feat: use v2 SEIPD when sending messages to self

Author: link2xt

src/e2ee.rs

@@ -8,7 +8,7 @@ use mail_builder::mime::MimePart;
 use crate::aheader::{Aheader, EncryptPreference};
 use crate::context::Context;
 use crate::key::{SignedPublicKey, load_self_public_key, load_self_secret_key};
-use crate::pgp;
+use crate::pgp::{self, SeipdVersion};
 
 #[derive(Debug)]
 pub struct EncryptHelper {
@@ -47,6 +47,7 @@ impl EncryptHelper {
  mail_to_encrypt: MimePart<'static>,
  compress: bool,
  anonymous_recipients: bool,
+ seipd_version: SeipdVersion,
  ) -> Result<String> {
  let sign_key = load_self_secret_key(context).await?;
 
@@ -60,6 +61,7 @@ impl EncryptHelper {
  sign_key,
  compress,
  anonymous_recipients,
+ seipd_version,
  )
  .await?;
 

src/mimefactory.rs

@@ -32,6 +32,7 @@ use crate::message::{Message, MsgId, Viewtype};
 use crate::mimeparser::{SystemMessage, is_hidden};
 use crate::param::Param;
 use crate::peer_channels::{create_iroh_header, get_iroh_topic_for_msg};
+use crate::pgp::SeipdVersion;
 use crate::simplify::escape_message_footer_marks;
 use crate::stock_str;
 use crate::tools::{
@@ -1258,6 +1259,17 @@ impl MimeFactory {
  } else {
  // Asymmetric encryption
 
+ let seipd_version = if encryption_pubkeys.is_empty() {
+ // If message is sent only to self,
+ // use v2 SEIPD.
+ SeipdVersion::V2
+ } else {
+ // If message is sent to others,
+ // they may not support v2 SEIPD yet,
+ // so use v1 SEIPD.
+ SeipdVersion::V1
+ };
+
  // Encrypt to self unconditionally,
  // even for a single-device setup.
  let mut encryption_keyring = vec![encrypt_helper.public_key.clone()];
@@ -1271,6 +1283,7 @@ impl MimeFactory {
  message,
  compress,
  anonymous_recipients,
+ seipd_version,
  )
  .await?
  };

src/pgp.rs

@@ -160,6 +160,20 @@ fn select_pk_for_encryption(key: &SignedPublicKey) -> Option<&SignedPublicSubKey
  .find(|subkey| subkey.is_encryption_key())
 }
 
+/// Version of SEIPD packet to use.
+///
+/// See
+/// <https://www.rfc-editor.org/rfc/rfc9580#name-avoiding-ciphertext-malleab>
+/// for the discussion on when v2 SEIPD should be used.
+#[derive(Debug)]
+pub enum SeipdVersion {
+ /// Use v1 SEIPD, for compatibility.
+ V1,
+
+ /// Use v2 SEIPD when we know that v2 SEIPD is supported.
+ V2,
+}
+
 /// Encrypts `plain` text using `public_keys_for_encryption`
 /// and signs it using `private_key_for_signing`.
 pub async fn pk_encrypt(
@@ -168,31 +182,63 @@ pub async fn pk_encrypt(
  private_key_for_signing: SignedSecretKey,
  compress: bool,
  anonymous_recipients: bool,
+ seipd_version: SeipdVersion,
 ) -> Result<String> {
  Handle::current()
  .spawn_blocking(move || {
  let mut rng = thread_rng();
 
- let pkeys = public_keys_for_encryption
- .iter()
- .filter_map(select_pk_for_encryption);
-
  let msg = MessageBuilder::from_bytes("", plain);
- let mut msg = msg.seipd_v1(&mut rng, SYMMETRIC_KEY_ALGORITHM);
- for pkey in pkeys {
- if anonymous_recipients {
- msg.encrypt_to_key_anonymous(&mut rng, &pkey)?;
- } else {
- msg.encrypt_to_key(&mut rng, &pkey)?;
- }
- }
 
- msg.sign(&*private_key_for_signing, Password::empty(), HASH_ALGORITHM);
- if compress {
- msg.compression(CompressionAlgorithm::ZLIB);
- }
-
- let encoded_msg = msg.to_armored_string(&mut rng, Default::default())?;
+ let encoded_msg = match seipd_version {
+ SeipdVersion::V1 => {
+ let mut msg = msg.seipd_v1(&mut rng, SYMMETRIC_KEY_ALGORITHM);
+ let pkeys = public_keys_for_encryption
+ .iter()
+ .filter_map(select_pk_for_encryption);
+
+ for pkey in pkeys {
+ if anonymous_recipients {
+ msg.encrypt_to_key_anonymous(&mut rng, &pkey)?;
+ } else {
+ msg.encrypt_to_key(&mut rng, &pkey)?;
+ }
+ }
+
+ msg.sign(&*private_key_for_signing, Password::empty(), HASH_ALGORITHM);
+ if compress {
+ msg.compression(CompressionAlgorithm::ZLIB);
+ }
+
+ msg.to_armored_string(&mut rng, Default::default())?
+ }
+ SeipdVersion::V2 => {
+ let mut msg = msg.seipd_v2(
+ &mut rng,
+ SYMMETRIC_KEY_ALGORITHM,
+ AeadAlgorithm::Ocb,
+ ChunkSize::C8KiB,
+ );
+ let pkeys = public_keys_for_encryption
+ .iter()
+ .filter_map(select_pk_for_encryption);
+
+ for pkey in pkeys {
+ if anonymous_recipients {
+ msg.encrypt_to_key_anonymous(&mut rng, &pkey)?;
+ } else {
+ msg.encrypt_to_key(&mut rng, &pkey)?;
+ }
+ }
+
+ msg.sign(&*private_key_for_signing, Password::empty(), HASH_ALGORITHM);
+ if compress {
+ msg.compression(CompressionAlgorithm::ZLIB);
+ }
+
+ msg.to_armored_string(&mut rng, Default::default())?
+ }
+ };
 
  Ok(encoded_msg)
  })
@@ -547,6 +593,7 @@ mod tests {
  KEYS.alice_secret.clone(),
  compress,
  anonymous_recipients,
+ SeipdVersion::V2,
  )
  .await
  .unwrap()
@@ -716,6 +763,7 @@ mod tests {
  KEYS.alice_secret.clone(),
  true,
  true,
+ SeipdVersion::V2,
  )
  .await?;