crypto(feat): Key distribution errors for pin violations

crates/matrix-sdk-crypto/src/error.rs

@@ -70,6 +70,35 @@ pub enum OlmError {
             have a valid Olm session with us"
     )]
     MissingSession,
+
+    #[error(transparent)]
+    /// The room key that was to be shared was not shared because the sharing
+    /// strategy could not be fulfilled.
+    RoomKeySharingStrategyError(RoomKeySharingStrategyError),
+}
+
+/// Depending on the sharing strategy for room keys, the distribution of the
+/// room key could fail.
+#[derive(Error, Debug)]
+pub enum RoomKeySharingStrategyError {
+    /// When encrypting using the IdentityBased strategy, and there are changed
+    /// user identities that have not been confirmed by the user. The
+    /// application should display identity changes to the user as soon as
+    /// possible to avoid hitting this case. If this happens the app might just
+    /// retry automatically after the identity change has been notified, or
+    /// offer option to cancel.
+    #[error("Encryption failed because changed user identities have not been confirmed, please confirm or verify the problematic user identities")]
+    UnconfirmedIdentities(Vec<OwnedUserId>),
+
+    /// Cross-signing is required for encryption with invisible crypto
+    #[error("Encryption failed because cross-signing is not setup on your account")]
+    CrossSigningNotSetup,
+
+    /// The current device needs to be verified when encrypting using the
+    /// IdentityBased strategy. Apps should prevent sending in the UI to
+    /// avoid hitting this case.
+    #[error("Encryption failed because your device is not verified")]
+    SendingFromUnverifiedDevice,
 }
 
 /// Error representing a failure during a group encryption operation.