james/yubikey.rs
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mgm: use TdesEde3::weak_key_test (#621)

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Replaces the vendored weak key test with the upstream one from the `des`
crate which was added in RustCrypto/block-ciphers#465
This commit is contained in:
Tony Arcieri (iqlusion)
2025-08-13 15:36:53 -06:00
committed by GitHub
parent 7f2b423713
commit b4be1bb216
2 changed files with 7 additions and 75 deletions
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src/mgm.rs
+7 -5
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@@ -70,12 +70,14 @@ pub(crate) const APPLET_NAME: &str = "YubiKey MGMT";
#[cfg(feature = "untested")]
pub(crate) const APPLET_ID: &[u8] = &[0xa0, 0x00, 0x00, 0x05, 0x27, 0x47, 0x11, 0x17];
mod tdes;
pub(crate) use tdes::DES_LEN_3DES;
use tdes::DES_LEN_DES;
pub(crate) const ADMIN_FLAGS_1_PROTECTED_MGM: u8 = 0x02;
/// Size of a DES key
pub(super) const DES_LEN_DES: usize = 8;
/// Size of a 3DES key
pub(crate) const DES_LEN_3DES: usize = DES_LEN_DES * 3;
#[cfg(feature = "untested")]
const CB_ADMIN_SALT: usize = 16;
@@ -172,7 +174,7 @@ impl MgmKey {
///
/// Returns an error if the key is weak.
pub fn new(key_bytes: [u8; DES_LEN_3DES]) -> Result<Self> {
if tdes::is_weak_key(&key_bytes) {
if TdesEde3::weak_key_test(key_bytes.as_ref()).is_err() {
error!(
"blacklisting key '{:?}' since it's weak (with odd parity)",
&key_bytes
src/mgm/tdes.rs
-70
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@@ -1,70 +0,0 @@
use zeroize::Zeroizing;
/// Size of a DES key
pub(super) const DES_LEN_DES: usize = 8;
/// Size of a 3DES key
pub(crate) const DES_LEN_3DES: usize = DES_LEN_DES * 3;
/// Weak and semi weak DES keys as taken from:
/// %A D.W. Davies
/// %A W.L. Price
/// %T Security for Computer Networks
/// %I John Wiley & Sons
/// %D 1984
const WEAK_DES_KEYS: &[[u8; DES_LEN_DES]] = &[
// weak keys
[0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01],
[0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE],
[0x1F, 0x1F, 0x1F, 0x1F, 0x0E, 0x0E, 0x0E, 0x0E],
[0xE0, 0xE0, 0xE0, 0xE0, 0xF1, 0xF1, 0xF1, 0xF1],
// semi-weak keys
[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],
[0x01, 0xE0, 0x01, 0xE0, 0x01, 0xF1, 0x01, 0xF1],
[0xE0, 0x01, 0xE0, 0x01, 0xF1, 0x01, 0xF1, 0x01],
[0x1F, 0xFE, 0x1F, 0xFE, 0x0E, 0xFE, 0x0E, 0xFE],
[0xFE, 0x1F, 0xFE, 0x1F, 0xFE, 0x0E, 0xFE, 0x0E],
[0x01, 0x1F, 0x01, 0x1F, 0x01, 0x0E, 0x01, 0x0E],
[0x1F, 0x01, 0x1F, 0x01, 0x0E, 0x01, 0x0E, 0x01],
[0xE0, 0xFE, 0xE0, 0xFE, 0xF1, 0xFE, 0xF1, 0xFE],
[0xFE, 0xE0, 0xFE, 0xE0, 0xFE, 0xF1, 0xFE, 0xF1],
];
/// Is this 3DES key weak?
///
/// This check is performed automatically when the key is instantiated to
/// ensure no such keys are used.
pub(super) fn is_weak_key(key: &[u8; DES_LEN_3DES]) -> bool {
// set odd parity of key
let mut tmp = Zeroizing::new([0u8; DES_LEN_3DES]);
for i in 0..DES_LEN_3DES {
// 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);
}
// check odd parity key against table by DES key block
let mut is_weak = false;
for weak_key in WEAK_DES_KEYS.iter() {
if weak_key == &tmp[0..DES_LEN_DES]
|| weak_key == &tmp[DES_LEN_DES..2 * DES_LEN_DES]
|| weak_key == &tmp[2 * DES_LEN_DES..3 * DES_LEN_DES]
{
is_weak = true;
break;
}
}
is_weak
}