Move Nonce to a separate offers sub-module

Nonce is used when constructing Offer::metadata and will soon be need
when constructing BlindedPath for use in authentication. Move it to
separate module now that it is public and will be more widely used.

Author: jkczyz

lightning/src/ln/inbound_payment.rs

@@ -19,6 +19,7 @@ use crate::crypto::utils::hkdf_extract_expand_5x;
 use crate::ln::types::{PaymentHash, PaymentPreimage, PaymentSecret};
 use crate::ln::msgs;
 use crate::ln::msgs::MAX_VALUE_MSAT;
+use crate::offers::nonce::Nonce;
 use crate::sign::{KeyMaterial, EntropySource};
 use crate::util::errors::APIError;
 use crate::util::logger::Logger;
@@ -97,53 +98,6 @@ impl ExpandedKey {
 	}
 }
 
-/// A 128-bit number used only once.
-///
-/// Needed when constructing [`Offer::metadata`] and deriving [`Offer::signing_pubkey`] from
-/// [`ExpandedKey`]. Must not be reused for any other derivation without first hashing.
-///
-/// [`Offer::metadata`]: crate::offers::offer::Offer::metadata
-/// [`Offer::signing_pubkey`]: crate::offers::offer::Offer::signing_pubkey
-#[derive(Clone, Copy, Debug, PartialEq)]
-pub struct Nonce(pub(crate) [u8; Self::LENGTH]);
-
-impl Nonce {
-	/// Number of bytes in the nonce.
-	pub const LENGTH: usize = 16;
-
-	/// Creates a `Nonce` from the given [`EntropySource`].
-	pub fn from_entropy_source<ES: Deref>(entropy_source: ES) -> Self
-	where
-		ES::Target: EntropySource,
-	{
-		let mut bytes = [0u8; Self::LENGTH];
-		let rand_bytes = entropy_source.get_secure_random_bytes();
-		bytes.copy_from_slice(&rand_bytes[..Self::LENGTH]);
-
-		Nonce(bytes)
-	}
-
-	/// Returns a slice of the underlying bytes of size [`Nonce::LENGTH`].
-	pub fn as_slice(&self) -> &[u8] {
-		&self.0
-	}
-}
-
-impl TryFrom<&[u8]> for Nonce {
-	type Error = ();
-
-	fn try_from(bytes: &[u8]) -> Result<Self, ()> {
-		if bytes.len() != Self::LENGTH {
-			return Err(());
-		}
-
-		let mut copied_bytes = [0u8; Self::LENGTH];
-		copied_bytes.copy_from_slice(bytes);
-
-		Ok(Self(copied_bytes))
-	}
-}
-
 enum Method {
 	LdkPaymentHash = 0,
 	UserPaymentHash = 1,

lightning/src/offers/invoice_request.rs

@@ -68,10 +68,11 @@ use crate::blinded_path::BlindedPath;
 use crate::ln::types::PaymentHash;
 use crate::ln::channelmanager::PaymentId;
 use crate::ln::features::InvoiceRequestFeatures;
-use crate::ln::inbound_payment::{ExpandedKey, IV_LEN, Nonce};
+use crate::ln::inbound_payment::{ExpandedKey, IV_LEN};
 use crate::ln::msgs::DecodeError;
 use crate::offers::invoice::BlindedPayInfo;
 use crate::offers::merkle::{SignError, SignFn, SignatureTlvStream, SignatureTlvStreamRef, TaggedHash, self};
+use crate::offers::nonce::Nonce;
 use crate::offers::offer::{Offer, OfferContents, OfferId, OfferTlvStream, OfferTlvStreamRef};
 use crate::offers::parse::{Bolt12ParseError, ParsedMessage, Bolt12SemanticError};
 use crate::offers::payer::{PayerContents, PayerTlvStream, PayerTlvStreamRef};

lightning/src/offers/mod.rs

@@ -20,6 +20,7 @@ pub mod invoice_error;
 mod invoice_macros;
 pub mod invoice_request;
 pub mod merkle;
+pub mod nonce;
 pub mod parse;
 mod payer;
 pub mod refund;

lightning/src/offers/nonce.rs

@@ -0,0 +1,64 @@
+// This file is Copyright its original authors, visible in version control
+// history.
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
+// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
+
+//! A number used only once.
+
+use core::ops::Deref;
+use crate::sign::EntropySource;
+
+#[allow(unused_imports)]
+use crate::prelude::*;
+
+/// A 128-bit number used only once.
+///
+/// Needed when constructing [`Offer::metadata`] and deriving [`Offer::signing_pubkey`] from
+/// [`ExpandedKey`]. Must not be reused for any other derivation without first hashing.
+///
+/// [`Offer::metadata`]: crate::offers::offer::Offer::metadata
+/// [`Offer::signing_pubkey`]: crate::offers::offer::Offer::signing_pubkey
+/// [`ExpandedKey`]: crate::ln::inbound_payment::ExpandedKey
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct Nonce(pub(crate) [u8; Self::LENGTH]);
+
+impl Nonce {
+	/// Number of bytes in the nonce.
+	pub const LENGTH: usize = 16;
+
+	/// Creates a `Nonce` from the given [`EntropySource`].
+	pub fn from_entropy_source<ES: Deref>(entropy_source: ES) -> Self
+	where
+		ES::Target: EntropySource,
+	{
+		let mut bytes = [0u8; Self::LENGTH];
+		let rand_bytes = entropy_source.get_secure_random_bytes();
+		bytes.copy_from_slice(&rand_bytes[..Self::LENGTH]);
+
+		Nonce(bytes)
+	}
+
+	/// Returns a slice of the underlying bytes of size [`Nonce::LENGTH`].
+	pub fn as_slice(&self) -> &[u8] {
+		&self.0
+	}
+}
+
+impl TryFrom<&[u8]> for Nonce {
+	type Error = ();
+
+	fn try_from(bytes: &[u8]) -> Result<Self, ()> {
+		if bytes.len() != Self::LENGTH {
+			return Err(());
+		}
+
+		let mut copied_bytes = [0u8; Self::LENGTH];
+		copied_bytes.copy_from_slice(bytes);
+
+		Ok(Self(copied_bytes))
+	}
+}

lightning/src/offers/offer.rs

@@ -90,9 +90,10 @@ use crate::io;
 use crate::blinded_path::BlindedPath;
 use crate::ln::channelmanager::PaymentId;
 use crate::ln::features::OfferFeatures;
-use crate::ln::inbound_payment::{ExpandedKey, IV_LEN, Nonce};
+use crate::ln::inbound_payment::{ExpandedKey, IV_LEN};
 use crate::ln::msgs::{DecodeError, MAX_VALUE_MSAT};
 use crate::offers::merkle::{TaggedHash, TlvStream};
+use crate::offers::nonce::Nonce;
 use crate::offers::parse::{Bech32Encode, Bolt12ParseError, Bolt12SemanticError, ParsedMessage};
 use crate::offers::signer::{Metadata, MetadataMaterial, self};
 use crate::util::ser::{HighZeroBytesDroppedBigSize, Readable, WithoutLength, Writeable, Writer};

lightning/src/offers/refund.rs

@@ -95,10 +95,11 @@ use crate::blinded_path::BlindedPath;
 use crate::ln::types::PaymentHash;
 use crate::ln::channelmanager::PaymentId;
 use crate::ln::features::InvoiceRequestFeatures;
-use crate::ln::inbound_payment::{ExpandedKey, IV_LEN, Nonce};
+use crate::ln::inbound_payment::{ExpandedKey, IV_LEN};
 use crate::ln::msgs::{DecodeError, MAX_VALUE_MSAT};
 use crate::offers::invoice::BlindedPayInfo;
 use crate::offers::invoice_request::{InvoiceRequestTlvStream, InvoiceRequestTlvStreamRef};
+use crate::offers::nonce::Nonce;
 use crate::offers::offer::{OfferTlvStream, OfferTlvStreamRef};
 use crate::offers::parse::{Bech32Encode, Bolt12ParseError, Bolt12SemanticError, ParsedMessage};
 use crate::offers::payer::{PayerContents, PayerTlvStream, PayerTlvStreamRef};

lightning/src/offers/signer.rs

@@ -16,8 +16,9 @@ use bitcoin::hashes::sha256::Hash as Sha256;
 use bitcoin::secp256k1::{Keypair, PublicKey, Secp256k1, SecretKey, self};
 use core::fmt;
 use crate::ln::channelmanager::PaymentId;
-use crate::ln::inbound_payment::{ExpandedKey, IV_LEN, Nonce};
+use crate::ln::inbound_payment::{ExpandedKey, IV_LEN};
 use crate::offers::merkle::TlvRecord;
+use crate::offers::nonce::Nonce;
 use crate::util::ser::Writeable;
 
 use crate::prelude::*;