kristoferssolo/des-rs
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feat: finish pc1 implementation

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Kristofers Solo 2025-10-01 16:41:52 +03:00
parent 6cda261f0f
commit 1d099406c7
Signed by: kristoferssolo
GPG Key ID: 8687F2D3EEE6F0ED
1 changed files with 20 additions and 7 deletions
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src/lib.rs
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@ -55,7 +55,7 @@ impl Des {
for (idx, &shift_num) in ROUND_ROTATIONS.iter().enumerate() { for (idx, &shift_num) in ROUND_ROTATIONS.iter().enumerate() {
left = shift(left, shift_num); left = shift(left, shift_num);
right = shift(right, shift_num); right = shift(right, shift_num);
let combined = (u64::from(right) << 28) | u64::from(left); let combined = contatinate_keys(left, right);
let subkey = pc2(combined); let subkey = pc2(combined);
self.subkeys[idx] = subkey; self.subkeys[idx] = subkey;
} }
@ -95,10 +95,9 @@ pub fn pc1(key: u64) -> u64 {
.fold(0, |mut acc, (idx, &pos)| { .fold(0, |mut acc, (idx, &pos)| {
// pos is 1-based DES bit position (1-64, big-endian MSB first) // pos is 1-based DES bit position (1-64, big-endian MSB first)
let des_bit_1based = u64::from(pos); let des_bit_1based = u64::from(pos);
let des_bit_0based = des_bit_1based.saturating_sub(1); let des_bit_0based = des_bit_1based.saturating_sub(1); // 0-63
// Map DES big-endian position to u64 little-endian position // Map DES big-endian position to u64 little-endian position
// DES bit 1 (MSB) = u64 bit 63, DES bit 64 (LSB) = u64 bit 0
let bit_pos = 63u64.saturating_sub(des_bit_0based); let bit_pos = 63u64.saturating_sub(des_bit_0based);
// Extract bit from u64 at the correct position // Extract bit from u64 at the correct position
@ -119,8 +118,16 @@ pub fn pc2(key: u64) -> u64 {
.iter() .iter()
.enumerate() .enumerate()
.fold(0, |mut acc, (idx, &pos)| { .fold(0, |mut acc, (idx, &pos)| {
let bit_pos = u64::from(pos).saturating_sub(1); // pos is 1-based DES position in the 56-bit input (1-56)
let bit = ((key_56 >> bit_pos) & 1) << (47 - idx); let des_bit_1based = u64::from(pos);
let des_bit_0based = des_bit_1based.saturating_sub(1); // 0-55
// Map DES big-endian position to u64 little-endian position within 56 bits
let bit_pos = 55u64.saturating_sub(des_bit_0based);
// Extract bit from the 56-bit combined value
let bit = ((key_56 >> bit_pos) & 1) << (47usize.saturating_sub(idx));
acc |= bit; acc |= bit;
acc acc
}) })
@ -160,6 +167,12 @@ const fn shift(key: u32, shift: u8) -> u32 {
(main_shifted | wrapped_bits) & MASK (main_shifted | wrapped_bits) & MASK
} }
/// Concatinates two 28-bit numbers into 56-bit number
#[must_use]
fn contatinate_keys(left: u32, right: u32) -> u64 {
(u64::from(right) << 28) | u64::from(left)
}
/// Encrypts data using ECB mode. /// Encrypts data using ECB mode.
/// ///
/// # Arguments /// # Arguments
@ -312,8 +325,8 @@ mod tests {
#[test] #[test]
fn pc2_permutaion_correct() { fn pc2_permutaion_correct() {
let combined = 0x04FE12506091CEu64; // [D₁ << 28] | C₁ let combined = 0x00F0_CCAA_F556_678F; // [D_0 << 28] | C_0
let expected_subkey = 0xF3FDFBF373848CF5u64; // Expected 48-bit result let expected_subkey = 0x0000_CB3D_8B0E_17F5; // Expected 48-bit result
let result = pc2(combined); let result = pc2(combined);