30 lines
780 B
Rust
30 lines
780 B
Rust
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/// XOR cipher state for RsLi format
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pub struct XorState {
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lo: u8,
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hi: u8,
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}
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impl XorState {
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/// Create new XOR state from 16-bit key
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pub fn new(key16: u16) -> Self {
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Self {
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lo: (key16 & 0xFF) as u8,
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hi: ((key16 >> 8) & 0xFF) as u8,
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}
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}
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/// Decrypt a single byte and update state
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pub fn decrypt_byte(&mut self, encrypted: u8) -> u8 {
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self.lo = self.hi ^ self.lo.wrapping_shl(1);
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let decrypted = encrypted ^ self.lo;
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self.hi = self.lo ^ (self.hi >> 1);
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decrypted
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}
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}
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/// Decrypt entire buffer with XOR stream cipher
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pub fn xor_stream(data: &[u8], key16: u16) -> Vec<u8> {
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let mut state = XorState::new(key16);
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data.iter().map(|&b| state.decrypt_byte(b)).collect()
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}
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