commit 1352ef8ec8e60169925fc4dd356df0f48a5b9aed
Author: sky <3324298144@qq.com>
Date:   Fri Sep 6 01:19:05 2024 +0800

    init

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ea8c4bf
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/target
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..115668e
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,23 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "anyhow"
+version = "1.0.86"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b3d1d046238990b9cf5bcde22a3fb3584ee5cf65fb2765f454ed428c7a0063da"
+
+[[package]]
+name = "base64"
+version = "0.22.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72b3254f16251a8381aa12e40e3c4d2f0199f8c6508fbecb9d91f575e0fbb8c6"
+
+[[package]]
+name = "reuqm"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+ "base64",
+]
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..5740236
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "reuqm"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+anyhow = "1.0.86"
+base64 = "0.22.1"
diff --git a/src/decrypto/cipher.rs b/src/decrypto/cipher.rs
new file mode 100644
index 0000000..1462b1d
--- /dev/null
+++ b/src/decrypto/cipher.rs
@@ -0,0 +1,93 @@
+use std::cmp::min;
+
+use crate::{decrypto::rc4, key::read_key};
+use anyhow::{Error, Result};
+
+const FIRST_SEGMENT_SIZE: usize = 128;
+const OTHER_SEGMENT_SIZE: usize = 5120;
+
+pub struct Cipher {
+    hash: f64,
+    key: Vec<u8>,
+    key_stream: Vec<u8>,
+}
+
+impl Cipher {
+    pub fn new(raw_key: &str) -> Result<Self, Error> {
+        let key = read_key(raw_key)?;
+        let key_stream = rc4::new(&key);
+        let hash = hash(&key);
+        Ok(Self {
+            hash,
+            key,
+            key_stream,
+        })
+    }
+    pub fn decrypt(&mut self, mut offset: usize, mut buffer: &mut [u8]) {
+        if offset < FIRST_SEGMENT_SIZE {
+            let n = min(FIRST_SEGMENT_SIZE - offset, buffer.len());
+            let (block, rest) = buffer.split_at_mut(n);
+            buffer = rest;
+            self.decrypt_first_block(offset, block);
+            offset += n;
+        }
+
+        match offset % OTHER_SEGMENT_SIZE {
+            0 => {}
+            excess => {
+                let n = min(OTHER_SEGMENT_SIZE - excess, buffer.len());
+                let (block, rest) = buffer.split_at_mut(n);
+                buffer = rest;
+                self.decrypt_other_block(offset, block);
+                offset += n;
+            }
+        };
+
+        while !buffer.is_empty() {
+            let n: usize = min(OTHER_SEGMENT_SIZE, buffer.len());
+            let (block, rest) = buffer.split_at_mut(n);
+            buffer = rest;
+            self.decrypt_other_block(offset, block);
+            offset += n;
+        }
+    }
+    fn decrypt_first_block(&mut self, offset: usize, dst: &mut [u8]) {
+        let n = self.key.len();
+
+        for (value, offset) in dst.iter_mut().zip(offset..) {
+            *value ^= self.key[idx(offset as u64, self.key[offset % n], self.hash) as usize % n];
+        }
+    }
+    fn decrypt_other_block(&mut self, offset: usize, dst: &mut [u8]) {
+        let n = self.key.len();
+        let id = offset / OTHER_SEGMENT_SIZE;
+        let block_offset = offset % OTHER_SEGMENT_SIZE;
+        let seed = self.key[id % n];
+        let skip = idx(id as u64, seed, self.hash) % 512;
+        let key_stream = self.key_stream.iter().skip(skip as usize + block_offset);
+        for (datum, &key) in dst.iter_mut().zip(key_stream) {
+            *datum ^= key;
+        }
+    }
+}
+
+fn hash(key: &Vec<u8>) -> f64 {
+    let mut hash = 1u32;
+    for v in key.iter() {
+        if *v == 0 {
+            continue;
+        }
+        let next_hash = hash.wrapping_mul(*v as u32);
+        if next_hash == 0 || next_hash <= hash {
+            break;
+        }
+        hash = next_hash;
+    }
+    hash.into()
+}
+fn idx(id: u64, seed: u8, hash: f64) -> u32 {
+    match seed {
+        0 => 0,
+        seed => (hash / ((id + 1).wrapping_mul(seed.into()) as f64) * 100.0) as u32,
+    }
+}
diff --git a/src/decrypto/mod.rs b/src/decrypto/mod.rs
new file mode 100644
index 0000000..fbb2cb5
--- /dev/null
+++ b/src/decrypto/mod.rs
@@ -0,0 +1,2 @@
+pub mod cipher;
+mod rc4;
diff --git a/src/decrypto/rc4.rs b/src/decrypto/rc4.rs
new file mode 100644
index 0000000..5b7ffdf
--- /dev/null
+++ b/src/decrypto/rc4.rs
@@ -0,0 +1,62 @@
+pub fn new(key: &Vec<u8>) -> Vec<u8> {
+    let key_lenght = key.len();
+    // init
+    let mut s_box = Vec::new();
+    let mut t_box = Vec::new();
+    for i in 0..key_lenght {
+        s_box.push(i as u8);
+        t_box.push(key[i % key_lenght]);
+    }
+
+    // init S box
+    let mut j = 0;
+    for i in 0..key_lenght {
+        j = (j + s_box[i] as usize + t_box[i] as usize) % 512;
+        s_box.swap(i, j);
+    }
+
+    let mut i = 0;
+    let mut j = 0;
+    let mut ks = Vec::new();
+    for _ in 0..(5120 + 512) {
+        i = (i + 1) % key_lenght;
+        j = (j + s_box[i] as usize) % key_lenght;
+        s_box.swap(i, j);
+        let t = (s_box[i] as usize + s_box[j] as usize) % key_lenght;
+        ks.push(0 ^ s_box[t]);
+    }
+    ks
+}
+
+#[test]
+fn test() {
+    let k = vec![
+        102, 121, 54, 88, 65, 52, 108, 55, 49, 87, 86, 79, 104, 83, 52, 106, 107, 50, 113, 54, 83,
+        82, 100, 99, 56, 103, 112, 78, 51, 56, 52, 112, 77, 53, 57, 56, 119, 49, 99, 117, 51, 76,
+        120, 121, 49, 109, 83, 73, 49, 74, 56, 52, 55, 110, 99, 98, 77, 114, 112, 90, 72, 65, 82,
+        48, 53, 50, 68, 48, 49, 108, 114, 97, 67, 82, 73, 83, 103, 116, 101, 53, 120, 121, 81, 73,
+        89, 76, 53, 88, 100, 53, 53, 100, 116, 111, 97, 83, 119, 51, 104, 109, 48, 55, 75, 102,
+        110, 66, 110, 76, 53, 49, 97, 102, 112, 76, 115, 104, 56, 113, 57, 89, 74, 81, 57, 103, 99,
+        55, 77, 99, 51, 68, 50, 72, 48, 51, 86, 114, 121, 100, 75, 87, 66, 48, 54, 116, 107, 118,
+        105, 76, 67, 65, 51, 68, 68, 51, 56, 103, 49, 52, 89, 87, 54, 76, 52, 81, 104, 66, 79, 52,
+        112, 75, 49, 73, 114, 98, 68, 67, 84, 50, 50, 87, 74, 76, 104, 57, 102, 52, 119, 109, 116,
+        51, 75, 71, 56, 65, 86, 80, 52, 53, 100, 71, 101, 69, 113, 81, 49, 75, 77, 54, 120, 102,
+        85, 89, 121, 65, 101, 79, 101, 76, 74, 104, 99, 49, 75, 102, 55, 98, 55, 48, 71, 110, 98,
+        48, 120, 57, 78, 120, 68, 73, 49, 52, 55, 103, 99, 89, 112, 97, 57, 88, 72, 51, 48, 75, 70,
+        72, 106, 122, 72, 98, 100, 48, 113, 77, 56, 50, 108, 50, 65, 113, 69, 88, 102, 99, 70, 49,
+        103, 54, 50, 103, 98, 90, 50, 112, 75, 116, 57, 103, 80, 97, 55, 54, 118, 57, 101, 57, 57,
+        88, 57, 48, 49, 54, 115, 56, 52, 53, 79, 87, 66, 102, 116, 111, 54, 89, 51, 122, 102, 53,
+        116, 50, 101, 56, 101, 102, 83, 111, 74, 81, 110, 50, 85, 56, 55, 51, 84, 81, 54, 51, 86,
+        82, 51, 50, 72, 120, 56, 54, 115, 56, 117, 87, 122, 79, 56, 56, 105, 83, 53, 54, 82, 82,
+        50, 103, 81, 119, 99, 56, 103, 54, 97, 83, 54, 107, 52, 102, 105, 68, 54, 108, 99, 66, 99,
+        70, 122, 97, 101, 109, 72, 53, 105, 88, 55, 55, 111, 73, 50, 88, 114, 103, 82, 50, 99, 99,
+        48, 57, 113, 106, 100, 72, 107, 109, 100, 54, 84, 51, 79, 106, 86, 97, 102, 118, 105, 76,
+        56, 104, 107, 56, 53, 79, 67, 75, 50, 103, 53, 56, 112, 111, 117, 108, 54, 98, 110, 119,
+        118, 118, 49, 80, 69, 119, 102, 101, 56, 51, 116, 71, 48, 86, 106, 104, 103, 71, 77, 72,
+        52, 54, 117, 88, 67, 54, 86, 55, 48, 102, 67, 51, 49, 74, 57, 52, 119, 56, 54, 111, 119,
+        108, 48, 79, 55, 72, 73, 57, 49, 72, 51, 81, 70, 74, 99, 55, 78, 53, 82, 84, 103, 52, 50,
+        115, 112, 54, 54, 50, 52, 65, 114, 122,
+    ];
+    let rs4 = new(&k);
+    println!("{:?}", rs4);
+}
diff --git a/src/key/mod.rs b/src/key/mod.rs
new file mode 100644
index 0000000..9d84894
--- /dev/null
+++ b/src/key/mod.rs
@@ -0,0 +1,91 @@
+mod tea;
+use anyhow::{Error, Result};
+use base64::prelude::{Engine, BASE64_STANDARD as base64};
+
+pub fn read_key(raw_key: &str) -> Result<Vec<u8>> {
+    let base64_key = match base64.decode(raw_key) {
+        Ok(k) => k,
+        Err(err) => {
+            return Err(Error::msg(format!(
+                "use base64 decode raw key Failed,{err}"
+            )))
+        }
+    };
+
+    let simple_key: [u8; 8] = [105, 86, 70, 56, 43, 32, 21, 11];
+    let mut tea_key = vec![0; 16];
+    for i in 0..8 {
+        tea_key[i << 1] = simple_key[i];
+        tea_key[(i << 1) + 1] = base64_key[i];
+    }
+    let mut rs = decrypt_tencent_tea(base64_key[8..].to_owned(), tea_key)?;
+    let mut dkv1 = base64_key[..8].to_owned();
+    dkv1.append(&mut rs);
+    Ok(dkv1.into())
+}
+
+fn decrypt_tencent_tea(in_buf: Vec<u8>, key: Vec<u8>) -> Result<Vec<u8>, Error> {
+    const SALTLEN: usize = 2;
+    const ZEROEN: usize = 7;
+    if in_buf.len() % 8 != 0 {
+        return Err(Error::msg("inBuf size not a multiple of the block size"));
+    }
+    if in_buf.len() < 16 {
+        return Err(Error::msg("inBuf size too small"));
+    }
+    let key = key[0..16].try_into().unwrap();
+    let blk = tea::Tea::new(key, 32);
+    let mut dst = blk.decrypt(in_buf[0..8].to_owned());
+
+    let pad_len = &dst[0] & 0x7;
+    let out_len = in_buf.len() - 1 - pad_len as usize - SALTLEN - ZEROEN;
+    let mut out = vec![0; out_len];
+    let mut iv_prev = vec![0; 8];
+    let mut iv_cur = in_buf[0..8].to_owned();
+    let mut in_buf_pos = 8;
+    let mut dst_idx = 1 + pad_len;
+    let mut i = 1;
+    while i <= SALTLEN {
+        if dst_idx < 8 {
+            dst_idx += 1;
+            i += 1;
+        } else if dst_idx == 8 {
+            iv_prev = iv_cur.clone()[0..8].to_owned();
+            iv_cur = in_buf[in_buf_pos..(in_buf_pos + 8)].to_owned();
+            dst = xor_8bytes(dst.clone(), in_buf[in_buf_pos..(in_buf_pos + 8)].to_owned());
+            dst = blk.decrypt(dst.clone());
+            in_buf_pos += 8;
+            dst_idx = 0;
+        }
+    }
+    let mut out_pos = 0;
+    while out_pos < out_len {
+        if dst_idx < 8 {
+            out[out_pos] = dst[dst_idx as usize] ^ iv_prev[dst_idx as usize];
+            dst_idx += 1;
+            out_pos += 1;
+            continue;
+        }
+        iv_prev = iv_cur.clone()[0..8].to_owned();
+        iv_cur = in_buf[in_buf_pos..(in_buf_pos + 8)].to_owned();
+        dst = xor_8bytes(dst.clone(), in_buf[in_buf_pos..(in_buf_pos + 8)].to_owned());
+        dst = blk.decrypt(dst.clone());
+        in_buf_pos += 8;
+        dst_idx = 0;
+    }
+    let mut i = 1;
+    while i <= ZEROEN {
+        i += 1;
+        if dst[dst_idx as usize] != iv_prev[dst_idx as usize] {
+            return Err(Error::msg("zero check failed"));
+        }
+    }
+    Ok(out)
+}
+pub fn xor_8bytes(a: Vec<u8>, b: Vec<u8>) -> Vec<u8> {
+    let mut dst = vec![0; 8];
+    for i in 0..8 {
+        dst[i] = a[i] ^ b[i];
+    }
+    dst
+}
diff --git a/src/key/tea.rs b/src/key/tea.rs
new file mode 100644
index 0000000..cd4c66c
--- /dev/null
+++ b/src/key/tea.rs
@@ -0,0 +1,51 @@
+pub struct Tea {
+    key: [u32; 4],
+    rounds: u32,
+}
+
+impl Tea {
+    pub fn new(key: [u8; 16], rounds: u32) -> Self {
+        let key = [
+            u32::from_be_bytes(key[0..4].try_into().unwrap()),
+            u32::from_be_bytes(key[4..8].try_into().unwrap()),
+            u32::from_be_bytes(key[8..12].try_into().unwrap()),
+            u32::from_be_bytes(key[12..16].try_into().unwrap()),
+        ];
+        Self { key, rounds }
+    }
+    pub fn decrypt(&self, bl: Vec<u8>) -> Vec<u8> {
+        let delta = 0x9E3779b9;
+        let decrypto = |v: [u32; 2], k: [u32; 4]| -> (u32, u32) {
+            let mut sum: u32 = (self.rounds / 2).wrapping_mul(delta);
+            let mut v0 = v[0];
+            let mut v1 = v[1];
+            for _ in 0..(self.rounds / 2) {
+                v1 = v1.wrapping_sub(
+                    ((v0 << 4).wrapping_add(k[2]))
+                        ^ (v0.wrapping_add(sum))
+                        ^ ((v0 >> 5).wrapping_add(k[3])),
+                );
+                v0 = v0.wrapping_sub(
+                    ((v1 << 4).wrapping_add(k[0]))
+                        ^ (v1.wrapping_add(sum))
+                        ^ ((v1 >> 5).wrapping_add(k[1])),
+                );
+                sum = sum.wrapping_sub(delta);
+            }
+            (v0, v1)
+        };
+        let v0 = u32::from_be_bytes(bl[0..4].try_into().unwrap());
+        let v1 = u32::from_be_bytes(bl[4..8].try_into().unwrap());
+        let (v0, v1) = decrypto([v0, v1], self.key);
+        [v0.to_be_bytes(), v1.to_be_bytes()].concat()
+    }
+}
+
+#[test]
+fn test() {
+    let v: [u8; 16] = [
+        33, 14, 26, 47, 81, 10, 19, 22, 47, 35, 88, 21, 45, 23, 44, 55,
+    ];
+    let k1 = u32::from_be_bytes(v[0..4].try_into().unwrap());
+    assert_eq!(k1, 554572335);
+}
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..616641c
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,10 @@
+pub mod decrypto;
+mod key;
+use anyhow::{Error, Result};
+
+pub fn decrypt(filename: &str, raw_key: &str) -> Result<Vec<u8>, Error> {
+    let mut audio = std::fs::read(filename)?;
+    let mut cipher = decrypto::cipher::Cipher::new(raw_key)?;
+    cipher.decrypt(0, &mut audio);
+    Ok(audio)
+}