions & 1 deletion des/Cargo.toml
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Expand Up @@ -14,7 +14,6 @@ categories = ["cryptography", "no-std"]

[dependencies]
cipher = "=0.5.0-pre.7"
subtle = { version = "2.6", default-features = false }

[dev-dependencies]
cipher = { version = "=0.5.0-pre.7", features = ["dev"] }
Expand Down
73 changes: 73 additions & 0 deletions des/src/consts.rs
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Expand Up @@ -57,3 +57,76 @@ pub const SBOXES: [[u8; 64]; 8] = [
0, 15, 6, 12, 10, 9, 13, 0, 15, 3, 3, 5, 5, 6, 8, 11,
],
];

macro_rules! as_ne_u64 {
[$($key:expr,)*] => {
[$(u64::from_ne_bytes($key),)*]
};
}

pub(crate) static WEAK_KEYS: &[u64; 64] = &as_ne_u64![
[0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01],
[0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE],
[0xE0, 0xE0, 0xE0, 0xE0, 0xF1, 0xF1, 0xF1, 0xF1],
[0x1F, 0x1F, 0x1F, 0x1F, 0x0E, 0x0E, 0x0E, 0x0E],
[0x01, 0x1F, 0x01, 0x1F, 0x01, 0x0E, 0x01, 0x0E],
[0x1F, 0x01, 0x1F, 0x01, 0x0E, 0x01, 0x0E, 0x01],
[0x01, 0xE0, 0x01, 0xE0, 0x01, 0xF1, 0x01, 0xF1],
[0xE0, 0x01, 0xE0, 0x01, 0xF1, 0x01, 0xF1, 0x01],
[0x01, 0xFE, 0x01, 0xFE, 0x01, 0xFE, 0x01, 0xFE],
[0xFE, 0x01, 0xFE, 0x01, 0xFE, 0x01, 0xFE, 0x01],
[0x1F, 0xE0, 0x1F, 0xE0, 0x0E, 0xF1, 0x0E, 0xF1],
[0xE0, 0x1F, 0xE0, 0x1F, 0xF1, 0x0E, 0xF1, 0x0E],
[0x1F, 0xFE, 0x1F, 0xFE, 0x0E, 0xFE, 0x0E, 0xFE],
[0xFE, 0x1F, 0xFE, 0x1F, 0xFE, 0x0E, 0xFE, 0x0E],
[0xE0, 0xFE, 0xE0, 0xFE, 0xF1, 0xFE, 0xF1, 0xFE],
[0xFE, 0xE0, 0xFE, 0xE0, 0xFE, 0xF1, 0xFE, 0xF1],
[0x01, 0x01, 0x1F, 0x1F, 0x01, 0x01, 0x0E, 0x0E],
[0x1F, 0x1F, 0x01, 0x01, 0x0E, 0x0E, 0x01, 0x01],
[0xE0, 0xE0, 0x1F, 0x1F, 0xF1, 0xF1, 0x0E, 0x0E],
[0x01, 0x01, 0xE0, 0xE0, 0x01, 0x01, 0xF1, 0xF1],
[0x1F, 0x1F, 0xE0, 0xE0, 0x0E, 0x0E, 0xF1, 0xF1],
[0xE0, 0xE0, 0xFE, 0xFE, 0xF1, 0xF1, 0xFE, 0xFE],
[0x01, 0x01, 0xFE, 0xFE, 0x01, 0x01, 0xFE, 0xFE],
[0x1F, 0x1F, 0xFE, 0xFE, 0x0E, 0x0E, 0xFE, 0xFE],
[0xE0, 0xFE, 0x01, 0x1F, 0xF1, 0xFE, 0x01, 0x0E],
[0x01, 0x1F, 0x1F, 0x01, 0x01, 0x0E, 0x0E, 0x01],
[0x1F, 0xE0, 0x01, 0xFE, 0x0E, 0xF1, 0x01, 0xFE],
[0xE0, 0xFE, 0x1F, 0x01, 0xF1, 0xFE, 0x0E, 0x01],
[0x01, 0x1F, 0xE0, 0xFE, 0x01, 0x0E, 0xF1, 0xFE],
[0x1F, 0xE0, 0xE0, 0x1F, 0x0E, 0xF1, 0xF1, 0x0E],
[0xE0, 0xFE, 0xFE, 0xE0, 0xF1, 0xFE, 0xFE, 0xF1],
[0x01, 0x1F, 0xFE, 0xE0, 0x01, 0x0E, 0xFE, 0xF1],
[0x1F, 0xE0, 0xFE, 0x01, 0x0E, 0xF1, 0xFE, 0x01],
[0xFE, 0x01, 0x01, 0xFE, 0xFE, 0x01, 0x01, 0xFE],
[0x01, 0xE0, 0x1F, 0xFE, 0x01, 0xF1, 0x0E, 0xFE],
[0x1F, 0xFE, 0x01, 0xE0, 0x0E, 0xFE, 0x01, 0xF1],
[0xFE, 0x01, 0x1F, 0xE0, 0xFE, 0x01, 0x0E, 0xF1],
[0xFE, 0x01, 0xE0, 0x1F, 0xFE, 0x01, 0xF1, 0x0E],
[0x1F, 0xFE, 0xE0, 0x01, 0x0E, 0xFE, 0xF1, 0x01],
[0xFE, 0x1F, 0x01, 0xE0, 0xFE, 0x0E, 0x01, 0xF1],
[0x01, 0xE0, 0xE0, 0x01, 0x01, 0xF1, 0xF1, 0x01],
[0x1F, 0xFE, 0xFE, 0x1F, 0x0E, 0xFE, 0xFE, 0x0E],
[0xFE, 0x1F, 0xE0, 0x01, 0xFE, 0x0E, 0xF1, 0x01],
[0x01, 0xE0, 0xFE, 0x1F, 0x01, 0xF1, 0xFE, 0x0E],
[0xE0, 0x01, 0x01, 0xE0, 0xF1, 0x01, 0x01, 0xF1],
[0xFE, 0x1F, 0x1F, 0xFE, 0xFE, 0x0E, 0x0E, 0xFE],
[0x01, 0xFE, 0x1F, 0xE0, 0x01, 0xFE, 0x0E, 0xF1],
[0xE0, 0x01, 0x1F, 0xFE, 0xF1, 0x01, 0x0E, 0xFE],
[0xFE, 0xE0, 0x01, 0x1F, 0xFE, 0xF1, 0x01, 0x0E],
[0x01, 0xFE, 0xE0, 0x1F, 0x01, 0xFE, 0xF1, 0x0E],
[0xE0, 0x01, 0xFE, 0x1F, 0xF1, 0x01, 0xFE, 0x0E],
[0xFE, 0xE0, 0x1F, 0x01, 0xFE, 0xF1, 0x0E, 0x01],
[0x01, 0xFE, 0xFE, 0x01, 0x01, 0xFE, 0xFE, 0x01],
[0xE0, 0x1F, 0x01, 0xFE, 0xF1, 0x0E, 0x01, 0xFE],
[0xFE, 0xE0, 0xE0, 0xFE, 0xFE, 0xF1, 0xF1, 0xFE],
[0x1F, 0x01, 0x01, 0x1F, 0x0E, 0x01, 0x01, 0x0E],
[0xE0, 0x1F, 0x1F, 0xE0, 0xF1, 0x0E, 0x0E, 0xF1],
[0xFE, 0xFE, 0x01, 0x01, 0xFE, 0xFE, 0x01, 0x01],
[0x1F, 0x01, 0xE0, 0xFE, 0x0E, 0x01, 0xF1, 0xFE],
[0xE0, 0x1F, 0xFE, 0x01, 0xF1, 0x0E, 0xFE, 0x01],
[0xFE, 0xFE, 0x1F, 0x1F, 0xFE, 0xFE, 0x0E, 0x0E],
[0x1F, 0x01, 0xFE, 0xE0, 0x0E, 0x01, 0xFE, 0xF1],
[0xE0, 0xE0, 0x01, 0x01, 0xF1, 0xF1, 0x01, 0x01],
[0xFE, 0xFE, 0xE0, 0xE0, 0xFE, 0xFE, 0xF1, 0xF1],
];
81 changes: 3 additions & 78 deletions des/src/des.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,6 @@ use cipher::{
KeyInit, KeySizeUser, ParBlocksSizeUser,
};
use core::fmt;
use subtle::{Choice, ConstantTimeEq};

#[cfg(feature = "zeroize")]
use cipher::zeroize::{Zeroize, ZeroizeOnDrop};
Expand Down Expand Up @@ -45,73 +44,6 @@ impl KeySizeUser for Des {
type KeySize = U8;
}

static WEAK_KEYS: [[u8; 8]; 64] = [
[0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01],
[0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE],
[0xE0, 0xE0, 0xE0, 0xE0, 0xF1, 0xF1, 0xF1, 0xF1],
[0x1F, 0x1F, 0x1F, 0x1F, 0x0E, 0x0E, 0x0E, 0x0E],
[0x01, 0x1F, 0x01, 0x1F, 0x01, 0x0E, 0x01, 0x0E],
[0x1F, 0x01, 0x1F, 0x01, 0x0E, 0x01, 0x0E, 0x01],
[0x01, 0xE0, 0x01, 0xE0, 0x01, 0xF1, 0x01, 0xF1],
[0xE0, 0x01, 0xE0, 0x01, 0xF1, 0x01, 0xF1, 0x01],
[0x01, 0xFE, 0x01, 0xFE, 0x01, 0xFE, 0x01, 0xFE],
[0xFE, 0x01, 0xFE, 0x01, 0xFE, 0x01, 0xFE, 0x01],
[0x1F, 0xE0, 0x1F, 0xE0, 0x0E, 0xF1, 0x0E, 0xF1],
[0xE0, 0x1F, 0xE0, 0x1F, 0xF1, 0x0E, 0xF1, 0x0E],
[0x1F, 0xFE, 0x1F, 0xFE, 0x0E, 0xFE, 0x0E, 0xFE],
[0xFE, 0x1F, 0xFE, 0x1F, 0xFE, 0x0E, 0xFE, 0x0E],
[0xE0, 0xFE, 0xE0, 0xFE, 0xF1, 0xFE, 0xF1, 0xFE],
[0xFE, 0xE0, 0xFE, 0xE0, 0xFE, 0xF1, 0xFE, 0xF1],
[0x01, 0x01, 0x1F, 0x1F, 0x01, 0x01, 0x0E, 0x0E],
[0x1F, 0x1F, 0x01, 0x01, 0x0E, 0x0E, 0x01, 0x01],
[0xE0, 0xE0, 0x1F, 0x1F, 0xF1, 0xF1, 0x0E, 0x0E],
[0x01, 0x01, 0xE0, 0xE0, 0x01, 0x01, 0xF1, 0xF1],
[0x1F, 0x1F, 0xE0, 0xE0, 0x0E, 0x0E, 0xF1, 0xF1],
[0xE0, 0xE0, 0xFE, 0xFE, 0xF1, 0xF1, 0xFE, 0xFE],
[0x01, 0x01, 0xFE, 0xFE, 0x01, 0x01, 0xFE, 0xFE],
[0x1F, 0x1F, 0xFE, 0xFE, 0x0E, 0x0E, 0xFE, 0xFE],
[0xE0, 0xFE, 0x01, 0x1F, 0xF1, 0xFE, 0x01, 0x0E],
[0x01, 0x1F, 0x1F, 0x01, 0x01, 0x0E, 0x0E, 0x01],
[0x1F, 0xE0, 0x01, 0xFE, 0x0E, 0xF1, 0x01, 0xFE],
[0xE0, 0xFE, 0x1F, 0x01, 0xF1, 0xFE, 0x0E, 0x01],
[0x01, 0x1F, 0xE0, 0xFE, 0x01, 0x0E, 0xF1, 0xFE],
[0x1F, 0xE0, 0xE0, 0x1F, 0x0E, 0xF1, 0xF1, 0x0E],
[0xE0, 0xFE, 0xFE, 0xE0, 0xF1, 0xFE, 0xFE, 0xF1],
[0x01, 0x1F, 0xFE, 0xE0, 0x01, 0x0E, 0xFE, 0xF1],
[0x1F, 0xE0, 0xFE, 0x01, 0x0E, 0xF1, 0xFE, 0x01],
[0xFE, 0x01, 0x01, 0xFE, 0xFE, 0x01, 0x01, 0xFE],
[0x01, 0xE0, 0x1F, 0xFE, 0x01, 0xF1, 0x0E, 0xFE],
[0x1F, 0xFE, 0x01, 0xE0, 0x0E, 0xFE, 0x01, 0xF1],
[0xFE, 0x01, 0x1F, 0xE0, 0xFE, 0x01, 0x0E, 0xF1],
[0xFE, 0x01, 0xE0, 0x1F, 0xFE, 0x01, 0xF1, 0x0E],
[0x1F, 0xFE, 0xE0, 0x01, 0x0E, 0xFE, 0xF1, 0x01],
[0xFE, 0x1F, 0x01, 0xE0, 0xFE, 0x0E, 0x01, 0xF1],
[0x01, 0xE0, 0xE0, 0x01, 0x01, 0xF1, 0xF1, 0x01],
[0x1F, 0xFE, 0xFE, 0x1F, 0x0E, 0xFE, 0xFE, 0x0E],
[0xFE, 0x1F, 0xE0, 0x01, 0xFE, 0x0E, 0xF1, 0x01],
[0x01, 0xE0, 0xFE, 0x1F, 0x01, 0xF1, 0xFE, 0x0E],
[0xE0, 0x01, 0x01, 0xE0, 0xF1, 0x01, 0x01, 0xF1],
[0xFE, 0x1F, 0x1F, 0xFE, 0xFE, 0x0E, 0x0E, 0xFE],
[0x01, 0xFE, 0x1F, 0xE0, 0x01, 0xFE, 0x0E, 0xF1],
[0xE0, 0x01, 0x1F, 0xFE, 0xF1, 0x01, 0x0E, 0xFE],
[0xFE, 0xE0, 0x01, 0x1F, 0xFE, 0xF1, 0x01, 0x0E],
[0x01, 0xFE, 0xE0, 0x1F, 0x01, 0xFE, 0xF1, 0x0E],
[0xE0, 0x01, 0xFE, 0x1F, 0xF1, 0x01, 0xFE, 0x0E],
[0xFE, 0xE0, 0x1F, 0x01, 0xFE, 0xF1, 0x0E, 0x01],
[0x01, 0xFE, 0xFE, 0x01, 0x01, 0xFE, 0xFE, 0x01],
[0xE0, 0x1F, 0x01, 0xFE, 0xF1, 0x0E, 0x01, 0xFE],
[0xFE, 0xE0, 0xE0, 0xFE, 0xFE, 0xF1, 0xF1, 0xFE],
[0x1F, 0x01, 0x01, 0x1F, 0x0E, 0x01, 0x01, 0x0E],
[0xE0, 0x1F, 0x1F, 0xE0, 0xF1, 0x0E, 0x0E, 0xF1],
[0xFE, 0xFE, 0x01, 0x01, 0xFE, 0xFE, 0x01, 0x01],
[0x1F, 0x01, 0xE0, 0xFE, 0x0E, 0x01, 0xF1, 0xFE],
[0xE0, 0x1F, 0xFE, 0x01, 0xF1, 0x0E, 0xFE, 0x01],
[0xFE, 0xFE, 0x1F, 0x1F, 0xFE, 0xFE, 0x0E, 0x0E],
[0x1F, 0x01, 0xFE, 0xE0, 0x0E, 0x01, 0xFE, 0xF1],
[0xE0, 0xE0, 0x01, 0x01, 0xF1, 0xF1, 0x01, 0x01],
[0xFE, 0xFE, 0xE0, 0xE0, 0xFE, 0xFE, 0xF1, 0xF1],
];

impl KeyInit for Des {
#[inline]
fn new(key: &Key<Self>) -> Self {
Expand All @@ -121,16 +53,9 @@ impl KeyInit for Des {

#[inline]
fn weak_key_test(key: &Key<Self>) -> Result<(), WeakKeyError> {
let mut weak = Choice::from(0);

for weak_key in &WEAK_KEYS {
weak |= key.ct_eq(weak_key);
}

if weak.unwrap_u8() == 0 {
Ok(())
} else {
Err(WeakKeyError)
match super::weak_key_test(&key.0) {
0 => Ok(()),
_ => Err(WeakKeyError),
}
}
}
Expand Down
12 changes: 12 additions & 0 deletions des/src/lib.rs
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Expand Up @@ -30,3 +30,15 @@ mod utils;

pub use crate::des::Des;
pub use crate::tdes::{TdesEde2, TdesEde3, TdesEee2, TdesEee3};

/// Checks whether the key is weak.
///
/// Returns 1 if the key is weak; otherwise, returns 0.
fn weak_key_test(key: &[u8; 8]) -> u8 {
let key = u64::from_ne_bytes(*key);
let mut is_weak = 0u8;
for &weak_key in crate::consts::WEAK_KEYS {
is_weak |= u8::from(key == weak_key);
}
is_weak
}
43 changes: 15 additions & 28 deletions des/src/tdes.rs
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Expand Up @@ -12,36 +12,23 @@ use cipher::{
use core::fmt;

#[cfg(feature = "zeroize")]
use cipher::zeroize::{ZeroizeOnDrop, Zeroizing};
use cipher::zeroize::ZeroizeOnDrop;

#[inline]
fn weak_key_test<const SIZE: usize, U: KeyInit>(key: &Key<U>) -> Result<(), WeakKeyError> {
#[cfg(feature = "zeroize")]
let mut tmp = Zeroizing::new(Key::<U>::default());
#[cfg(not(feature = "zeroize"))]
let mut tmp = Key::<U>::default();
fn weak_key_test(key: &[u8]) -> Result<(), WeakKeyError> {
let sub_key_size = <Des as KeySizeUser>::KeySize::USIZE;
assert_eq!(key.len() % sub_key_size, 0);

for i in 0..<U as KeySizeUser>::KeySize::USIZE {
// count number of set bits in byte, excluding the low-order bit - SWAR method
let mut c = key[i] & 0xFE;

c = (c & 0x55) + ((c >> 1) & 0x55);
c = (c & 0x33) + ((c >> 2) & 0x33);
c = (c & 0x0F) + ((c >> 4) & 0x0F);

// if count is even, set low key bit to 1, otherwise 0
tmp[i] = (key[i] & 0xFE) | u8::from(c & 0x01 != 0x01);
let mut is_weak = 0u8;
for des_key in key.chunks_exact(sub_key_size) {
let des_key = des_key.try_into().unwrap();
is_weak |= super::weak_key_test(des_key);
}

let mut des_key = Key::<Des>::default();
for i in 0..SIZE {
des_key.copy_from_slice(
&tmp.as_slice()[i * <Des as KeySizeUser>::KeySize::USIZE
..(i + 1) * <Des as KeySizeUser>::KeySize::USIZE],
);
Des::weak_key_test(&des_key)?;
match is_weak {
0 => Ok(()),
_ => Err(WeakKeyError),
}
Ok(())
}

/// Triple DES (3DES) block cipher.
Expand Down Expand Up @@ -70,7 +57,7 @@ impl KeyInit for TdesEde3 {

#[inline]
fn weak_key_test(key: &Key<Self>) -> Result<(), WeakKeyError> {
weak_key_test::<3, Self>(key)
weak_key_test(key)
}
}

Expand Down Expand Up @@ -159,7 +146,7 @@ impl KeyInit for TdesEee3 {

#[inline]
fn weak_key_test(key: &Key<Self>) -> Result<(), WeakKeyError> {
weak_key_test::<3, Self>(key)
weak_key_test(key)
}
}

Expand Down Expand Up @@ -245,7 +232,7 @@ impl KeyInit for TdesEde2 {

#[inline]
fn weak_key_test(key: &Key<Self>) -> Result<(), WeakKeyError> {
weak_key_test::<2, Self>(key)
weak_key_test(key)
}
}

Expand Down Expand Up @@ -331,7 +318,7 @@ impl KeyInit for TdesEee2 {

#[inline]
fn weak_key_test(key: &Key<Self>) -> Result<(), WeakKeyError> {
weak_key_test::<2, Self>(key)
weak_key_test(key)
}
}

Expand Down