From 4dc7e03aeb6d85dfc1eab9802604db18f08a476c Mon Sep 17 00:00:00 2001
From: Cel <181064305+Cel-Service@users.noreply.github.com>
Date: Tue, 10 Sep 2024 00:46:28 -0700
Subject: [PATCH] Add trait AeadInto so callers can provide separate input and
output buffers
---
aead/src/lib.rs | 165 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 165 insertions(+)
diff --git a/aead/src/lib.rs b/aead/src/lib.rs
index 74ea85353..bd6baed58 100644
--- a/aead/src/lib.rs
+++ b/aead/src/lib.rs
@@ -263,6 +263,89 @@ macro_rules! impl_decrypt_in_place {
}};
}
+
+/// Caller-provided input and output stateless AEAD trait.
+///
+/// This trait is both object safe and has no dependencies on `alloc` or `std`.
+pub trait AeadInto: AeadCore {
+ /// Encrypt the given plaintext, writing the ciphertext and authentication
+ /// tag into the given buffer.
+ ///
+ /// The buffer must have sufficient capacity to store the ciphertext
+ /// message, which will always be larger than the original plaintext.
+ /// The exact size needed is cipher-dependent, but generally includes
+ /// the size of an authentication tag.
+ ///
+ /// Returns an error if the buffer has insufficient capacity to store the
+ /// resulting ciphertext message.
+ ///
+ /// The default implementation assumes a postfix tag (ala AES-GCM,
+ /// AES-GCM-SIV, ChaCha20Poly1305). [`AeadInto`] implementations which do
+ /// not use a postfix tag will need to override this to correctly assemble
+ /// the ciphertext message.
+ fn encrypt_into(
+ &self,
+ nonce: &Nonce<Self>,
+ plaintext: &[u8],
+ associated_data: &[u8],
+ ciphertext: &mut [u8],
+ ) -> Result<()> {
+ if ciphertext.len() != plaintext.len().checked_add(Self::TagSize::to_usize()).ok_or(Error)? {
+ return Err(Error);
+ }
+ let (ciphertext, t) = ciphertext.split_at_mut(plaintext.len());
+ let tag = self.encrypt_into_detached(nonce, plaintext, associated_data, ciphertext)?;
+ t.copy_from_slice(tag.as_slice());
+ Ok(())
+ }
+
+ /// Encrypt the data into the given buffer, returning the authentication
+ /// tag.
+ fn encrypt_into_detached(
+ &self,
+ nonce: &Nonce<Self>,
+ plaintext: &[u8],
+ associated_data: &[u8],
+ ciphertext: &mut [u8],
+ ) -> Result<Tag<Self>>;
+
+ /// Decrypt the message into the given buffer, returning an error in the
+ /// event the provided authentication tag does not match the given
+ /// ciphertext (i.e. ciphertext is modified/unauthentic
+ ///
+ /// The default implementation assumes a postfix tag (ala AES-GCM,
+ /// AES-GCM-SIV, ChaCha20Poly1305). [`AeadInto`] implementations which do
+ /// not use a postfix tag will need to override this to correctly assemble
+ /// the ciphertext message.
+ fn decrypt_into(
+ &self,
+ nonce: &Nonce<Self>,
+ ciphertext: &[u8],
+ associated_data: &[u8],
+ plaintext: &mut [u8],
+ ) -> Result<()> {
+ if ciphertext.len() != plaintext.len().checked_add(Self::TagSize::to_usize()).ok_or(Error)? {
+ return Err(Error);
+ }
+ let (ciphertext, t) = ciphertext.split_at(plaintext.len());
+ let tag = t.try_into().map_err(|_| Error)?;
+ self.decrypt_into_detached(nonce, ciphertext, associated_data, plaintext, tag)?;
+ Ok(())
+ }
+
+ /// Decrypt the message into the given buffer, returning an error in the
+ /// event the provided authentication tag does not match the given
+ /// ciphertext (i.e. ciphertext is modified/unauthentic)
+ fn decrypt_into_detached(
+ &self,
+ nonce: &Nonce<Self>,
+ ciphertext: &[u8],
+ associated_data: &[u8],
+ plaintext: &mut [u8],
+ tag: &Tag<Self>,
+ ) -> Result<()>;
+}
+
/// In-place stateless AEAD trait.
///
/// This trait is both object safe and has no dependencies on `alloc` or `std`.
@@ -379,6 +462,88 @@ pub trait AeadMutInPlace: AeadCore {
) -> Result<()>;
}
+/// Caller-provided input and output statelful AEAD trait.
+///
+/// This trait is both object safe and has no dependencies on `alloc` or `std`.
+pub trait AeadMutInto: AeadCore {
+ /// Encrypt the given plaintext, writing the ciphertext and authentication
+ /// tag into the given buffer.
+ ///
+ /// The buffer must have sufficient capacity to store the ciphertext
+ /// message, which will always be larger than the original plaintext.
+ /// The exact size needed is cipher-dependent, but generally includes
+ /// the size of an authentication tag.
+ ///
+ /// Returns an error if the buffer has insufficient capacity to store the
+ /// resulting ciphertext message.
+ ///
+ /// The default implementation assumes a postfix tag (ala AES-GCM,
+ /// AES-GCM-SIV, ChaCha20Poly1305). [`AeadMutInto`] implementations which
+ /// do not use a postfix tag will need to override this to correctly
+ /// assemble the ciphertext message.
+ fn encrypt_into(
+ &mut self,
+ nonce: &Nonce<Self>,
+ plaintext: &[u8],
+ associated_data: &[u8],
+ ciphertext: &mut [u8],
+ ) -> Result<()> {
+ if ciphertext.len() != plaintext.len().checked_add(Self::TagSize::to_usize()).ok_or(Error)? {
+ return Err(Error);
+ }
+ let (ciphertext, t) = ciphertext.split_at_mut(plaintext.len());
+ let tag = self.encrypt_into_detached(nonce, plaintext, associated_data, ciphertext)?;
+ t.copy_from_slice(tag.as_slice());
+ Ok(())
+ }
+
+ /// Encrypt the data into the given buffer, returning the authentication
+ /// tag
+ fn encrypt_into_detached(
+ &mut self,
+ nonce: &Nonce<Self>,
+ plaintext: &[u8],
+ associated_data: &[u8],
+ ciphertext: &mut [u8],
+ ) -> Result<Tag<Self>>;
+
+ /// Decrypt the message into the given buffer, returning an error in the
+ /// event the provided authentication tag does not match the given
+ /// ciphertext (i.e. ciphertext is modified/unauthentic
+ ///
+ /// The default implementation assumes a postfix tag (ala AES-GCM,
+ /// AES-GCM-SIV, ChaCha20Poly1305). [`AeadMutInto`] implementations which
+ /// do not use a postfix tag will need to override this to correctly
+ /// assemble the ciphertext message.
+ fn decrypt_into(
+ &mut self,
+ nonce: &Nonce<Self>,
+ ciphertext: &[u8],
+ associated_data: &[u8],
+ plaintext: &mut [u8],
+ ) -> Result<()> {
+ if ciphertext.len() != plaintext.len().checked_add(Self::TagSize::to_usize()).ok_or(Error)? {
+ return Err(Error);
+ }
+ let (ciphertext, t) = ciphertext.split_at(plaintext.len());
+ let tag = t.try_into().map_err(|_| Error)?;
+ self.decrypt_into_detached(nonce, ciphertext, associated_data, plaintext, tag)?;
+ Ok(())
+ }
+
+ /// Decrypt the message into the given buffer, returning an error in the
+ /// event the provided authentication tag does not match the given
+ /// ciphertext (i.e. ciphertext is modified/unauthentic)
+ fn decrypt_into_detached(
+ &mut self,
+ nonce: &Nonce<Self>,
+ ciphertext: &[u8],
+ associated_data: &[u8],
+ plaintext: &mut [u8],
+ tag: &Tag<Self>,
+ ) -> Result<()>;
+}
+
#[cfg(feature = "alloc")]
impl<Alg: AeadInPlace> Aead for Alg {
fn encrypt<'msg, 'aad>(