From: Matt Corallo <git@bluematt.me>
Date: Sat, 4 Nov 2023 20:39:03 +0000 (+0000)
Subject: Add an option to in-place decrypt with `ChaCha20Poly1305`
X-Git-Tag: v0.0.119~57^2~6
X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=commitdiff_plain;h=5e34bc4404e111d94db0ab68b9996246f5d105f9;p=rust-lightning

Add an option to in-place decrypt with `ChaCha20Poly1305`

In the next commit we'll use this to avoid an allocation when
deserializing messages from the wire.
---

diff --git a/lightning/src/util/chacha20poly1305rfc.rs b/lightning/src/util/chacha20poly1305rfc.rs
index a5bec2c82..d5792e0ac 100644
--- a/lightning/src/util/chacha20poly1305rfc.rs
+++ b/lightning/src/util/chacha20poly1305rfc.rs
@@ -122,10 +122,15 @@ mod real_chachapoly {
 			}
 		}
 
-		// Decrypt in place, without checking the tag. Use `finish_and_check_tag` to check it
-		// later when decryption finishes.
-		//
-		// Should never be `pub` because the public API should always enforce tag checking.
+		pub fn check_decrypt_in_place(&mut self, input_output: &mut [u8], tag: &[u8]) -> Result<(), ()> {
+			self.decrypt_in_place(input_output);
+			if self.finish_and_check_tag(tag) { Ok(()) } else { Err(()) }
+		}
+
+		/// Decrypt in place, without checking the tag. Use `finish_and_check_tag` to check it
+		/// later when decryption finishes.
+		///
+		/// Should never be `pub` because the public API should always enforce tag checking.
 		pub(super) fn decrypt_in_place(&mut self, input_output: &mut [u8]) {
 			debug_assert!(self.finished == false);
 			self.mac.input(input_output);
@@ -133,8 +138,8 @@ mod real_chachapoly {
 			self.cipher.process_in_place(input_output);
 		}
 
-		// If we were previously decrypting with `decrypt_in_place`, this method must be used to finish
-		// decrypting and check the tag. Returns whether or not the tag is valid.
+		/// If we were previously decrypting with `just_decrypt_in_place`, this method must be used
+		/// to check the tag. Returns whether or not the tag is valid.
 		pub(super) fn finish_and_check_tag(&mut self, tag: &[u8]) -> bool {
 			debug_assert!(self.finished == false);
 			self.finished = true;
@@ -313,6 +318,11 @@ mod fuzzy_chachapoly {
 			true
 		}
 
+		pub fn check_decrypt_in_place(&mut self, input_output: &mut [u8], tag: &[u8]) -> Result<(), ()> {
+			self.decrypt_in_place(input_output);
+			if self.finish_and_check_tag(tag) { Ok(()) } else { Err(()) }
+		}
+
 		pub(super) fn decrypt_in_place(&mut self, _input: &mut [u8]) {
 			assert!(self.finished == false);
 		}