Add update_invite extension

src/lib.rs

@@ -42,6 +42,7 @@ pub mod proto {
     pub mod open_invite;
     pub mod redeem_invite;
     pub mod update_cred;
+    pub mod update_invite;
 }
 
 #[cfg(feature = "bridgeauth")]

src/proto/update_invite.rs

@@ -0,0 +1,136 @@
+/*! A module for the protocol for a user to request the issuing of an updated
+ * invitation credential after a key rotation has occurred
+
+
+The user presents their current Invitation credential:
+- id: revealed
+- date: blinded
+- bucket: blinded
+- blockages: blinded
+
+and a new Invitation credential to be issued:
+- id: jointly chosen by the user and BA
+- date: blinded, but proved in ZK that it's the same as in the invitation
+  date above
+- bucket: blinded, but proved in ZK that it's the same as in the Invitation
+  credential above
+- blockages: blinded, but proved in ZK that it's the same as in the
+  Invitation credential above
+
+*/
+
+#[cfg(feature = "bridgeauth")]
+use super::super::dup_filter::SeenType;
+#[cfg(feature = "bridgeauth")]
+use super::super::BridgeAuth;
+use super::errors::CredentialError;
+use crate::lox_creds::Invitation;
+use cmz::*;
+use curve25519_dalek::ristretto::RistrettoPoint as G;
+use group::Group;
+use rand_core::RngCore;
+use sha2::Sha512;
+
+muCMZProtocol! { update_invite,
+    I: Invitation { inv_id: R, date: H, bucket: H, blockages: H },
+    N: Invitation { inv_id: J, date: H, bucket: H, blockages: H },
+    I.date = N.date,
+    I.bucket = N.bucket,
+    I.blockages = N.blockages,
+}
+
+pub fn request(
+    I: Invitation,
+    new_pubkeys: CMZPubkey<G>,
+) -> Result<(update_invite::Request, update_invite::ClientState), CredentialError> {
+    let mut rng = rand::thread_rng();
+    cmz_group_init(G::hash_from_bytes::<Sha512>(b"CMZ Generator A"));
+
+    let N = Invitation::using_pubkey(&new_pubkeys);
+    match update_invite::prepare(&mut rng, &I, N) {
+        Ok(req_state) => Ok(req_state),
+        Err(e) => Err(CredentialError::CMZError(e)),
+    }
+}
+
+#[cfg(feature = "bridgeauth")]
+impl BridgeAuth {
+    pub fn handle_update_invite(
+        &mut self,
+        req: update_invite::Request,
+    ) -> Result<update_invite::Reply, CredentialError> {
+        let mut rng = rand::thread_rng();
+        // Both of these must be true and should be true after rotate_lox_keys is called
+        if self.old_keys.invitation_keys.is_empty() || self.old_filters.invitation_filter.is_empty()
+        {
+            return Err(CredentialError::CredentialMismatch);
+        }
+
+        let reqbytes = req.as_bytes();
+        let recvreq = update_invite::Request::try_from(&reqbytes[..]).unwrap();
+        match update_invite::handle(
+            &mut rng,
+            recvreq,
+            |I: &mut Invitation, N: &mut Invitation| {
+                // calling this function will automatically use the most recent old private key for
+                // verification and the new private key for issuing.
+                // Recompute the "error factors" using knowledge of our own
+                // (the issuer's) outdated private key instead of knowledge of the
+                // hidden attributes
+                let old_keys = match self
+                    .old_keys
+                    .invitation_keys
+                    .iter()
+                    .find(|x| x.pub_key == *I.get_pubkey())
+                {
+                    Some(old_keys) => old_keys,
+                    None => return Err(CMZError::RevealAttrMissing("Key", "Mismatch")),
+                };
+                let old_priv_key = old_keys.priv_key.clone();
+                I.set_privkey(&old_priv_key);
+                N.set_privkey(&self.invitation_priv);
+                I.date = N.date;
+                I.bucket = N.bucket;
+                I.blockages = N.blockages;
+                Ok(())
+            },
+            |I: &Invitation, _N: &Invitation| {
+                let index = match self
+                    .old_keys
+                    .invitation_keys
+                    .iter()
+                    .position(|x| x.pub_key == *I.get_pubkey())
+                {
+                    Some(index) => index,
+                    None => return Err(CMZError::RevealAttrMissing("Key", "Mismatch")),
+                };
+                if self
+                    .old_filters
+                    .invitation_filter
+                    .get_mut(index)
+                    .unwrap()
+                    .filter(&I.inv_id.unwrap())
+                    == SeenType::Seen
+                {
+                    return Err(CMZError::RevealAttrMissing("id", "Credential Expired"));
+                }
+                Ok(())
+            },
+        ) {
+            Ok((response, (_I_issuer, _N_issuer))) => Ok(response),
+            Err(e) => Err(CredentialError::CMZError(e)),
+        }
+    }
+}
+
+pub fn handle_response(
+    state: update_invite::ClientState,
+    rep: update_invite::Reply,
+) -> Result<Invitation, CMZError> {
+    let replybytes = rep.as_bytes();
+    let recvreply = update_invite::Reply::try_from(&replybytes[..]).unwrap();
+    match state.finalize(recvreply) {
+        Ok(cred) => Ok(cred),
+        Err(_e) => Err(CMZError::Unknown),
+    }
+}