From 7bcdc3b4ca460aec2b98fb2dca6165788c562b05 Mon Sep 17 00:00:00 2001
From: Igor Tolmachev <me@igorek.dev>
Date: Sat, 20 Jul 2024 16:52:39 +0900
Subject: Partial aes implementation and others improvements

---
 src/zip/encryption/aes.rs  |  46 ++++++++++++++++++++
 src/zip/encryption/mod.rs  |   5 +++
 src/zip/encryption/weak.rs | 105 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 156 insertions(+)
 create mode 100644 src/zip/encryption/aes.rs
 create mode 100644 src/zip/encryption/mod.rs
 create mode 100644 src/zip/encryption/weak.rs

(limited to 'src/zip/encryption')

diff --git a/src/zip/encryption/aes.rs b/src/zip/encryption/aes.rs
new file mode 100644
index 0000000..6f41aaa
--- /dev/null
+++ b/src/zip/encryption/aes.rs
@@ -0,0 +1,46 @@
+use crate::utils::ReadUtils;
+use aes::cipher::generic_array::GenericArray;
+use aes::cipher::BlockEncrypt;
+use std::io::{Read, Result as IoResult};
+
+#[allow(dead_code)]
+pub struct AesDecoder<Io: Read, Aes: BlockEncrypt> {
+    io: Io,
+    aes: Aes,
+
+    counter: u128,
+    block: [u8; 16],
+    cursor: usize,
+}
+
+impl<Io: Read, Aes: BlockEncrypt> AesDecoder<Io, Aes> {
+    pub fn new(mut io: Io, aes: Aes) -> IoResult<Self> {
+        let block = io.read_arr::<16>()?;
+        let mut decoder = Self {
+            io,
+            aes,
+            counter: 1,
+            block,
+            cursor: 0,
+        };
+        decoder.decrypt_block();
+        Ok(decoder)
+    }
+
+    #[inline]
+    fn decrypt_block(&mut self) {
+        let mut mask = self.counter.to_le_bytes();
+        self.aes
+            .encrypt_block(GenericArray::from_mut_slice(&mut mask));
+        for (b, m) in self.block.iter_mut().zip(mask) {
+            *b ^= m
+        }
+        self.counter += 1;
+    }
+}
+
+impl<Io: Read, Aes: BlockEncrypt> Read for AesDecoder<Io, Aes> {
+    fn read(&mut self, buf: &mut [u8]) -> IoResult<usize> {
+        todo!()
+    }
+}
diff --git a/src/zip/encryption/mod.rs b/src/zip/encryption/mod.rs
new file mode 100644
index 0000000..8cacaf9
--- /dev/null
+++ b/src/zip/encryption/mod.rs
@@ -0,0 +1,5 @@
+mod aes;
+mod weak;
+
+pub use aes::AesDecoder;
+pub use weak::{Keys, WeakDecoder};
diff --git a/src/zip/encryption/weak.rs b/src/zip/encryption/weak.rs
new file mode 100644
index 0000000..144cd53
--- /dev/null
+++ b/src/zip/encryption/weak.rs
@@ -0,0 +1,105 @@
+use std::io::{Read, Result as IoResult};
+
+const TABLE: [u32; 256] = generate_table();
+
+const fn generate_table() -> [u32; 256] {
+    let mut table = [0; 256];
+
+    let mut i = 0;
+    while i <= 255 {
+        let mut t = i as u32;
+
+        let mut j = 0;
+        while j < 8 {
+            if (t & 1) > 0 {
+                t = (t >> 1) ^ 0xEDB88320
+            } else {
+                t >>= 1
+            }
+            j += 1;
+        }
+
+        table[i] = t;
+        i += 1
+    }
+
+    table
+}
+
+fn crc32(byte: u8, crc: u32) -> u32 {
+    (crc >> 8) ^ TABLE[((crc & 0xFF) as u8 ^ byte) as usize]
+}
+
+pub struct Keys {
+    key0: u32,
+    key1: u32,
+    key2: u32,
+}
+
+impl Keys {
+    pub fn new() -> Self {
+        Self {
+            key0: 305419896,
+            key1: 591751049,
+            key2: 878082192,
+        }
+    }
+
+    fn update(&mut self, byte: u8) {
+        self.key0 = crc32(byte, self.key0);
+        self.key1 = self
+            .key1
+            .wrapping_add(self.key0 & 0xFF)
+            .wrapping_mul(134775813)
+            .wrapping_add(1);
+        self.key2 = crc32((self.key1 >> 24) as u8, self.key2);
+    }
+
+    pub fn set_password(&mut self, passwd: &[u8]) {
+        for b in passwd {
+            self.update(*b)
+        }
+    }
+
+    pub fn set_header(&mut self, header: [u8; 12]) -> u8 {
+        for b in &header[..11] {
+            self.decode_byte(*b);
+        }
+        self.decode_byte(header[11])
+    }
+
+    #[allow(dead_code)]
+    pub fn encode_bytes(&mut self, byte: u8) -> u8 {
+        let key = self.key2 | 2;
+        self.update(byte);
+        byte ^ ((key.wrapping_mul(key ^ 1)) >> 8) as u8
+    }
+
+    pub fn decode_byte(&mut self, byte: u8) -> u8 {
+        let key = self.key2 | 2;
+        let byte = byte ^ ((key.wrapping_mul(key ^ 1)) >> 8) as u8;
+        self.update(byte);
+        byte
+    }
+}
+
+pub struct WeakDecoder<Io: Read> {
+    io: Io,
+    keys: Keys,
+}
+
+impl<Io: Read> WeakDecoder<Io> {
+    pub fn new(io: Io, keys: Keys) -> Self {
+        WeakDecoder { io, keys }
+    }
+}
+
+impl<Io: Read> Read for WeakDecoder<Io> {
+    fn read(&mut self, buf: &mut [u8]) -> IoResult<usize> {
+        let bytes = self.io.read(buf)?;
+        for i in 0..bytes {
+            buf[i] = self.keys.decode_byte(buf[i]);
+        }
+        Ok(bytes)
+    }
+}
-- 
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