lib_um_crypto_rust/um_cli/src/cmd/mg3d.rs

71 lines
2.1 KiB
Rust

use crate::Cli;
use anyhow::{bail, Result};
use clap::Args;
use std::fs::File;
use std::io::{BufReader, BufWriter, Read, Seek, SeekFrom, Write};
use std::path::PathBuf;
use umc_mg3d::{guess_key, Decipher};
/// Decrypt a mg3d file (Migu 3D Audio)
#[derive(Args)]
pub struct ArgsMigu3D {
/// Path to output file, e.g. /export/Music/song.wav
#[clap(short, long)]
output: PathBuf,
/// Path to input file, e.g. /export/Music/song.mg3d
#[arg(name = "input")]
input: PathBuf,
/// File key (androidFileKey/iosFileKey). Leave empty to guess the key.
#[clap(short = 'k', long = "file-key")]
file_key: Option<String>,
}
impl ArgsMigu3D {
pub fn run(&self, cli: &Cli) -> Result<i32> {
let mut reader = BufReader::with_capacity(cli.buffer_size, File::open(&self.input)?);
let mut writer = BufWriter::with_capacity(cli.buffer_size, File::create(&self.output)?);
let decipher = self.make_decipher(&mut reader)?;
if cli.verbose {
println!("final key: {}", hex::encode(decipher.get_key()));
}
let mut offset = 0usize;
let mut buffer = vec![0u8; cli.buffer_size];
loop {
let n = reader.read(&mut buffer[..])?;
if n == 0 {
break;
}
decipher.decrypt(&mut buffer[..n], offset);
writer.write_all(&buffer[..n])?;
offset += n;
}
Ok(0)
}
fn make_decipher<T>(&self, reader: &mut T) -> Result<Decipher>
where
T: Read + Seek + ?Sized,
{
let decipher = match &self.file_key {
None => {
let mut buffer = [0u8; 0x100];
reader.read_exact(&mut buffer)?;
reader.seek(SeekFrom::Current(-0x100))?;
let key = match guess_key(&buffer) {
Some(key) => key,
None => bail!("failed to guess a valid key"),
};
Decipher::new_from_final_key(&key)?
}
Some(key) => Decipher::new_from_file_key(key)?,
};
Ok(decipher)
}
}