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Complete rewrite of crypto part

This commit is contained in:
Dennis Schwerdel 2015-11-24 23:47:38 +01:00
parent be3a85c3b9
commit 83fb941599
6 changed files with 146 additions and 112 deletions
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4
Cargo.toml
View File

@ -10,11 +10,11 @@ docopt = "0.6"
rustc-serialize = "0.3"
log = "0.3"
epoll = "0.2"
sodiumoxide = {version = "0.0.9", optional = true}
libsodium-sys = {version = "0.0.9", optional = true}
[build-dependencies]
gcc = "0.3"
[features]
default = []
crypto = ["sodiumoxide"] #not default as it requires external library
crypto = ["libsodium-sys"] #not default as it requires external library

6
src/crypto/dummy.rs
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@ -13,7 +13,7 @@ impl Crypto {
0
}
pub fn auth_bytes(&self) -> usize {
pub fn additional_bytes(&self) -> usize {
0
}
@ -21,11 +21,11 @@ impl Crypto {
panic!("This binary has no crypto support");
}
pub fn decrypt(&self, mut _buf: &mut [u8], _nonce: &[u8], _hash: &[u8]) -> Result<(), Error> {
pub fn decrypt(&self, mut _buf: &mut [u8], _nonce: &[u8], _hash: &[u8]) -> Result<usize, Error> {
unreachable!("This should never be called")
}
pub fn encrypt(&mut self, mut _buf: &mut [u8]) -> (Vec<u8>, Vec<u8>) {
pub fn encrypt(&mut self, mut _buf: &mut [u8], _mlen: usize, _nonce_bytes: &mut [u8], _header: &[u8]) -> usize {
unreachable!("This should never be called")
}
}

138
src/crypto/sodium.rs
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@ -1,19 +1,15 @@
use std::mem;
use std::{mem, ptr};
use sodiumoxide::crypto::stream::chacha20::{Key as CryptoKey, Nonce, stream_xor_inplace, gen_nonce,
KEYBYTES, NONCEBYTES};
use sodiumoxide::crypto::auth::hmacsha512256::{Key as AuthKey, Tag, authenticate, verify, TAGBYTES};
use sodiumoxide::crypto::pwhash::{derive_key, SALTBYTES, Salt, HASHEDPASSWORDBYTES,
OPSLIMIT_INTERACTIVE, MEMLIMIT_INTERACTIVE};
use libsodium_sys::*;
use super::super::types::Error;
pub enum Crypto {
None,
ChaCha20HmacSha512256{crypto_key: CryptoKey, auth_key: AuthKey, nonce: Nonce}
ChaCha20Poly1305{key: [u8; 32], nonce: [u8; 8]}
}
fn inc_nonce(nonce: Nonce) -> Nonce {
fn inc_nonce(nonce: [u8; 8]) -> [u8; 8] {
unsafe {
let mut num: u64 = mem::transmute(nonce);
num = num.wrapping_add(1);
@ -25,64 +21,101 @@ impl Crypto {
pub fn method(&self) -> u8 {
match self {
&Crypto::None => 0,
&Crypto::ChaCha20HmacSha512256{crypto_key: _, auth_key: _, nonce: _} => 1
&Crypto::ChaCha20Poly1305{key: _, nonce: _} => 1
}
}
pub fn nonce_bytes(&self) -> usize {
match self {
&Crypto::None => 0,
&Crypto::ChaCha20HmacSha512256{crypto_key: _, auth_key: _, nonce: _} => NONCEBYTES
&Crypto::ChaCha20Poly1305{key: _, ref nonce} => nonce.len()
}
}
pub fn auth_bytes(&self) -> usize {
pub fn additional_bytes(&self) -> usize {
match self {
&Crypto::None => 0,
&Crypto::ChaCha20HmacSha512256{crypto_key: _, auth_key: _, nonce: _} => TAGBYTES
&Crypto::ChaCha20Poly1305{key: _, nonce: _} => crypto_aead_chacha20poly1305_ABYTES
}
}
pub fn from_shared_key(password: &str) -> Self {
let salt = "vpncloudVPNCLOUDvpncl0udVpnCloud";
assert_eq!(salt.len(), SALTBYTES);
let mut key = [0; HASHEDPASSWORDBYTES];
derive_key(&mut key, password.as_bytes(), &Salt::from_slice(salt.as_bytes()).unwrap(),
OPSLIMIT_INTERACTIVE, MEMLIMIT_INTERACTIVE).unwrap();
let mut crypto_key = CryptoKey([0; KEYBYTES]);
let mut auth_key = AuthKey([0; KEYBYTES]);
for i in 0..KEYBYTES {
crypto_key.0[i] = key[i];
let salt = "vpncloudVPNCLOUDvpncl0udVpnCloud".as_bytes();
assert_eq!(salt.len(), crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
let mut key = [0; crypto_pwhash_scryptsalsa208sha256_STRBYTES];
let res = unsafe { crypto_pwhash_scryptsalsa208sha256(
key.as_mut_ptr(),
key.len() as u64,
password.as_bytes().as_ptr(),
password.as_bytes().len() as u64,
salt.as_ptr() as *const [u8; crypto_pwhash_scryptsalsa208sha256_SALTBYTES],
crypto_pwhash_scryptsalsa208sha256_OPSLIMIT_INTERACTIVE as u64,
crypto_pwhash_scryptsalsa208sha256_MEMLIMIT_INTERACTIVE
) };
if res != 0 {
panic!("Key derivation failed");
}
for i in 0..KEYBYTES {
auth_key.0[i] = key[KEYBYTES+i];
let mut crypto_key = [0; 32];
for i in 0..crypto_key.len() {
crypto_key[i] = key[i];
}
Crypto::ChaCha20HmacSha512256{crypto_key: crypto_key, auth_key: auth_key, nonce: gen_nonce()}
let mut nonce = [0u8; 8];
unsafe { randombytes_buf(nonce.as_mut_ptr(), nonce.len()) };
Crypto::ChaCha20Poly1305{key: crypto_key, nonce: nonce}
}
pub fn decrypt(&self, mut buf: &mut [u8], nonce: &[u8], hash: &[u8]) -> Result<(), Error> {
pub fn decrypt(&self, mut buf: &mut [u8], nonce: &[u8], header: &[u8]) -> Result<usize, Error> {
match self {
&Crypto::None => unreachable!("This should never be called"),
&Crypto::ChaCha20HmacSha512256{ref crypto_key, ref auth_key, nonce: _} => {
let nonce = Nonce::from_slice(nonce).unwrap();
let hash = Tag::from_slice(hash).unwrap();
stream_xor_inplace(&mut buf, &nonce, crypto_key);
match verify(&hash, &buf, auth_key) {
true => Ok(()),
false => Err(Error::CryptoError("Decryption failed"))
&Crypto::None => Ok(buf.len()),
&Crypto::ChaCha20Poly1305{ref key, nonce: _} => {
let mut mlen: u64 = buf.len() as u64;
let res = unsafe { crypto_aead_chacha20poly1305_decrypt(
buf.as_mut_ptr(), // Base pointer to buffer
&mut mlen, // Mutable size of buffer (will be set to used size)
ptr::null_mut::<[u8; 0]>(), // Mutable base pointer to secret nonce (always NULL)
buf.as_ptr(), // Base pointer to message
buf.len() as u64, // Size of message
header.as_ptr(), // Base pointer to additional data
header.len() as u64, // Size of additional data
nonce.as_ptr() as *const [u8; 8], // Base pointer to public nonce
key.as_ptr() as *const [u8; 32] // Base pointer to key
) };
match res {
0 => Ok(mlen as usize),
_ => Err(Error::CryptoError("Failed to decrypt"))
}
}
}
}
pub fn encrypt(&mut self, mut buf: &mut [u8]) -> (Vec<u8>, Vec<u8>) {
pub fn encrypt(&mut self, mut buf: &mut [u8], mlen: usize, nonce_bytes: &mut [u8], header: &[u8]) -> usize {
match self {
&mut Crypto::None => unreachable!("This should never be called"),
&mut Crypto::ChaCha20HmacSha512256{ref crypto_key, ref auth_key, ref mut nonce} => {
&mut Crypto::None => mlen,
&mut Crypto::ChaCha20Poly1305{ref key, ref mut nonce} => {
*nonce = inc_nonce(*nonce);
let hash = authenticate(&buf, auth_key);
stream_xor_inplace(&mut buf, nonce, crypto_key);
(nonce.0.iter().map(|v| *v).collect(), hash.0.iter().map(|v| *v).collect())
let mut clen: u64 = buf.len() as u64;
assert_eq!(nonce_bytes.len(), nonce.len());
assert_eq!(nonce.len(), crypto_aead_chacha20poly1305_NPUBBYTES);
assert_eq!(key.len(), crypto_aead_chacha20poly1305_KEYBYTES);
assert_eq!(0, crypto_aead_chacha20poly1305_NSECBYTES);
assert!(clen as usize >= mlen + crypto_aead_chacha20poly1305_ABYTES);
let res = unsafe { crypto_aead_chacha20poly1305_encrypt(
buf.as_mut_ptr(), // Base pointer to buffer
&mut clen, // Mutable size of buffer (will be set to used size)
buf.as_ptr(), // Base pointer to message
mlen as u64, // Size of message
header.as_ptr(), // Base pointer to additional data
header.len() as u64, // Size of additional data
ptr::null::<[u8; 0]>(), // Base pointer to secret nonce (always NULL)
nonce.as_ptr() as *const [u8; 8], // Base pointer to public nonce
key.as_ptr() as *const [u8; 32] // Base pointer to key
) };
assert_eq!(res, 0);
assert_eq!(clen as usize, mlen + crypto_aead_chacha20poly1305_ABYTES);
unsafe {
ptr::copy_nonoverlapping(nonce.as_ptr(), nonce_bytes.as_mut_ptr(), nonce.len());
}
clen as usize
}
}
}
@ -93,14 +126,21 @@ fn encrypt_decrypt() {
let mut sender = Crypto::from_shared_key("test");
let receiver = Crypto::from_shared_key("test");
let msg = "HelloWorld0123456789";
let mut buffer: Vec<u8> = msg.bytes().collect();
let (nonce1, hash1) = sender.encrypt(&mut buffer);
assert!(msg.as_bytes() != &buffer as &[u8]);
receiver.decrypt(&mut buffer, &nonce1, &hash1).unwrap();
assert_eq!(msg.as_bytes(), &buffer as &[u8]);
let (nonce2, hash2) = sender.encrypt(&mut buffer);
assert!(nonce1 != nonce2);
assert!(hash1 == hash2);
receiver.decrypt(&mut buffer, &nonce2, &hash2).unwrap();
assert_eq!(msg.as_bytes(), &buffer as &[u8]);
let msg_bytes = msg.as_bytes();
let mut buffer = [0u8; 1024];
let header = [0u8; 8];
for i in 0..msg_bytes.len() {
buffer[i] = msg_bytes[i];
}
let mut nonce1 = [0u8; 8];
let size = sender.encrypt(&mut buffer, msg_bytes.len(), &mut nonce1, &header);
assert_eq!(size, msg_bytes.len() + sender.additional_bytes());
assert!(msg_bytes != &buffer[..msg_bytes.len()] as &[u8]);
receiver.decrypt(&mut buffer[..size], &nonce1, &header).unwrap();
assert_eq!(msg_bytes, &buffer[..msg_bytes.len()] as &[u8]);
let mut nonce2 = [0u8; 8];
let size = sender.encrypt(&mut buffer, msg_bytes.len(), &mut nonce2, &header);
assert!(nonce1 != nonce2);
receiver.decrypt(&mut buffer[..size], &nonce2, &header).unwrap();
assert_eq!(msg_bytes, &buffer[..msg_bytes.len()] as &[u8]);
}

5
src/main.rs
View File

@ -3,7 +3,7 @@ extern crate time;
extern crate docopt;
extern crate rustc_serialize;
extern crate epoll;
#[cfg(feature = "crypto")] extern crate sodiumoxide;
#[cfg(feature = "crypto")] extern crate libsodium_sys;
mod util;
mod types;
@ -31,9 +31,6 @@ use crypto::Crypto;
//TODO: Implement IPv6
//TODO: Call close
//FIXME: The crypto method should be signaled as part of the protocol
//FIXME: The HMAC should also include the header
//FIXME: Encryption should also include all following additional headers
struct SimpleLogger;

56
src/udpmessage.rs
View File

@ -65,7 +65,8 @@ impl<'a> fmt::Debug for Message<'a> {
}
pub fn decode<'a>(data: &'a mut [u8], crypto: &mut Crypto) -> Result<(Options, Message<'a>), Error> {
if data.len() < mem::size_of::<TopHeader>() {
let mut end = data.len();
if end < mem::size_of::<TopHeader>() {
return Err(Error::ParseError("Empty message"));
}
let mut pos = 0;
@ -81,18 +82,21 @@ pub fn decode<'a>(data: &'a mut [u8], crypto: &mut Crypto) -> Result<(Options, M
return Err(Error::CryptoError("Wrong crypto method"));
}
if crypto.method() > 0 {
let len = crypto.nonce_bytes() + crypto.auth_bytes();
if data.len() < pos + len {
let len = crypto.nonce_bytes();
if end < pos + len {
return Err(Error::ParseError("Truncated crypto header"));
}
let (crypto_header, crypto_data) = data[pos..].split_at_mut(len);
{
let (before, after) = data.split_at_mut(pos);
let (nonce, crypto_data) = after.split_at_mut(len);
pos += len;
let (nonce, hash) = crypto_header.split_at(crypto.nonce_bytes());
try!(crypto.decrypt(crypto_data, nonce, hash));
end = try!(crypto.decrypt(crypto_data, nonce, &before[..mem::size_of::<TopHeader>()])) + pos;
}
assert_eq!(end, data.len()-crypto.additional_bytes());
}
let mut options = Options::default();
if header.flags & 0x01 > 0 {
if data.len() < pos + NETWORK_ID_BYTES {
if end < pos + NETWORK_ID_BYTES {
return Err(Error::ParseError("Truncated options"));
}
let id = u64::from_be(*unsafe { as_obj::<u64>(&data[pos..pos+NETWORK_ID_BYTES]) });
@ -100,15 +104,15 @@ pub fn decode<'a>(data: &'a mut [u8], crypto: &mut Crypto) -> Result<(Options, M
pos += NETWORK_ID_BYTES;
}
let msg = match header.msgtype {
0 => Message::Data(&data[pos..]),
0 => Message::Data(&data[pos..end]),
1 => {
if data.len() < pos + 1 {
if end < pos + 1 {
return Err(Error::ParseError("Empty peers"));
}
let count = data[pos];
pos += 1;
let len = count as usize * 6;
if data.len() < pos + len {
if end < pos + len {
return Err(Error::ParseError("Peer data too short"));
}
let mut peers = Vec::with_capacity(count as usize);
@ -127,28 +131,24 @@ pub fn decode<'a>(data: &'a mut [u8], crypto: &mut Crypto) -> Result<(Options, M
Message::Peers(peers)
},
2 => {
if data.len() < pos + 1 {
if end < pos + 1 {
return Err(Error::ParseError("Init data too short"));
}
let count = data[pos] as usize;
pos += 1;
let mut addrs = Vec::with_capacity(count);
for _ in 0..count {
if data.len() < pos + 1 {
if end < pos + 1 {
return Err(Error::ParseError("Init data too short"));
}
let len = data[pos] as usize;
pos += 1;
if data.len() < pos + len {
if end < pos + len + 1 {
return Err(Error::ParseError("Init data too short"));
}
let base = Address(to_vec(&data[pos..pos+len]));
pos += len;
if data.len() < pos + 1 {
return Err(Error::ParseError("Init data too short"));
}
let prefix_len = data[pos];
pos += 1;
let prefix_len = data[pos+len];
pos += len + 1;
addrs.push(Range{base: base, prefix_len: prefix_len});
}
Message::Init(addrs)
@ -176,11 +176,7 @@ pub fn encode(options: &Options, msg: &Message, buf: &mut [u8], crypto: &mut Cry
let header_dat = unsafe { as_bytes(&header) };
unsafe { ptr::copy_nonoverlapping(header_dat.as_ptr(), buf[pos..].as_mut_ptr(), header_dat.len()) };
pos += header_dat.len();
let nonce_pos = pos;
pos += crypto.nonce_bytes();
let hash_pos = pos;
pos += crypto.auth_bytes();
let crypto_pos = pos;
if let Some(id) = options.network_id {
assert!(buf.len() >= pos + NETWORK_ID_BYTES);
unsafe {
@ -243,13 +239,11 @@ pub fn encode(options: &Options, msg: &Message, buf: &mut [u8], crypto: &mut Cry
}
}
if crypto.method() > 0 {
let (nonce, hash) = crypto.encrypt(&mut buf[crypto_pos..pos]);
assert_eq!(nonce.len(), crypto.nonce_bytes());
assert_eq!(hash.len(), crypto.auth_bytes());
unsafe {
ptr::copy_nonoverlapping(nonce.as_ptr(), buf[nonce_pos..].as_mut_ptr(), crypto.nonce_bytes());
ptr::copy_nonoverlapping(hash.as_ptr(), buf[hash_pos..].as_mut_ptr(), crypto.auth_bytes());
}
let (header, rest) = buf.split_at_mut(mem::size_of::<TopHeader>());
let (nonce, rest) = rest.split_at_mut(crypto.nonce_bytes());
let crypto_start = header.len() + nonce.len();
assert!(rest.len() >= pos - crypto_start + crypto.additional_bytes());
pos = crypto.encrypt(rest, pos-crypto_start, nonce, header) + crypto_start;
}
pos
}
@ -279,7 +273,7 @@ fn encode_message_encrypted() {
let msg = Message::Data(&payload);
let mut buf = [0; 1024];
let size = encode(&mut options, &msg, &mut buf[..], &mut crypto);
assert_eq!(size, 53);
assert_eq!(size, 37);
assert_eq!(&buf[..8], &[118,112,110,1,1,0,0,0]);
let (options2, msg2) = decode(&mut buf[..size], &mut crypto).unwrap();
assert_eq!(options, options2);

49
vpncloud.md
View File

@ -92,10 +92,6 @@ vpncloud(1) -- Peer-to-peer VPN
Display the help.
* `-V`, `--version`:
Print the version and exit.
## DESCRIPTION
@ -198,11 +194,10 @@ vpncloud -t tun -c REMOTE_HOST:PORT --subnet 10.0.0.X/32 --ifup 'ifconfig $IFNAM
primitives are expected to be very secure, their application has not been
reviewed.
The shared key is hashed using *ScryptSalsa208Sha256* to derive a key,
which is used to encrypt the payload of messages using *ChaCha20*. The
authenticity of messages is verified using *HmacSha512256* hashes.
This method only protects the contents of the message (payload, peer list,
etc.) but not the header of each message.
Also, this method does only protect against attacks on single messages but not
which is used to encrypt the payload of messages using *ChaCha20Poly1305*.
The encryption includes an authentication that also protects the header and
all additional headers.
This method does only protect against attacks on single messages but not
on attacks that manipulate the message series itself (i.e. suppress messages,
reorder them, and duplicate them).
@ -224,7 +219,21 @@ Every packet sent over UDP contains the following header (in order):
This field specifies the version and helps nodes to parse the rest of the
header and the packet.
* 2 `reserved bytes` that are currently unused
* 1 byte `crypto method`
This field specifies the method that must be used to decrypt the rest of the
data (additional headers and message contents). The currently supported
methods are:
- Method `0`, **No encryption**: Rest of the data can be read without
decrypting it.
- Method `1`, **ChaCha20Poly1305**: The header is followed by a 8 byte
*nonce*. The rest of the data is encrypted with the
`libsodium::crypto_aead_chacha20poly1305` method, using the 8 byte header
as additional data.
* 1 `reserved byte` that is currently unused
* 1 byte for `flags`
@ -234,7 +243,6 @@ Every packet sent over UDP contains the following header (in order):
order. Currently the following additional headers are supported:
- Bit 1: Network ID
- Bit 2: Crypto information
* 1 byte for the `message type`
@ -246,23 +254,18 @@ Every packet sent over UDP contains the following header (in order):
- Type 2: Initial message
- Type 3: Closing message
After this 8 byte header, the additional headers as specified in the `flags`
field will follow in the order of their respective flag bits.
After this 8 byte header, the rest of the message follows. It is encrypted using
the method specified in the header.
In the decrypted data, the additional headers as specified in the `flags` field
will follow in the order of their respective flag bits.
* **Network ID**:
The network id is encoded as 8 bytes.
* **Crypto information**:
If this header is present, the contents of the message are encrypted and
must have to decrypted before decoding.
This option contains 40 bytes. The first 8 bytes are the **nonce** for this
message and the later 32 bytes are the **authentication hash** of the
message.
After the additional headers, message as specified in the `message type` field
will follow:
After the additional headers, the message as specified in the `message type`
field will follow:
* **Data packet** (message type 0):
This packet contains payload. The format of the data depends on the device