Factor decrypt module out of e2ee module

CHANGELOG.md

@@ -17,6 +17,7 @@
 - added a JSON RPC API, accessible through a WebSocket server, the CFFI bindings and the Node.js bindings #3463
 
 ### Changes
+- refactorings #3545
 
 ### Fixes
 - improved error handling for account setup from qrcode #3474

src/decrypt.rs

@@ -0,0 +1,376 @@
+//! End-to-end decryption support.
+
+use std::collections::HashSet;
+
+use anyhow::{Context as _, Result};
+use mailparse::ParsedMail;
+
+use crate::aheader::Aheader;
+use crate::contact::addr_cmp;
+use crate::context::Context;
+use crate::headerdef::HeaderDef;
+use crate::headerdef::HeaderDefMap;
+use crate::key::{DcKey, Fingerprint, SignedPublicKey, SignedSecretKey};
+use crate::keyring::Keyring;
+use crate::log::LogExt;
+use crate::peerstate::Peerstate;
+use crate::pgp;
+
+/// Tries to decrypt a message, but only if it is structured as an
+/// Autocrypt message.
+///
+/// Returns decrypted body and a set of valid signature fingerprints
+/// if successful.
+///
+/// If the message is wrongly signed, this will still return the decrypted
+/// message but the HashSet will be empty.
+pub async fn try_decrypt(
+    context: &Context,
+    mail: &ParsedMail<'_>,
+    decryption_info: &DecryptionInfo,
+) -> Result<Option<(Vec<u8>, HashSet<Fingerprint>)>> {
+    // Possibly perform decryption
+    let public_keyring_for_validate = keyring_from_peerstate(&decryption_info.peerstate);
+
+    let context = context;
+    let encrypted_data_part = match get_autocrypt_mime(mail)
+        .or_else(|| get_mixed_up_mime(mail))
+        .or_else(|| get_attachment_mime(mail))
+    {
+        None => {
+            // not an autocrypt mime message, abort and ignore
+            return Ok(None);
+        }
+        Some(res) => res,
+    };
+    info!(context, "Detected Autocrypt-mime message");
+    let private_keyring: Keyring<SignedSecretKey> = Keyring::new_self(context)
+        .await
+        .context("failed to get own keyring")?;
+
+    decrypt_part(
+        encrypted_data_part,
+        private_keyring,
+        public_keyring_for_validate,
+    )
+    .await
+}
+
+pub async fn create_decryption_info(
+    context: &Context,
+    mail: &ParsedMail<'_>,
+    message_time: i64,
+) -> Result<DecryptionInfo> {
+    let from = mail
+        .headers
+        .get_header(HeaderDef::From_)
+        .and_then(|from_addr| mailparse::addrparse_header(from_addr).ok())
+        .and_then(|from| from.extract_single_info())
+        .map(|from| from.addr)
+        .unwrap_or_default();
+
+    let autocrypt_header = Aheader::from_headers(&from, &mail.headers)
+        .ok_or_log_msg(context, "Failed to parse Autocrypt header")
+        .flatten();
+
+    let peerstate =
+        get_autocrypt_peerstate(context, &from, autocrypt_header.as_ref(), message_time).await?;
+
+    Ok(DecryptionInfo {
+        from,
+        autocrypt_header,
+        peerstate,
+        message_time,
+    })
+}
+
+#[derive(Debug)]
+pub struct DecryptionInfo {
+    /// The From address. This is the address from the unnencrypted, outer
+    /// From header.
+    pub from: String,
+    pub autocrypt_header: Option<Aheader>,
+    /// The peerstate that will be used to validate the signatures
+    pub peerstate: Option<Peerstate>,
+    /// The timestamp when the message was sent.
+    /// If this is older than the peerstate's last_seen, this probably
+    /// means out-of-order message arrival, We don't modify the
+    /// peerstate in this case.
+    pub message_time: i64,
+}
+
+/// Returns a reference to the encrypted payload of a ["Mixed
+/// Up"][pgpmime-message-mangling] message.
+///
+/// According to [RFC 3156] encrypted messages should have
+/// `multipart/encrypted` MIME type and two parts, but Microsoft
+/// Exchange and ProtonMail IMAP/SMTP Bridge are known to mangle this
+/// structure by changing the type to `multipart/mixed` and prepending
+/// an empty part at the start.
+///
+/// ProtonMail IMAP/SMTP Bridge prepends a part literally saying
+/// "Empty Message", so we don't check its contents at all, checking
+/// only for `text/plain` type.
+///
+/// Returns `None` if the message is not a "Mixed Up" message.
+///
+/// [RFC 3156]: https://www.rfc-editor.org/info/rfc3156
+/// [pgpmime-message-mangling]: https://tools.ietf.org/id/draft-dkg-openpgp-pgpmime-message-mangling-00.html
+fn get_mixed_up_mime<'a, 'b>(mail: &'a ParsedMail<'b>) -> Option<&'a ParsedMail<'b>> {
+    if mail.ctype.mimetype != "multipart/mixed" {
+        return None;
+    }
+    if let [first_part, second_part, third_part] = &mail.subparts[..] {
+        if first_part.ctype.mimetype == "text/plain"
+            && second_part.ctype.mimetype == "application/pgp-encrypted"
+            && third_part.ctype.mimetype == "application/octet-stream"
+        {
+            Some(third_part)
+        } else {
+            None
+        }
+    } else {
+        None
+    }
+}
+
+/// Returns a reference to the encrypted payload of a message turned into attachment.
+///
+/// Google Workspace has an option "Append footer" which appends standard footer defined
+/// by administrator to all outgoing messages. However, there is no plain text part in
+/// encrypted messages sent by Delta Chat, so Google Workspace turns the message into
+/// multipart/mixed MIME, where the first part is an empty plaintext part with a footer
+/// and the second part is the original encrypted message.
+fn get_attachment_mime<'a, 'b>(mail: &'a ParsedMail<'b>) -> Option<&'a ParsedMail<'b>> {
+    if mail.ctype.mimetype != "multipart/mixed" {
+        return None;
+    }
+    if let [first_part, second_part] = &mail.subparts[..] {
+        if first_part.ctype.mimetype == "text/plain"
+            && second_part.ctype.mimetype == "multipart/encrypted"
+        {
+            get_autocrypt_mime(second_part)
+        } else {
+            None
+        }
+    } else {
+        None
+    }
+}
+
+/// Returns a reference to the encrypted payload of a valid PGP/MIME message.
+///
+/// Returns `None` if the message is not a valid PGP/MIME message.
+fn get_autocrypt_mime<'a, 'b>(mail: &'a ParsedMail<'b>) -> Option<&'a ParsedMail<'b>> {
+    if mail.ctype.mimetype != "multipart/encrypted" {
+        return None;
+    }
+    if let [first_part, second_part] = &mail.subparts[..] {
+        if first_part.ctype.mimetype == "application/pgp-encrypted"
+            && second_part.ctype.mimetype == "application/octet-stream"
+        {
+            Some(second_part)
+        } else {
+            None
+        }
+    } else {
+        None
+    }
+}
+
+/// Returns Ok(None) if nothing encrypted was found.
+async fn decrypt_part(
+    mail: &ParsedMail<'_>,
+    private_keyring: Keyring<SignedSecretKey>,
+    public_keyring_for_validate: Keyring<SignedPublicKey>,
+) -> Result<Option<(Vec<u8>, HashSet<Fingerprint>)>> {
+    let data = mail.get_body_raw()?;
+
+    if has_decrypted_pgp_armor(&data) {
+        let (plain, ret_valid_signatures) =
+            pgp::pk_decrypt(data, private_keyring, &public_keyring_for_validate).await?;
+
+        // Check for detached signatures.
+        // If decrypted part is a multipart/signed, then there is a detached signature.
+        let decrypted_part = mailparse::parse_mail(&plain)?;
+        if let Some((content, valid_detached_signatures)) =
+            validate_detached_signature(&decrypted_part, &public_keyring_for_validate)?
+        {
+            return Ok(Some((content, valid_detached_signatures)));
+        } else {
+            // If the message was wrongly or not signed, still return the plain text.
+            // The caller has to check if the signatures set is empty then.
+
+            return Ok(Some((plain, ret_valid_signatures)));
+        }
+    }
+
+    Ok(None)
+}
+
+#[allow(clippy::indexing_slicing)]
+fn has_decrypted_pgp_armor(input: &[u8]) -> bool {
+    if let Some(index) = input.iter().position(|b| *b > b' ') {
+        if input.len() - index > 26 {
+            let start = index;
+            let end = start + 27;
+
+            return &input[start..end] == b"-----BEGIN PGP MESSAGE-----";
+        }
+    }
+
+    false
+}
+
+/// Validates signatures of Multipart/Signed message part, as defined in RFC 1847.
+///
+/// Returns `None` if the part is not a Multipart/Signed part, otherwise retruns the set of key
+/// fingerprints for which there is a valid signature.
+fn validate_detached_signature(
+    mail: &ParsedMail<'_>,
+    public_keyring_for_validate: &Keyring<SignedPublicKey>,
+) -> Result<Option<(Vec<u8>, HashSet<Fingerprint>)>> {
+    if mail.ctype.mimetype != "multipart/signed" {
+        return Ok(None);
+    }
+
+    if let [first_part, second_part] = &mail.subparts[..] {
+        // First part is the content, second part is the signature.
+        let content = first_part.raw_bytes;
+        let signature = second_part.get_body_raw()?;
+        let ret_valid_signatures =
+            pgp::pk_validate(content, &signature, public_keyring_for_validate)?;
+
+        Ok(Some((content.to_vec(), ret_valid_signatures)))
+    } else {
+        Ok(None)
+    }
+}
+
+fn keyring_from_peerstate(peerstate: &Option<Peerstate>) -> Keyring<SignedPublicKey> {
+    let mut public_keyring_for_validate: Keyring<SignedPublicKey> = Keyring::new();
+    if let Some(ref peerstate) = *peerstate {
+        if let Some(key) = &peerstate.public_key {
+            public_keyring_for_validate.add(key.clone());
+        } else if let Some(key) = &peerstate.gossip_key {
+            public_keyring_for_validate.add(key.clone());
+        }
+    }
+    public_keyring_for_validate
+}
+
+/// Applies Autocrypt header to Autocrypt peer state and saves it into the database.
+///
+/// If we already know this fingerprint from another contact's peerstate, return that
+/// peerstate in order to make AEAP work, but don't save it into the db yet.
+///
+/// Returns updated peerstate.
+pub(crate) async fn get_autocrypt_peerstate(
+    context: &Context,
+    from: &str,
+    autocrypt_header: Option<&Aheader>,
+    message_time: i64,
+) -> Result<Option<Peerstate>> {
+    let mut peerstate;
+
+    // Apply Autocrypt header
+    if let Some(header) = autocrypt_header {
+        // The "from_verified_fingerprint" part is for AEAP:
+        // If we know this fingerprint from another addr,
+        // we may want to do a transition from this other addr
+        // (and keep its peerstate)
+        // For security reasons, for now, we only do a transition
+        // if the fingerprint is verified.
+        peerstate = Peerstate::from_verified_fingerprint_or_addr(
+            context,
+            &header.public_key.fingerprint(),
+            from,
+        )
+        .await?;
+
+        if let Some(ref mut peerstate) = peerstate {
+            if addr_cmp(&peerstate.addr, from) {
+                peerstate.apply_header(header, message_time);
+                peerstate.save_to_db(&context.sql, false).await?;
+            }
+            // If `peerstate.addr` and `from` differ, this means that
+            // someone is using the same key but a different addr, probably
+            // because they made an AEAP transition.
+            // But we don't know if that's legit until we checked the
+            // signatures, so wait until then with writing anything
+            // to the database.
+        } else {
+            let p = Peerstate::from_header(header, message_time);
+            p.save_to_db(&context.sql, true).await?;
+            peerstate = Some(p);
+        }
+    } else {
+        peerstate = Peerstate::from_addr(context, from).await?;
+    }
+
+    Ok(peerstate)
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::receive_imf::receive_imf;
+    use crate::test_utils::TestContext;
+
+    use super::*;
+
+    #[test]
+    fn test_has_decrypted_pgp_armor() {
+        let data = b" -----BEGIN PGP MESSAGE-----";
+        assert_eq!(has_decrypted_pgp_armor(data), true);
+
+        let data = b"    \n-----BEGIN PGP MESSAGE-----";
+        assert_eq!(has_decrypted_pgp_armor(data), true);
+
+        let data = b"    -----BEGIN PGP MESSAGE---";
+        assert_eq!(has_decrypted_pgp_armor(data), false);
+
+        let data = b" -----BEGIN PGP MESSAGE-----";
+        assert_eq!(has_decrypted_pgp_armor(data), true);
+
+        let data = b"blas";
+        assert_eq!(has_decrypted_pgp_armor(data), false);
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+    async fn test_mixed_up_mime() -> Result<()> {
+        // "Mixed Up" mail as received when sending an encrypted
+        // message using Delta Chat Desktop via ProtonMail IMAP/SMTP
+        // Bridge.
+        let mixed_up_mime = include_bytes!("../test-data/message/protonmail-mixed-up.eml");
+        let mail = mailparse::parse_mail(mixed_up_mime)?;
+        assert!(get_autocrypt_mime(&mail).is_none());
+        assert!(get_mixed_up_mime(&mail).is_some());
+        assert!(get_attachment_mime(&mail).is_none());
+
+        // Same "Mixed Up" mail repaired by Thunderbird 78.9.0.
+        //
+        // It added `X-Enigmail-Info: Fixed broken PGP/MIME message`
+        // header although the repairing is done by the built-in
+        // OpenPGP support, not Enigmail.
+        let repaired_mime = include_bytes!("../test-data/message/protonmail-repaired.eml");
+        let mail = mailparse::parse_mail(repaired_mime)?;
+        assert!(get_autocrypt_mime(&mail).is_some());
+        assert!(get_mixed_up_mime(&mail).is_none());
+        assert!(get_attachment_mime(&mail).is_none());
+
+        // Another form of "Mixed Up" mail created by Google Workspace,
+        // where original message is turned into attachment to empty plaintext message.
+        let attachment_mime = include_bytes!("../test-data/message/google-workspace-mixed-up.eml");
+        let mail = mailparse::parse_mail(attachment_mime)?;
+        assert!(get_autocrypt_mime(&mail).is_none());
+        assert!(get_mixed_up_mime(&mail).is_none());
+        assert!(get_attachment_mime(&mail).is_some());
+
+        let bob = TestContext::new_bob().await;
+        receive_imf(&bob, attachment_mime, false).await?;
+        let msg = bob.get_last_msg().await;
+        assert_eq!(msg.text.as_deref(), Some("Hello from Thunderbird!"));
+
+        Ok(())
+    }
+}

src/e2ee.rs

@@ -1,20 +1,13 @@
 //! End-to-end encryption support.
 
-use std::collections::HashSet;
-
 use anyhow::{format_err, Context as _, Result};
-use mailparse::ParsedMail;
 use num_traits::FromPrimitive;
 
 use crate::aheader::{Aheader, EncryptPreference};
 use crate::config::Config;
-use crate::contact::addr_cmp;
 use crate::context::Context;
-use crate::headerdef::HeaderDef;
+use crate::key::{DcKey, SignedPublicKey, SignedSecretKey};
-use crate::headerdef::HeaderDefMap;
-use crate::key::{DcKey, Fingerprint, SignedPublicKey, SignedSecretKey};
 use crate::keyring::Keyring;
-use crate::log::LogExt;
 use crate::peerstate::{Peerstate, PeerstateVerifiedStatus};
 use crate::pgp;
 
@@ -133,301 +126,6 @@ impl EncryptHelper {
     }
 }
 
-/// Applies Autocrypt header to Autocrypt peer state and saves it into the database.
-///
-/// If we already know this fingerprint from another contact's peerstate, return that
-/// peerstate in order to make AEAP work, but don't save it into the db yet.
-///
-/// Returns updated peerstate.
-pub(crate) async fn get_autocrypt_peerstate(
-    context: &Context,
-    from: &str,
-    autocrypt_header: Option<&Aheader>,
-    message_time: i64,
-) -> Result<Option<Peerstate>> {
-    let mut peerstate;
-
-    // Apply Autocrypt header
-    if let Some(header) = autocrypt_header {
-        // The "from_verified_fingerprint" part is for AEAP:
-        // If we know this fingerprint from another addr,
-        // we may want to do a transition from this other addr
-        // (and keep its peerstate)
-        // For security reasons, for now, we only do a transition
-        // if the fingerprint is verified.
-        peerstate = Peerstate::from_verified_fingerprint_or_addr(
-            context,
-            &header.public_key.fingerprint(),
-            from,
-        )
-        .await?;
-
-        if let Some(ref mut peerstate) = peerstate {
-            if addr_cmp(&peerstate.addr, from) {
-                peerstate.apply_header(header, message_time);
-                peerstate.save_to_db(&context.sql, false).await?;
-            }
-            // If `peerstate.addr` and `from` differ, this means that
-            // someone is using the same key but a different addr, probably
-            // because they made an AEAP transition.
-            // But we don't know if that's legit until we checked the
-            // signatures, so wait until then with writing anything
-            // to the database.
-        } else {
-            let p = Peerstate::from_header(header, message_time);
-            p.save_to_db(&context.sql, true).await?;
-            peerstate = Some(p);
-        }
-    } else {
-        peerstate = Peerstate::from_addr(context, from).await?;
-    }
-
-    Ok(peerstate)
-}
-
-/// Tries to decrypt a message, but only if it is structured as an
-/// Autocrypt message.
-///
-/// Returns decrypted body and a set of valid signature fingerprints
-/// if successful.
-///
-/// If the message is wrongly signed, this will still return the decrypted
-/// message but the HashSet will be empty.
-pub async fn try_decrypt(
-    context: &Context,
-    mail: &ParsedMail<'_>,
-    decryption_info: &DecryptionInfo,
-) -> Result<Option<(Vec<u8>, HashSet<Fingerprint>)>> {
-    // Possibly perform decryption
-    let public_keyring_for_validate = keyring_from_peerstate(&decryption_info.peerstate);
-
-    let context = context;
-    let encrypted_data_part = match get_autocrypt_mime(mail)
-        .or_else(|| get_mixed_up_mime(mail))
-        .or_else(|| get_attachment_mime(mail))
-    {
-        None => {
-            // not an autocrypt mime message, abort and ignore
-            return Ok(None);
-        }
-        Some(res) => res,
-    };
-    info!(context, "Detected Autocrypt-mime message");
-    let private_keyring: Keyring<SignedSecretKey> = Keyring::new_self(context)
-        .await
-        .context("failed to get own keyring")?;
-
-    decrypt_part(
-        encrypted_data_part,
-        private_keyring,
-        public_keyring_for_validate,
-    )
-    .await
-}
-
-pub async fn create_decryption_info(
-    context: &Context,
-    mail: &ParsedMail<'_>,
-    message_time: i64,
-) -> Result<DecryptionInfo> {
-    let from = mail
-        .headers
-        .get_header(HeaderDef::From_)
-        .and_then(|from_addr| mailparse::addrparse_header(from_addr).ok())
-        .and_then(|from| from.extract_single_info())
-        .map(|from| from.addr)
-        .unwrap_or_default();
-
-    let autocrypt_header = Aheader::from_headers(&from, &mail.headers)
-        .ok_or_log_msg(context, "Failed to parse Autocrypt header")
-        .flatten();
-
-    let peerstate =
-        get_autocrypt_peerstate(context, &from, autocrypt_header.as_ref(), message_time).await?;
-
-    Ok(DecryptionInfo {
-        from,
-        autocrypt_header,
-        peerstate,
-        message_time,
-    })
-}
-
-#[derive(Debug)]
-pub struct DecryptionInfo {
-    /// The From address. This is the address from the unnencrypted, outer
-    /// From header.
-    pub from: String,
-    pub autocrypt_header: Option<Aheader>,
-    /// The peerstate that will be used to validate the signatures
-    pub peerstate: Option<Peerstate>,
-    /// The timestamp when the message was sent.
-    /// If this is older than the peerstate's last_seen, this probably
-    /// means out-of-order message arrival, We don't modify the
-    /// peerstate in this case.
-    pub message_time: i64,
-}
-
-/// Returns a reference to the encrypted payload of a valid PGP/MIME message.
-///
-/// Returns `None` if the message is not a valid PGP/MIME message.
-fn get_autocrypt_mime<'a, 'b>(mail: &'a ParsedMail<'b>) -> Option<&'a ParsedMail<'b>> {
-    if mail.ctype.mimetype != "multipart/encrypted" {
-        return None;
-    }
-    if let [first_part, second_part] = &mail.subparts[..] {
-        if first_part.ctype.mimetype == "application/pgp-encrypted"
-            && second_part.ctype.mimetype == "application/octet-stream"
-        {
-            Some(second_part)
-        } else {
-            None
-        }
-    } else {
-        None
-    }
-}
-
-/// Returns a reference to the encrypted payload of a ["Mixed
-/// Up"][pgpmime-message-mangling] message.
-///
-/// According to [RFC 3156] encrypted messages should have
-/// `multipart/encrypted` MIME type and two parts, but Microsoft
-/// Exchange and ProtonMail IMAP/SMTP Bridge are known to mangle this
-/// structure by changing the type to `multipart/mixed` and prepending
-/// an empty part at the start.
-///
-/// ProtonMail IMAP/SMTP Bridge prepends a part literally saying
-/// "Empty Message", so we don't check its contents at all, checking
-/// only for `text/plain` type.
-///
-/// Returns `None` if the message is not a "Mixed Up" message.
-///
-/// [RFC 3156]: https://www.rfc-editor.org/info/rfc3156
-/// [pgpmime-message-mangling]: https://tools.ietf.org/id/draft-dkg-openpgp-pgpmime-message-mangling-00.html
-fn get_mixed_up_mime<'a, 'b>(mail: &'a ParsedMail<'b>) -> Option<&'a ParsedMail<'b>> {
-    if mail.ctype.mimetype != "multipart/mixed" {
-        return None;
-    }
-    if let [first_part, second_part, third_part] = &mail.subparts[..] {
-        if first_part.ctype.mimetype == "text/plain"
-            && second_part.ctype.mimetype == "application/pgp-encrypted"
-            && third_part.ctype.mimetype == "application/octet-stream"
-        {
-            Some(third_part)
-        } else {
-            None
-        }
-    } else {
-        None
-    }
-}
-
-/// Returns a reference to the encrypted payload of a message turned into attachment.
-///
-/// Google Workspace has an option "Append footer" which appends standard footer defined
-/// by administrator to all outgoing messages. However, there is no plain text part in
-/// encrypted messages sent by Delta Chat, so Google Workspace turns the message into
-/// multipart/mixed MIME, where the first part is an empty plaintext part with a footer
-/// and the second part is the original encrypted message.
-fn get_attachment_mime<'a, 'b>(mail: &'a ParsedMail<'b>) -> Option<&'a ParsedMail<'b>> {
-    if mail.ctype.mimetype != "multipart/mixed" {
-        return None;
-    }
-    if let [first_part, second_part] = &mail.subparts[..] {
-        if first_part.ctype.mimetype == "text/plain"
-            && second_part.ctype.mimetype == "multipart/encrypted"
-        {
-            get_autocrypt_mime(second_part)
-        } else {
-            None
-        }
-    } else {
-        None
-    }
-}
-
-fn keyring_from_peerstate(peerstate: &Option<Peerstate>) -> Keyring<SignedPublicKey> {
-    let mut public_keyring_for_validate: Keyring<SignedPublicKey> = Keyring::new();
-    if let Some(ref peerstate) = *peerstate {
-        if let Some(key) = &peerstate.public_key {
-            public_keyring_for_validate.add(key.clone());
-        } else if let Some(key) = &peerstate.gossip_key {
-            public_keyring_for_validate.add(key.clone());
-        }
-    }
-    public_keyring_for_validate
-}
-
-/// Validates signatures of Multipart/Signed message part, as defined in RFC 1847.
-///
-/// Returns `None` if the part is not a Multipart/Signed part, otherwise retruns the set of key
-/// fingerprints for which there is a valid signature.
-fn validate_detached_signature(
-    mail: &ParsedMail<'_>,
-    public_keyring_for_validate: &Keyring<SignedPublicKey>,
-) -> Result<Option<(Vec<u8>, HashSet<Fingerprint>)>> {
-    if mail.ctype.mimetype != "multipart/signed" {
-        return Ok(None);
-    }
-
-    if let [first_part, second_part] = &mail.subparts[..] {
-        // First part is the content, second part is the signature.
-        let content = first_part.raw_bytes;
-        let signature = second_part.get_body_raw()?;
-        let ret_valid_signatures =
-            pgp::pk_validate(content, &signature, public_keyring_for_validate)?;
-
-        Ok(Some((content.to_vec(), ret_valid_signatures)))
-    } else {
-        Ok(None)
-    }
-}
-
-/// Returns Ok(None) if nothing encrypted was found.
-async fn decrypt_part(
-    mail: &ParsedMail<'_>,
-    private_keyring: Keyring<SignedSecretKey>,
-    public_keyring_for_validate: Keyring<SignedPublicKey>,
-) -> Result<Option<(Vec<u8>, HashSet<Fingerprint>)>> {
-    let data = mail.get_body_raw()?;
-
-    if has_decrypted_pgp_armor(&data) {
-        let (plain, ret_valid_signatures) =
-            pgp::pk_decrypt(data, private_keyring, &public_keyring_for_validate).await?;
-
-        // Check for detached signatures.
-        // If decrypted part is a multipart/signed, then there is a detached signature.
-        let decrypted_part = mailparse::parse_mail(&plain)?;
-        if let Some((content, valid_detached_signatures)) =
-            validate_detached_signature(&decrypted_part, &public_keyring_for_validate)?
-        {
-            return Ok(Some((content, valid_detached_signatures)));
-        } else {
-            // If the message was wrongly or not signed, still return the plain text.
-            // The caller has to check if the signatures set is empty then.
-
-            return Ok(Some((plain, ret_valid_signatures)));
-        }
-    }
-
-    Ok(None)
-}
-
-#[allow(clippy::indexing_slicing)]
-fn has_decrypted_pgp_armor(input: &[u8]) -> bool {
-    if let Some(index) = input.iter().position(|b| *b > b' ') {
-        if input.len() - index > 26 {
-            let start = index;
-            let end = start + 27;
-
-            return &input[start..end] == b"-----BEGIN PGP MESSAGE-----";
-        }
-    }
-
-    false
-}
-
 /// Ensures a private key exists for the configured user.
 ///
 /// Normally the private key is generated when the first message is
@@ -450,7 +148,6 @@ mod tests {
     use crate::message::{Message, Viewtype};
     use crate::param::Param;
     use crate::peerstate::ToSave;
-    use crate::receive_imf::receive_imf;
     use crate::test_utils::{bob_keypair, TestContext};
 
     use super::*;
@@ -498,24 +195,6 @@ Sent with my Delta Chat Messenger: https://delta.chat";
         );
     }
 
-    #[test]
-    fn test_has_decrypted_pgp_armor() {
-        let data = b" -----BEGIN PGP MESSAGE-----";
-        assert_eq!(has_decrypted_pgp_armor(data), true);
-
-        let data = b"    \n-----BEGIN PGP MESSAGE-----";
-        assert_eq!(has_decrypted_pgp_armor(data), true);
-
-        let data = b"    -----BEGIN PGP MESSAGE---";
-        assert_eq!(has_decrypted_pgp_armor(data), false);
-
-        let data = b" -----BEGIN PGP MESSAGE-----";
-        assert_eq!(has_decrypted_pgp_armor(data), true);
-
-        let data = b"blas";
-        assert_eq!(has_decrypted_pgp_armor(data), false);
-    }
-
     #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
     async fn test_encrypted_no_autocrypt() -> anyhow::Result<()> {
         let alice = TestContext::new_alice().await;
@@ -650,42 +329,4 @@ Sent with my Delta Chat Messenger: https://delta.chat";
         assert!(encrypt_helper.should_encrypt(&t, true, &ps).is_err());
         assert!(!encrypt_helper.should_encrypt(&t, false, &ps).unwrap());
     }
-
-    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
-    async fn test_mixed_up_mime() -> Result<()> {
-        // "Mixed Up" mail as received when sending an encrypted
-        // message using Delta Chat Desktop via ProtonMail IMAP/SMTP
-        // Bridge.
-        let mixed_up_mime = include_bytes!("../test-data/message/protonmail-mixed-up.eml");
-        let mail = mailparse::parse_mail(mixed_up_mime)?;
-        assert!(get_autocrypt_mime(&mail).is_none());
-        assert!(get_mixed_up_mime(&mail).is_some());
-        assert!(get_attachment_mime(&mail).is_none());
-
-        // Same "Mixed Up" mail repaired by Thunderbird 78.9.0.
-        //
-        // It added `X-Enigmail-Info: Fixed broken PGP/MIME message`
-        // header although the repairing is done by the built-in
-        // OpenPGP support, not Enigmail.
-        let repaired_mime = include_bytes!("../test-data/message/protonmail-repaired.eml");
-        let mail = mailparse::parse_mail(repaired_mime)?;
-        assert!(get_autocrypt_mime(&mail).is_some());
-        assert!(get_mixed_up_mime(&mail).is_none());
-        assert!(get_attachment_mime(&mail).is_none());
-
-        // Another form of "Mixed Up" mail created by Google Workspace,
-        // where original message is turned into attachment to empty plaintext message.
-        let attachment_mime = include_bytes!("../test-data/message/google-workspace-mixed-up.eml");
-        let mail = mailparse::parse_mail(attachment_mime)?;
-        assert!(get_autocrypt_mime(&mail).is_none());
-        assert!(get_mixed_up_mime(&mail).is_none());
-        assert!(get_attachment_mime(&mail).is_some());
-
-        let bob = TestContext::new_bob().await;
-        receive_imf(&bob, attachment_mime, false).await?;
-        let msg = bob.get_last_msg().await;
-        assert_eq!(msg.text.as_deref(), Some("Hello from Thunderbird!"));
-
-        Ok(())
-    }
 }

src/lib.rs

@@ -58,6 +58,7 @@ mod configure;
 pub mod constants;
 pub mod contact;
 pub mod context;
+mod decrypt;
 pub mod download;
 mod e2ee;
 pub mod ephemeral;

src/mimeparser.rs

@@ -15,8 +15,8 @@ use crate::blob::BlobObject;
 use crate::constants::{DC_DESIRED_TEXT_LEN, DC_ELLIPSIS};
 use crate::contact::{addr_cmp, addr_normalize, ContactId};
 use crate::context::Context;
+use crate::decrypt::{create_decryption_info, try_decrypt};
 use crate::dehtml::dehtml;
-use crate::e2ee;
 use crate::events::EventType;
 use crate::format_flowed::unformat_flowed;
 use crate::headerdef::{HeaderDef, HeaderDefMap};
@@ -220,12 +220,11 @@ impl MimeMessage {
         let mut mail_raw = Vec::new();
         let mut gossiped_addr = Default::default();
         let mut from_is_signed = false;
-        let mut decryption_info =
+        let mut decryption_info = create_decryption_info(context, &mail, message_time).await?;
-            e2ee::create_decryption_info(context, &mail, message_time).await?;
 
         // `signatures` is non-empty exactly if the message was encrypted and correctly signed.
         let (mail, signatures, warn_empty_signature) =
-            match e2ee::try_decrypt(context, &mail, &decryption_info).await {
+            match try_decrypt(context, &mail, &decryption_info).await {
                 Ok(Some((raw, signatures))) => {
                     // Encrypted, but maybe unsigned message. Only if
                     // `signatures` set is non-empty, it is a valid

src/peerstate.rs

@@ -9,6 +9,7 @@ use crate::chatlist::Chatlist;
 use crate::constants::Chattype;
 use crate::contact::{addr_cmp, Contact, Origin};
 use crate::context::Context;
+use crate::decrypt::DecryptionInfo;
 use crate::events::EventType;
 use crate::key::{DcKey, Fingerprint, SignedPublicKey};
 use crate::message::Message;
@@ -611,7 +612,7 @@ impl Peerstate {
 /// In `drafts/aeap_mvp.md` there is a "big picture" overview over AEAP.
 pub async fn maybe_do_aeap_transition(
     context: &Context,
-    info: &mut crate::e2ee::DecryptionInfo,
+    info: &mut DecryptionInfo,
     mime_parser: &crate::mimeparser::MimeMessage,
 ) -> Result<()> {
     if let Some(peerstate) = &mut info.peerstate {