X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fln%2Finbound_payment.rs;h=f9e10880afbe5f5eae122d48220f5b8e5dcd9757;hb=d0f0d9c19f86e5056bbb768e06c6d5f2fb6b925d;hp=dda7cc2b29a125d214e022b18511e4cfc78fd031;hpb=0c250468d632ed6df93d8a9d34389a2cb61eac40;p=rust-lightning

diff --git a/lightning/src/ln/inbound_payment.rs b/lightning/src/ln/inbound_payment.rs
index dda7cc2b..f9e10880 100644
--- a/lightning/src/ln/inbound_payment.rs
+++ b/lightning/src/ln/inbound_payment.rs
@@ -19,7 +19,7 @@ use crate::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
 use crate::ln::msgs;
 use crate::ln::msgs::MAX_VALUE_MSAT;
 use crate::util::chacha20::ChaCha20;
-use crate::util::crypto::hkdf_extract_expand_4x;
+use crate::util::crypto::hkdf_extract_expand_5x;
 use crate::util::errors::APIError;
 use crate::util::logger::Logger;
 
@@ -50,6 +50,8 @@ pub struct ExpandedKey {
 	user_pmt_hash_key: [u8; 32],
 	/// The base key used to derive signing keys and authenticate messages for BOLT 12 Offers.
 	offers_base_key: [u8; 32],
+	/// The key used to encrypt message metadata for BOLT 12 Offers.
+	offers_encryption_key: [u8; 32],
 }
 
 impl ExpandedKey {
@@ -57,20 +59,25 @@ impl ExpandedKey {
 	///
 	/// It is recommended to cache this value and not regenerate it for each new inbound payment.
 	pub fn new(key_material: &KeyMaterial) -> ExpandedKey {
-		let (metadata_key, ldk_pmt_hash_key, user_pmt_hash_key, offers_base_key) =
-			hkdf_extract_expand_4x(b"LDK Inbound Payment Key Expansion", &key_material.0);
+		let (
+			metadata_key,
+			ldk_pmt_hash_key,
+			user_pmt_hash_key,
+			offers_base_key,
+			offers_encryption_key,
+		) = hkdf_extract_expand_5x(b"LDK Inbound Payment Key Expansion", &key_material.0);
 		Self {
 			metadata_key,
 			ldk_pmt_hash_key,
 			user_pmt_hash_key,
 			offers_base_key,
+			offers_encryption_key,
 		}
 	}
 
 	/// Returns an [`HmacEngine`] used to construct [`Offer::metadata`].
 	///
 	/// [`Offer::metadata`]: crate::offers::offer::Offer::metadata
-	#[allow(unused)]
 	pub(crate) fn hmac_for_offer(
 		&self, nonce: Nonce, iv_bytes: &[u8; IV_LEN]
 	) -> HmacEngine<Sha256> {
@@ -79,6 +86,13 @@ impl ExpandedKey {
 		hmac.input(&nonce.0);
 		hmac
 	}
+
+	/// Encrypts or decrypts the given `bytes`. Used for data included in an offer message's
+	/// metadata (e.g., payment id).
+	pub(crate) fn crypt_for_offer(&self, mut bytes: [u8; 32], nonce: Nonce) -> [u8; 32] {
+		ChaCha20::encrypt_single_block_in_place(&self.offers_encryption_key, &nonce.0, &mut bytes);
+		bytes
+	}
 }
 
 /// A 128-bit number used only once.
@@ -88,7 +102,6 @@ impl ExpandedKey {
 ///
 /// [`Offer::metadata`]: crate::offers::offer::Offer::metadata
 /// [`Offer::signing_pubkey`]: crate::offers::offer::Offer::signing_pubkey
-#[allow(unused)]
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub(crate) struct Nonce(pub(crate) [u8; Self::LENGTH]);
 
@@ -271,10 +284,9 @@ fn construct_payment_secret(iv_bytes: &[u8; IV_LEN], metadata_bytes: &[u8; METAD
 	let (iv_slice, encrypted_metadata_slice) = payment_secret_bytes.split_at_mut(IV_LEN);
 	iv_slice.copy_from_slice(iv_bytes);
 
-	let chacha_block = ChaCha20::get_single_block(metadata_key, iv_bytes);
-	for i in 0..METADATA_LEN {
-		encrypted_metadata_slice[i] = chacha_block[i] ^ metadata_bytes[i];
-	}
+	ChaCha20::encrypt_single_block(
+		metadata_key, iv_bytes, encrypted_metadata_slice, metadata_bytes
+	);
 	PaymentSecret(payment_secret_bytes)
 }
 
@@ -406,11 +418,10 @@ fn decrypt_metadata(payment_secret: PaymentSecret, keys: &ExpandedKey) -> ([u8;
 	let (iv_slice, encrypted_metadata_bytes) = payment_secret.0.split_at(IV_LEN);
 	iv_bytes.copy_from_slice(iv_slice);
 
-	let chacha_block = ChaCha20::get_single_block(&keys.metadata_key, &iv_bytes);
 	let mut metadata_bytes: [u8; METADATA_LEN] = [0; METADATA_LEN];
-	for i in 0..METADATA_LEN {
-		metadata_bytes[i] = chacha_block[i] ^ encrypted_metadata_bytes[i];
-	}
+	ChaCha20::encrypt_single_block(
+		&keys.metadata_key, &iv_bytes, &mut metadata_bytes, encrypted_metadata_bytes
+	);
 
 	(iv_bytes, metadata_bytes)
 }