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use std::{u8, u32};
use std::io;
use std::cmp::min;
use std::io::{Read,Write, ErrorKind};
use sodiumoxide::crypto::secretbox;
use sodiumoxide::crypto::secretbox::{Key, Nonce};
use rustc_serialize::base64::{ToBase64, FromBase64, STANDARD};
use std::mem::transmute;
// TODO: handle case of splitting up writes > 2^32 bytes into multiple small writes
pub struct SecretStream<S: Read+Write> {
pub read_nonce: Nonce,
pub write_nonce: Nonce,
pub key: Key,
inner: S,
read_buf: [u8; 4096+1024],
read_buf_offset: usize,
read_buf_len: usize,
}
impl<S: Read+Write> SecretStream<S> {
pub fn new(stream: S) -> SecretStream<S> {
SecretStream {
inner: stream,
read_nonce: secretbox::gen_nonce(),
write_nonce: secretbox::gen_nonce(),
key: secretbox::gen_key(),
read_buf: [0; 4096+1024],
read_buf_offset: 0,
read_buf_len: 0,
}
}
}
impl<S: Read+Write> Read for SecretStream<S> {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
// First try to return any extra older decrypted data
if self.read_buf_len > 0 {
let rlen = min(self.read_buf_len, buf.len());
buf[..rlen].clone_from_slice(
&self.read_buf[self.read_buf_offset..(self.read_buf_offset+rlen)]);
self.read_buf_offset += rlen;
self.read_buf_len -= rlen;
return Ok(rlen);
}
let mut header_buf = [0; 4];
try!(self.inner.read_exact(&mut header_buf));
let len: u32 = unsafe { transmute(header_buf) };
let len = u32::from_be(len);
let len = len as usize;
if len as usize > self.read_buf.len() {
return Err(io::Error::new(ErrorKind::Other,
format!("Message too big ({})", len)));
}
try!(self.inner.read_exact(&mut self.read_buf[..len]));
/*
println!("DECRYPT:");
println!("\tlen: {}", len);
println!("\tmsg: {:?}", &self.read_buf[..len]);
println!("\tnonce: {}", nonce2string(&self.write_nonce));
println!("\tkey: {}", key2string(&self.key));
*/
let cleartext = match secretbox::open(&self.read_buf[..len], &self.read_nonce, &self.key) {
Ok(cleartext) => cleartext,
Err(_) => { return Err(io::Error::new(ErrorKind::InvalidData,
"Failed to decrypt message (could mean corruption or malicious attack"))},
};
self.read_nonce.increment_le_inplace();
let clen = cleartext.len() as usize;
// Do we have more data than we can return this type? If so buffer it
if clen > buf.len() {
let buf_len = buf.len();
buf.clone_from_slice(&cleartext[..buf_len]);
self.read_buf[..(clen-buf_len)].clone_from_slice(&cleartext[buf_len..]);
self.read_buf_offset = 0;
self.read_buf_len = clen - buf_len;
return Ok(buf_len);
} else {
buf[..clen].clone_from_slice(&cleartext[..clen]);
return Ok(clen as usize);
}
}
}
impl<S: Read+Write> Write for SecretStream<S> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
assert!(buf.len() < u32::MAX as usize);
let raw_len = buf.len() as u32;
let ciphertext = secretbox::seal(buf, &self.write_nonce, &self.key);
let len = ciphertext.len() as u32;
let header_buf: [u8; 4] = unsafe { transmute(len.to_be()) };
try!(self.inner.write_all(&header_buf));
/*
println!("DECRYPT:");
println!("\tlen: {}", len);
println!("\tmsg: {:?}", ciphertext);
println!("\tnonce: {}", nonce2string(&self.write_nonce));
println!("\tkey: {}", key2string(&self.key));
let check = secretbox::open(&ciphertext, &self.write_nonce, &self.key).unwrap();
*/
self.write_nonce.increment_le_inplace();
try!(self.inner.write_all(&ciphertext[..]));
return Ok(raw_len as usize);
}
fn flush(&mut self) -> io::Result<()> {
return self.inner.flush();
}
}
pub fn key2string(key: &Key) -> String {
return (&(key[..])).to_base64(STANDARD);
}
pub fn string2key(s: &str) -> Result<Key, String> {
return Ok(Key::from_slice(&s.as_bytes().from_base64().unwrap()).unwrap());
}
pub fn nonce2string(nonce: &Nonce) -> String {
return (&(nonce[..])).to_base64(STANDARD);
}
pub fn string2nonce(s: &str) -> Result<Nonce, String> {
return Ok(Nonce::from_slice(&s.as_bytes().from_base64().unwrap()).unwrap());
}
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