1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
|
use std::time::{Duration, Instant};
use blake2::Blake2s;
use subtle::ConstantTimeEq;
use x25519_dalek::PublicKey;
use super::messages::{CookieReply, MacsFooter};
use super::types::HandshakeError;
const LABEL_MAC1: &[u8] = b"mac1----";
const LABEL_COOKIE: &[u8] = b"cookie--";
const SIZE_COOKIE: usize = 16;
const SIZE_MAC: usize = 16; // blake2s-mac128
const SECS_COOKIE_UPDATE: u64 = 120;
macro_rules! HASH {
( $($input:expr),* ) => {{
use blake2::Digest;
let mut hsh = Blake2s::new();
$(
hsh.input($input);
)*
hsh.result()
}};
}
macro_rules! MAC {
( $key:expr, $($input:expr),* ) => {{
use blake2::VarBlake2s;
use digest::Input;
use digest::VariableOutput;
let mut tag = [0u8; SIZE_MAC];
let mut mac = VarBlake2s::new_keyed($key, SIZE_MAC);
$(
mac.input($input);
)*
mac.variable_result(|buf| tag.copy_from_slice(buf));
tag
}};
}
struct Cookie {
value: [u8; 16],
birth: Instant,
}
pub struct Generator {
mac1_key: [u8; 32],
last_mac1: Option<[u8; 16]>,
cookie: Option<Cookie>,
}
impl Generator {
/// Initalize a new mac field generator
///
/// # Arguments
///
/// - pk: The public key of the peer to which the generator is associated
///
/// # Returns
///
/// A freshly initated generator
pub fn new(pk: PublicKey) -> Generator {
Generator {
mac1_key: HASH!(LABEL_MAC1, pk.as_bytes()).into(),
last_mac1: None,
cookie: None,
}
}
/// Process a CookieReply message
///
/// # Arguments
///
/// - reply: CookieReply to process
///
/// # Returns
///
/// Can fail if the cookie reply fails to validate
/// (either indicating that it is outdated or malformed)
pub fn process(&mut self, reply: &CookieReply) -> Option<HandshakeError> {
self.cookie = Some(Cookie {
birth: Instant::now(),
value: reply.f_cookie,
});
None
}
/// Generate both mac fields for an inner message
///
/// # Arguments
///
/// - inner: A byteslice representing the inner message to be covered
/// - macs: The destination mac footer for the resulting macs
pub fn generate(&mut self, inner: &[u8], macs: &mut MacsFooter) {
macs.f_mac1 = MAC!(&self.mac1_key, inner);
macs.f_mac2 = match &self.cookie {
Some(cookie) => {
if cookie.birth.elapsed() > Duration::from_secs(SECS_COOKIE_UPDATE) {
self.cookie = None;
[0u8; SIZE_MAC]
} else {
MAC!(&cookie.value, inner, macs.f_mac1)
}
}
None => [0u8; SIZE_MAC],
};
self.last_mac1 = Some(macs.f_mac1);
}
}
pub struct Validator {
mac1_key: [u8; 32],
}
impl Validator {
pub fn new(pk: PublicKey) -> Validator {
Validator {
mac1_key: HASH!(LABEL_MAC1, pk.as_bytes()).into(),
}
}
pub fn check_mac1(&self, inner: &[u8], macs: &MacsFooter) -> Result<(), HandshakeError> {
let valid_mac1: bool = MAC!(&self.mac1_key, inner).ct_eq(&macs.f_mac1).into();
if !valid_mac1 {
Err(HandshakeError::InvalidMac1)
} else {
Ok(())
}
}
}
|
