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[kgm/ncm/kwm] refactor: improve performance for large file

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鲁树人
2024-09-15 23:25:19 +01:00
parent fd73e8b9a3
commit da806d7ad4
4 changed files with 18 additions and 30 deletions
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27
um_crypto/kgm/src/v3.rs
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@@ -25,34 +25,27 @@ impl DecipherV3 {
Ok(Self { slot_key, file_key })
}
fn offset_key(offset: usize) -> u8 {
let offset_key = (offset as u32).to_ne_bytes();
offset_key[0] ^ offset_key[1] ^ offset_key[2] ^ offset_key[3]
}
}
impl Decipher for DecipherV3 {
fn decrypt(&self, buffer: &mut [u8], offset: usize) {
let slot_key_stream = self
.slot_key
.iter()
.cycle()
.skip(offset % self.slot_key.len());
let file_key_stream = self
.file_key
.iter()
.cycle()
.skip(offset % self.file_key.len());
for (datum, offset) in buffer.iter_mut().zip(offset..) {
let offset_key = Self::offset_key(offset);
let mut offset = offset as u32;
let key_stream = slot_key_stream.zip(file_key_stream);
for (datum, (&slot_key, &file_key)) in buffer.iter_mut().zip(key_stream) {
let offset_key = offset.to_ne_bytes().iter().fold(0, |acc, &x| acc ^ x);
let file_key = self.file_key[offset % self.file_key.len()];
let slot_key = self.slot_key[offset % self.slot_key.len()];
let mut temp = *datum;
temp ^= file_key;
temp ^= temp.wrapping_shl(4);
temp ^= temp << 4;
temp ^= slot_key;
temp ^= offset_key;
*datum = temp;
offset = offset.wrapping_add(1);
}
}
}