DRY shared hkdf_extract_expand code to new module

[rust-lightning] / lightning / src / ln / peer_channel_encryptor.rs

diff --git a/lightning/src/ln/peer_channel_encryptor.rs b/lightning/src/ln/peer_channel_encryptor.rs
index 7b42c68a578154aedcc0116cffac9c1a4ee5d799..fbd32526ea658470f810c487bcb88da608904e8b 100644 (file)
--- a/lightning/src/ln/peer_channel_encryptor.rs
+++ b/lightning/src/ln/peer_channel_encryptor.rs
@@ -12,7 +12,7 @@ use prelude::*;
 use ln::msgs::LightningError;
 use ln::msgs;
 
-use bitcoin::hashes::{Hash, HashEngine, Hmac, HmacEngine};
+use bitcoin::hashes::{Hash, HashEngine};
 use bitcoin::hashes::sha256::Hash as Sha256;
 
 use bitcoin::secp256k1::Secp256k1;
@@ -21,6 +21,7 @@ use bitcoin::secp256k1::ecdh::SharedSecret;
 use bitcoin::secp256k1;
 
 use util::chacha20poly1305rfc::ChaCha20Poly1305RFC;
+use util::crypto::hkdf_extract_expand_twice;
 use bitcoin::hashes::hex::ToHex;
 
 /// Maximum Lightning message data length according to
@@ -160,22 +161,9 @@ impl PeerChannelEncryptor {
                Ok(())
        }
 
-       fn hkdf_extract_expand(salt: &[u8], ikm: &[u8]) -> ([u8; 32], [u8; 32]) {
-               let mut hmac = HmacEngine::<Sha256>::new(salt);
-               hmac.input(ikm);
-               let prk = Hmac::from_engine(hmac).into_inner();
-               let mut hmac = HmacEngine::<Sha256>::new(&prk[..]);
-               hmac.input(&[1; 1]);
-               let t1 = Hmac::from_engine(hmac).into_inner();
-               let mut hmac = HmacEngine::<Sha256>::new(&prk[..]);
-               hmac.input(&t1);
-               hmac.input(&[2; 1]);
-               (t1, Hmac::from_engine(hmac).into_inner())
-       }
-
        #[inline]
        fn hkdf(state: &mut BidirectionalNoiseState, ss: SharedSecret) -> [u8; 32] {
-               let (t1, t2) = Self::hkdf_extract_expand(&state.ck, &ss[..]);
+               let (t1, t2) = hkdf_extract_expand_twice(&state.ck, &ss[..]);
                state.ck = t1;
                t2
        }
@@ -311,7 +299,7 @@ impl PeerChannelEncryptor {
                                                let temp_k = PeerChannelEncryptor::hkdf(bidirectional_state, ss);
 
                                                PeerChannelEncryptor::encrypt_with_ad(&mut res[50..], 0, &temp_k, &bidirectional_state.h, &[0; 0]);
-                                               final_hkdf = Self::hkdf_extract_expand(&bidirectional_state.ck, &[0; 0]);
+                                               final_hkdf = hkdf_extract_expand_twice(&bidirectional_state.ck, &[0; 0]);
                                                ck = bidirectional_state.ck.clone();
                                                res
                                        },
@@ -365,7 +353,7 @@ impl PeerChannelEncryptor {
                                                let temp_k = PeerChannelEncryptor::hkdf(bidirectional_state, ss);
 
                                                PeerChannelEncryptor::decrypt_with_ad(&mut [0; 0], 0, &temp_k, &bidirectional_state.h, &act_three[50..])?;
-                                               final_hkdf = Self::hkdf_extract_expand(&bidirectional_state.ck, &[0; 0]);
+                                               final_hkdf = hkdf_extract_expand_twice(&bidirectional_state.ck, &[0; 0]);
                                                ck = bidirectional_state.ck.clone();
                                        },
                                        _ => panic!("Wrong direction for act"),
@@ -399,7 +387,7 @@ impl PeerChannelEncryptor {
                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) = Self::hkdf_extract_expand(sck, sk);
+                                       let (new_sck, new_sk) = hkdf_extract_expand_twice(sck, sk);
                                        *sck = new_sck;
                                        *sk = new_sk;
                                        *sn = 0;
@@ -425,7 +413,7 @@ impl PeerChannelEncryptor {
                match self.noise_state {
                        NoiseState::Finished { sk: _, sn: _, sck: _, ref mut rk, ref mut rn, ref mut rck } => {
                                if *rn >= 1000 {
-                                       let (new_rck, new_rk) = Self::hkdf_extract_expand(rck, rk);
+                                       let (new_rck, new_rk) = hkdf_extract_expand_twice(rck, rk);
                                        *rck = new_rck;
                                        *rk = new_rk;
                                        *rn = 0;