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|
use num_bigint::RandBigInt;
use rand::Rng;
#[derive(Debug)]
pub struct DHKeyPair {
pub p: num_bigint::BigUint,
pub g: num_bigint::BigUint,
pub pubkey: num_bigint::BigUint,
privkey: Option<num_bigint::BigUint>,
}
impl DHKeyPair {
pub fn new(p: num_bigint::BigUint, g: num_bigint::BigUint) -> DHKeyPair {
let privkey = rand::thread_rng().gen_biguint_below(&p);
let pubkey = g.modpow(&privkey, &p);
DHKeyPair {
p,
g,
pubkey,
privkey: Some(privkey),
}
}
pub fn key_exchange(
&self,
other_pubkey: &num_bigint::BigUint,
) -> num_bigint::BigUint {
other_pubkey.modpow(self.privkey.as_ref().unwrap(), &self.p)
}
}
#[derive(Debug)]
pub struct SRPServer {
users: std::collections::HashMap<String, SRPUser>,
sessions: std::collections::HashMap<Vec<u8>, SRPSession>,
n: num_bigint::BigUint,
g: num_bigint::BigUint,
k: num_bigint::BigUint,
}
impl SRPServer {
pub fn new(
n: num_bigint::BigUint,
g: num_bigint::BigUint,
k: num_bigint::BigUint,
) -> SRPServer {
SRPServer {
users: std::collections::HashMap::new(),
sessions: std::collections::HashMap::new(),
n,
g,
k,
}
}
pub fn register(
&mut self,
identity: &str,
salt: &[u8],
verifier: &num_bigint::BigUint,
) {
self.users
.insert(identity.to_string(), SRPUser::new(salt, verifier));
}
pub fn exchange_pubkeys(
&mut self,
user: &str,
a_pub: &num_bigint::BigUint,
) -> (Vec<u8>, Vec<u8>, num_bigint::BigUint) {
let userdata = self.users.get(user).unwrap();
let b_priv = rand::thread_rng().gen_biguint_below(&self.n);
let kv = self.k.clone() * userdata.verifier.clone();
let b_pub = self.g.modpow(&b_priv, &self.n) + kv;
let session = SRPSession {
a_pub: a_pub.clone(),
b_priv: b_priv,
b_pub: b_pub.clone(),
v: userdata.verifier.clone(),
salt: userdata.salt.clone(),
};
let mut session_key = [0; 16];
rand::thread_rng().fill(&mut session_key);
let session_key = session_key.to_vec();
self.sessions.insert(session_key.clone(), session);
(session_key, userdata.salt.to_vec(), b_pub)
}
pub fn verify(&mut self, session: Vec<u8>, hmac: Vec<u8>) -> bool {
let n = &self.n.clone();
let session = self.sessions.get(&session).unwrap();
let uinput =
[session.a_pub.to_bytes_le(), session.b_pub.to_bytes_le()]
.concat();
let uh = crate::sha1::sha1(&uinput);
let u = num_bigint::BigUint::from_bytes_le(&uh[..]);
let s = (session.a_pub.clone() * session.v.modpow(&u, n))
.modpow(&session.b_priv, n);
let k = crate::sha1::sha1(&s.to_bytes_le());
let server_hmac = crate::sha1::sha1_hmac(&k, &session.salt);
hmac == server_hmac
}
}
#[derive(Debug)]
pub struct SRPUser {
salt: Vec<u8>,
verifier: num_bigint::BigUint,
}
impl SRPUser {
pub fn new(salt: &[u8], verifier: &num_bigint::BigUint) -> SRPUser {
SRPUser {
salt: salt.to_vec(),
verifier: verifier.clone(),
}
}
}
#[derive(Debug)]
pub struct SRPSession {
a_pub: num_bigint::BigUint,
b_priv: num_bigint::BigUint,
b_pub: num_bigint::BigUint,
v: num_bigint::BigUint,
salt: Vec<u8>,
}
#[derive(Debug)]
pub struct SRPClient<'a> {
server: &'a mut SRPServer,
}
impl<'a> SRPClient<'a> {
pub fn new(server: &'a mut SRPServer) -> SRPClient<'a> {
SRPClient { server }
}
pub fn register(&mut self, user: &str, pass: &str) {
let mut salt = [0; 16];
rand::thread_rng().fill(&mut salt);
let input = [&salt[..], pass.as_bytes()].concat();
let xh = crate::sha1::sha1(&input);
let x = num_bigint::BigUint::from_bytes_le(&xh[..]);
let v = self.server.g.modpow(&x, &self.server.n);
self.server.register(user, &salt, &v);
}
pub fn key_exchange(
&mut self,
user: &str,
pass: &str,
) -> Option<num_bigint::BigUint> {
let n = &self.server.n.clone();
let g = &self.server.g.clone();
let k = &self.server.k.clone();
let a_priv = rand::thread_rng().gen_biguint_below(n);
let a_pub = g.modpow(&a_priv, n);
let (session, salt, b_pub) =
self.server.exchange_pubkeys(user, &a_pub);
let uinput = [a_pub.to_bytes_le(), b_pub.to_bytes_le()].concat();
let uh = crate::sha1::sha1(&uinput);
let u = num_bigint::BigUint::from_bytes_le(&uh[..]);
let xinput = [salt.clone(), pass.as_bytes().to_vec()].concat();
let xh = crate::sha1::sha1(&xinput);
let x = num_bigint::BigUint::from_bytes_le(&xh[..]);
let s = (b_pub - k * g.modpow(&x, n)).modpow(&(a_priv + u * x), n);
let k = crate::sha1::sha1(&s.to_bytes_le());
let hmac = crate::sha1::sha1_hmac(&k, &salt);
if !self.server.verify(session, hmac.to_vec()) {
return None
}
Some(s)
}
}
|
