X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fln%2Fpeer_channel_encryptor.rs;h=8569fa60ffef46268fd020578dc22cb1e455649d;hb=103180df8f3ab77d1d5282bc8546b3072aaa55ec;hp=071ef8a9dd6ae12b032928b646a4caf6587bcb1c;hpb=6cb9919f0c84f61eb9281617ee3816c73e081747;p=rust-lightning diff --git a/lightning/src/ln/peer_channel_encryptor.rs b/lightning/src/ln/peer_channel_encryptor.rs index 071ef8a9..8569fa60 100644 --- a/lightning/src/ln/peer_channel_encryptor.rs +++ b/lightning/src/ln/peer_channel_encryptor.rs @@ -34,6 +34,10 @@ use core::ops::Deref; /// and [BOLT-1](https://github.com/lightning/bolts/blob/master/01-messaging.md#lightning-message-format): pub const LN_MAX_MSG_LEN: usize = ::core::u16::MAX as usize; // Must be equal to 65535 +/// The (rough) size buffer to pre-allocate when encoding a message. Messages should reliably be +/// smaller than this size by at least 32 bytes or so. +pub const MSG_BUF_ALLOC_SIZE: usize = 2048; + // Sha256("Noise_XK_secp256k1_ChaChaPoly_SHA256") const NOISE_CK: [u8; 32] = [0x26, 0x40, 0xf5, 0x2e, 0xeb, 0xcd, 0x9e, 0x88, 0x29, 0x58, 0x95, 0x1c, 0x79, 0x42, 0x50, 0xee, 0xdb, 0x28, 0x00, 0x2c, 0x05, 0xd7, 0xdc, 0x2e, 0xa0, 0xf1, 0x95, 0x40, 0x60, 0x42, 0xca, 0xf1]; // Sha256(NOISE_CK || "lightning") @@ -165,6 +169,18 @@ impl PeerChannelEncryptor { res.extend_from_slice(&tag); } + fn decrypt_in_place_with_ad(inout: &mut [u8], n: u64, key: &[u8; 32], h: &[u8]) -> Result<(), LightningError> { + let mut nonce = [0; 12]; + nonce[4..].copy_from_slice(&n.to_le_bytes()[..]); + + let mut chacha = ChaCha20Poly1305RFC::new(key, &nonce, h); + let (inout, tag) = inout.split_at_mut(inout.len() - 16); + if chacha.check_decrypt_in_place(inout, tag).is_err() { + return Err(LightningError{err: "Bad MAC".to_owned(), action: msgs::ErrorAction::DisconnectPeer{ msg: None }}); + } + Ok(()) + } + #[inline] fn decrypt_with_ad(res: &mut[u8], n: u64, key: &[u8; 32], h: &[u8], cyphertext: &[u8]) -> Result<(), LightningError> { let mut nonce = [0; 12]; @@ -411,16 +427,20 @@ impl PeerChannelEncryptor { Ok(self.their_node_id.unwrap().clone()) } - /// Encrypts the given pre-serialized message, returning the encrypted version. - /// panics if msg.len() > 65535 or Noise handshake has not finished. - pub fn encrypt_buffer(&mut self, msg: &[u8]) -> Vec { - if msg.len() > LN_MAX_MSG_LEN { + /// Builds sendable bytes for a message. + /// + /// `msgbuf` must begin with 16 + 2 dummy/0 bytes, which will be filled with the encrypted + /// message length and its MAC. It should then be followed by the message bytes themselves + /// (including the two byte message type). + /// + /// For effeciency, the [`Vec::capacity`] should be at least 16 bytes larger than the + /// [`Vec::len`], to avoid reallocating for the message MAC, which will be appended to the vec. + fn encrypt_message_with_header_0s(&mut self, msgbuf: &mut Vec) { + let msg_len = msgbuf.len() - 16 - 2; + if msg_len > LN_MAX_MSG_LEN { panic!("Attempted to encrypt message longer than 65535 bytes!"); } - let mut res = Vec::with_capacity(msg.len() + 16*2 + 2); - res.resize(msg.len() + 16*2 + 2, 0); - match self.noise_state { NoiseState::Finished { ref mut sk, ref mut sn, ref mut sck, rk: _, rn: _, rck: _ } => { if *sn >= 1000 { @@ -430,16 +450,21 @@ impl PeerChannelEncryptor { *sn = 0; } - Self::encrypt_with_ad(&mut res[0..16+2], *sn, sk, &[0; 0], &(msg.len() as u16).to_be_bytes()); + Self::encrypt_with_ad(&mut msgbuf[0..16+2], *sn, sk, &[0; 0], &(msg_len as u16).to_be_bytes()); *sn += 1; - Self::encrypt_with_ad(&mut res[16+2..], *sn, sk, &[0; 0], msg); + Self::encrypt_in_place_with_ad(msgbuf, 16+2, *sn, sk, &[0; 0]); *sn += 1; }, _ => panic!("Tried to encrypt a message prior to noise handshake completion"), } + } - res + /// Encrypts the given pre-serialized message, returning the encrypted version. + /// panics if msg.len() > 65535 or Noise handshake has not finished. + pub fn encrypt_buffer(&mut self, mut msg: MessageBuf) -> Vec { + self.encrypt_message_with_header_0s(&mut msg.0); + msg.0 } /// Encrypts the given message, returning the encrypted version. @@ -448,33 +473,11 @@ impl PeerChannelEncryptor { pub fn encrypt_message(&mut self, message: &M) -> Vec { // Allocate a buffer with 2KB, fitting most common messages. Reserve the first 16+2 bytes // for the 2-byte message type prefix and its MAC. - let mut res = VecWriter(Vec::with_capacity(2048)); + let mut res = VecWriter(Vec::with_capacity(MSG_BUF_ALLOC_SIZE)); res.0.resize(16 + 2, 0); wire::write(message, &mut res).expect("In-memory messages must never fail to serialize"); - let msg_len = res.0.len() - 16 - 2; - if msg_len > LN_MAX_MSG_LEN { - panic!("Attempted to encrypt message longer than 65535 bytes!"); - } - - match self.noise_state { - NoiseState::Finished { ref mut sk, ref mut sn, ref mut sck, rk: _, rn: _, rck: _ } => { - if *sn >= 1000 { - let (new_sck, new_sk) = hkdf_extract_expand_twice(sck, sk); - *sck = new_sck; - *sk = new_sk; - *sn = 0; - } - - Self::encrypt_with_ad(&mut res.0[0..16+2], *sn, sk, &[0; 0], &(msg_len as u16).to_be_bytes()); - *sn += 1; - - Self::encrypt_in_place_with_ad(&mut res.0, 16+2, *sn, sk, &[0; 0]); - *sn += 1; - }, - _ => panic!("Tried to encrypt a message prior to noise handshake completion"), - } - + self.encrypt_message_with_header_0s(&mut res.0); res.0 } @@ -501,21 +504,20 @@ impl PeerChannelEncryptor { } } - /// Decrypts the given message. + /// Decrypts the given message up to msg.len() - 16. Bytes after msg.len() - 16 will be left + /// undefined (as they contain the Poly1305 tag bytes). + /// /// panics if msg.len() > 65535 + 16 - pub fn decrypt_message(&mut self, msg: &[u8]) -> Result, LightningError> { + pub fn decrypt_message(&mut self, msg: &mut [u8]) -> Result<(), LightningError> { if msg.len() > LN_MAX_MSG_LEN + 16 { panic!("Attempted to decrypt message longer than 65535 + 16 bytes!"); } match self.noise_state { NoiseState::Finished { sk: _, sn: _, sck: _, ref rk, ref mut rn, rck: _ } => { - let mut res = Vec::with_capacity(msg.len() - 16); - res.resize(msg.len() - 16, 0); - Self::decrypt_with_ad(&mut res[..], *rn, rk, &[0; 0], msg)?; + Self::decrypt_in_place_with_ad(&mut msg[..], *rn, rk, &[0; 0])?; *rn += 1; - - Ok(res) + Ok(()) }, _ => panic!("Tried to decrypt a message prior to noise handshake completion"), } @@ -542,9 +544,30 @@ impl PeerChannelEncryptor { } } +/// A buffer which stores an encoded message (including the two message-type bytes) with some +/// padding to allow for future encryption/MACing. +pub struct MessageBuf(Vec); +impl MessageBuf { + /// Creates a new buffer from an encoded message (i.e. the two message-type bytes followed by + /// the message contents). + /// + /// Panics if the message is longer than 2^16. + pub fn from_encoded(encoded_msg: &[u8]) -> Self { + if encoded_msg.len() > LN_MAX_MSG_LEN { + panic!("Attempted to encrypt message longer than 65535 bytes!"); + } + // In addition to the message (continaing the two message type bytes), we also have to add + // the message length header (and its MAC) and the message MAC. + let mut res = Vec::with_capacity(encoded_msg.len() + 16*2 + 2); + res.resize(encoded_msg.len() + 16 + 2, 0); + res[16 + 2..].copy_from_slice(&encoded_msg); + Self(res) + } +} + #[cfg(test)] mod tests { - use super::LN_MAX_MSG_LEN; + use super::{MessageBuf, LN_MAX_MSG_LEN}; use bitcoin::secp256k1::{PublicKey, SecretKey}; use bitcoin::secp256k1::Secp256k1; @@ -760,12 +783,11 @@ mod tests { for i in 0..1005 { let msg = [0x68, 0x65, 0x6c, 0x6c, 0x6f]; - let res = outbound_peer.encrypt_buffer(&msg); + let mut res = outbound_peer.encrypt_buffer(MessageBuf::from_encoded(&msg)); assert_eq!(res.len(), 5 + 2*16 + 2); let len_header = res[0..2+16].to_vec(); assert_eq!(inbound_peer.decrypt_length_header(&len_header[..]).unwrap() as usize, msg.len()); - assert_eq!(inbound_peer.decrypt_message(&res[2+16..]).unwrap()[..], msg[..]); if i == 0 { assert_eq!(res, hex::decode("cf2b30ddf0cf3f80e7c35a6e6730b59fe802473180f396d88a8fb0db8cbcf25d2f214cf9ea1d95").unwrap()); @@ -780,6 +802,9 @@ mod tests { } else if i == 1001 { assert_eq!(res, hex::decode("2ecd8c8a5629d0d02ab457a0fdd0f7b90a192cd46be5ecb6ca570bfc5e268338b1a16cf4ef2d36").unwrap()); } + + inbound_peer.decrypt_message(&mut res[2+16..]).unwrap(); + assert_eq!(res[2 + 16..res.len() - 16], msg[..]); } } @@ -794,7 +819,7 @@ mod tests { fn max_message_len_encryption() { let mut outbound_peer = get_outbound_peer_for_initiator_test_vectors(); let msg = [4u8; LN_MAX_MSG_LEN + 1]; - outbound_peer.encrypt_buffer(&msg); + outbound_peer.encrypt_buffer(MessageBuf::from_encoded(&msg)); } #[test] @@ -803,7 +828,7 @@ mod tests { let mut inbound_peer = get_inbound_peer_for_test_vectors(); // MSG should not exceed LN_MAX_MSG_LEN + 16 - let msg = [4u8; LN_MAX_MSG_LEN + 17]; - inbound_peer.decrypt_message(&msg).unwrap(); + let mut msg = [4u8; LN_MAX_MSG_LEN + 17]; + inbound_peer.decrypt_message(&mut msg).unwrap(); } }