DRY shared hkdf_extract_expand code to new module

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

diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
index 4e493546c23e7be9ddc9a31414e137c14c27be5e..c79076b59a48db7df9e946d2f43bc70cc22c8409 100644 (file)
--- a/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@ -81,6 +81,7 @@ mod inbound_payment {
        use ln::msgs;
        use ln::msgs::MAX_VALUE_MSAT;
        use util::chacha20::ChaCha20;
+       use util::crypto::hkdf_extract_expand_thrice;
        use util::logger::Logger;
 
        use core::convert::TryInto;
@@ -112,7 +113,13 @@ mod inbound_payment {
 
        impl ExpandedKey {
                pub(super) fn new(key_material: &KeyMaterial) -> ExpandedKey {
-                       hkdf_extract_expand(b"LDK Inbound Payment Key Expansion", &key_material)
+                       let (metadata_key, ldk_pmt_hash_key, user_pmt_hash_key) =
+                               hkdf_extract_expand_thrice(b"LDK Inbound Payment Key Expansion", &key_material.0);
+                       Self {
+                               metadata_key,
+                               ldk_pmt_hash_key,
+                               user_pmt_hash_key,
+                       }
                }
        }
 
@@ -330,31 +337,6 @@ mod inbound_payment {
                }
                return Ok(PaymentPreimage(decoded_payment_preimage))
        }
-
-       fn hkdf_extract_expand(salt: &[u8], ikm: &KeyMaterial) -> ExpandedKey {
-               let mut hmac = HmacEngine::<Sha256>::new(salt);
-               hmac.input(&ikm.0);
-               let prk = Hmac::from_engine(hmac).into_inner();
-               let mut hmac = HmacEngine::<Sha256>::new(&prk[..]);
-               hmac.input(&[1; 1]);
-               let metadata_key = Hmac::from_engine(hmac).into_inner();
-
-               let mut hmac = HmacEngine::<Sha256>::new(&prk[..]);
-               hmac.input(&metadata_key);
-               hmac.input(&[2; 1]);
-               let ldk_pmt_hash_key = Hmac::from_engine(hmac).into_inner();
-
-               let mut hmac = HmacEngine::<Sha256>::new(&prk[..]);
-               hmac.input(&ldk_pmt_hash_key);
-               hmac.input(&[3; 1]);
-               let user_pmt_hash_key = Hmac::from_engine(hmac).into_inner();
-
-               ExpandedKey {
-                       metadata_key,
-                       ldk_pmt_hash_key,
-                       user_pmt_hash_key,
-               }
-       }
 }
 
 // We hold various information about HTLC relay in the HTLC objects in Channel itself: