hardcoresushi/async-psec
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Use handshake peer IV without calling iv_to_nonce

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This commit is contained in:
Matéo Duparc 2021-05-31 14:30:45 +02:00
parent 1b280f2332
commit f9cd06f30f
Signed by: hardcoresushi
GPG Key ID: 007F84120107191E
3 changed files with 18 additions and 18 deletions
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8
Cargo.toml
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@ -1,6 +1,6 @@
[package]
name = "async-psec"
version = "0.3.0"
version = "0.3.1"
authors = ["Hardcore Sushi <hardcore.sushi@disroot.org>"]
edition = "2018"
description = "Asynchronous PSEC implementation"
@ -11,11 +11,11 @@ keywords = ["psec", "async", "p2p"]
categories = ["asynchronous", "cryptography", "network-programming"]
[dependencies]
tokio = {version = "1.6", features = ["net", "io-util"]}
tokio = { version = "1.6", features = ["net", "io-util"] }
async-trait = "0.1"
rand = "0.7"
x25519-dalek = "1.1" #for shared secret
ed25519-dalek = "1.0" #for singing
ed25519-dalek = "1.0" #for singatures
sha2 = "0.9"
aes-gcm = "0.9"
hkdf = "0.11"
@ -23,7 +23,7 @@ hmac = "0.11"
[dev-dependencies]
hex = "0.4"
tokio = {version = "1.6", features = ["rt-multi-thread", "macros"]}
tokio = { version = "1.6", features = ["rt-multi-thread", "macros"] }
[features]
split = []

1
src/crypto.rs
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@ -6,7 +6,6 @@ use sha2::Sha384;
pub const HASH_OUTPUT_LEN: usize = 48; //SHA384
const KEY_LEN: usize = 16;
pub const IV_LEN: usize = 12;
pub const AES_TAG_LEN: usize = 16;
pub fn iv_to_nonce(iv: &[u8], counter: &mut usize) -> Vec<u8> {
let mut counter_bytes = vec![0; 4];

27
src/lib.rs
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@ -55,12 +55,13 @@ use sha2::{Sha384, Digest};
use aes_gcm::{Aes128Gcm, aead::Aead, NewAead, aead::Payload, Nonce};
use crypto::{HandshakeKeys, ApplicationKeys};
const AES_TAG_LEN: usize = 16;
const RANDOM_LEN: usize = 64;
const MESSAGE_LEN_LEN: usize = 4;
type MessageLenType = u32;
const DEFAULT_PADDED_MAX_SIZE: usize = 32768000;
const DEFAULT_MAX_RECV_SIZE: usize = MESSAGE_LEN_LEN + DEFAULT_PADDED_MAX_SIZE + crypto::AES_TAG_LEN;
const DEFAULT_MAX_RECV_SIZE: usize = MESSAGE_LEN_LEN + DEFAULT_PADDED_MAX_SIZE + AES_TAG_LEN;
/// The length of a PSEC public key, in bytes.
pub const PUBLIC_KEY_LENGTH: usize = ed25519_dalek::PUBLIC_KEY_LENGTH;
@ -189,7 +190,7 @@ async fn encrypt_and_send<T: AsyncWriteExt + Unpin>(writer: &mut T, local_cipher
async fn receive_and_decrypt<T: AsyncReadExt + Unpin>(reader: &mut T, peer_cipher: &Aes128Gcm, peer_iv: &[u8], peer_counter: &mut usize, max_recv_size: usize) -> Result<Vec<u8>, PsecError> {
let mut message_len = [0; MESSAGE_LEN_LEN];
receive(reader, &mut message_len).await?;
let recv_len = MessageLenType::from_be_bytes(message_len) as usize + crypto::AES_TAG_LEN;
let recv_len = MessageLenType::from_be_bytes(message_len) as usize + AES_TAG_LEN;
if recv_len <= max_recv_size {
let mut cipher_text = vec![0; recv_len];
let mut read = 0;
@ -219,7 +220,7 @@ fn compute_max_recv_size(size: usize, is_raw_size: bool) -> usize {
while max_padded_size < max_not_padded_size {
max_padded_size *= 2;
}
max_padded_size+crypto::AES_TAG_LEN
max_padded_size+AES_TAG_LEN
}
}
@ -530,6 +531,7 @@ impl Session {
pub async fn do_handshake(&mut self, identity: &Identity) -> Result<(), PsecError> {
let mut handshake_sent_buff = Vec::new();
let mut handshake_recv_buff = Vec::new();
//ECDHE initial exchange
//generate random bytes
let mut handshake_buffer = [0; RANDOM_LEN+PUBLIC_KEY_LENGTH];
@ -538,18 +540,18 @@ impl Session {
let ephemeral_secret = x25519_dalek::EphemeralSecret::new(OsRng);
let ephemeral_public_key = x25519_dalek::PublicKey::from(&ephemeral_secret);
handshake_buffer[RANDOM_LEN..].copy_from_slice(&ephemeral_public_key.to_bytes());
//exchange public keys
self.handshake_write(&handshake_buffer, &mut handshake_sent_buff).await?;
self.handshake_read(&mut handshake_buffer, &mut handshake_recv_buff).await?;
let peer_ephemeral_public_key = slice_to_public_key(&handshake_buffer[RANDOM_LEN..]);
//computing handshake keys
//compute handshake keys
let i_am_bob = handshake_sent_buff < handshake_recv_buff; //mutual consensus for keys attribution
let handshake_hash = Session::hash_handshake(i_am_bob, &handshake_sent_buff, &handshake_recv_buff);
let shared_secret = ephemeral_secret.diffie_hellman(&peer_ephemeral_public_key);
let handshake_keys = HandshakeKeys::derive_keys(shared_secret.to_bytes(), handshake_hash, i_am_bob);
//encrypted handshake
//random bytes, public key & ephemeral public key signature
//authentication
//create auth_msg: random bytes, public key & ephemeral public key signature
let mut auth_msg = [0; RANDOM_LEN+PUBLIC_KEY_LENGTH+SIGNATURE_LENGTH];
OsRng.fill_bytes(&mut auth_msg[..RANDOM_LEN]);
auth_msg[RANDOM_LEN..RANDOM_LEN+PUBLIC_KEY_LENGTH].copy_from_slice(&identity.public.to_bytes());
@ -559,27 +561,26 @@ impl Session {
let encrypted_auth_msg = local_cipher.encrypt(Nonce::from_slice(&handshake_keys.local_iv), auth_msg.as_ref()).unwrap();
self.handshake_write(&encrypted_auth_msg, &mut handshake_sent_buff).await?;
let mut encrypted_peer_auth_msg = [0; RANDOM_LEN+PUBLIC_KEY_LENGTH+SIGNATURE_LENGTH+crypto::AES_TAG_LEN];
let mut encrypted_peer_auth_msg = [0; RANDOM_LEN+PUBLIC_KEY_LENGTH+SIGNATURE_LENGTH+AES_TAG_LEN];
self.handshake_read(&mut encrypted_peer_auth_msg, &mut handshake_recv_buff).await?;
//decrypt peer_auth_msg
let peer_cipher = Aes128Gcm::new_from_slice(&handshake_keys.peer_key).unwrap();
let mut peer_handshake_counter = 0;
let peer_nonce = crypto::iv_to_nonce(&handshake_keys.peer_iv, &mut peer_handshake_counter);
match peer_cipher.decrypt(Nonce::from_slice(&peer_nonce), encrypted_peer_auth_msg.as_ref()) {
match peer_cipher.decrypt(Nonce::from_slice(&handshake_keys.peer_iv), encrypted_peer_auth_msg.as_ref()) {
Ok(peer_auth_msg) => {
//verify ephemeral public key signature
self.peer_public_key = Some(peer_auth_msg[RANDOM_LEN..RANDOM_LEN+PUBLIC_KEY_LENGTH].try_into().unwrap());
let peer_public_key = ed25519_dalek::PublicKey::from_bytes(&self.peer_public_key.unwrap()).unwrap();
let peer_signature = Signature::from_bytes(&peer_auth_msg[RANDOM_LEN+PUBLIC_KEY_LENGTH..]).unwrap();
if peer_public_key.verify(peer_ephemeral_public_key.as_bytes(), &peer_signature).is_ok() {
//compute handshake finished
let handshake_hash = Session::hash_handshake(i_am_bob, &handshake_sent_buff, &handshake_recv_buff);
//sending handshake finished
let handshake_finished = crypto::compute_handshake_finished(handshake_keys.local_handshake_traffic_secret, handshake_hash);
self.send(&handshake_finished).await?;
//verify handshake finished
let mut peer_handshake_finished = [0; crypto::HASH_OUTPUT_LEN];
self.receive(&mut peer_handshake_finished).await?;
if crypto::verify_handshake_finished(peer_handshake_finished, handshake_keys.peer_handshake_traffic_secret, handshake_hash) {
//computing application keys
//compute application keys
let application_keys = ApplicationKeys::derive_keys(handshake_keys.handshake_secret, handshake_hash, i_am_bob);
self.init_ciphers(application_keys);
return Ok(());