diff --git a/crates/lox-library/Cargo.toml b/crates/lox-library/Cargo.toml
index ee389cd..248d432 100644
--- a/crates/lox-library/Cargo.toml
+++ b/crates/lox-library/Cargo.toml
@@ -16,6 +16,7 @@ lazy_static = "1"
 hex_fmt = "0.3"
 aes-gcm = "0.8"
 base64 = "0.13"
+time = "0.2"
 
 [features]
 default = ["u64_backend"]
diff --git a/crates/lox-library/src/lib.rs b/crates/lox-library/src/lib.rs
index 639a231..109ac54 100644
--- a/crates/lox-library/src/lib.rs
+++ b/crates/lox-library/src/lib.rs
@@ -18,6 +18,7 @@ The notation follows that of the paper "Hyphae: Social Secret Sharing"
 extern crate zkp;
 
 pub mod bridge_table;
+pub mod cred;
 pub mod dup_filter;
 
 use sha2::Sha512;
@@ -114,11 +115,11 @@ pub const OPENINV_LENGTH: usize = 32 // the length of the random
 
 impl BridgeDb {
     /// Create the BridgeDb.
-    pub fn new(num_openinv_buckets: u32) -> BridgeDb {
+    pub fn new(num_openinv_buckets: u32) -> Self {
         let mut csprng = OsRng {};
         let keypair = Keypair::generate(&mut csprng);
         let pubkey = keypair.public;
-        BridgeDb {
+        Self {
             keypair,
             pubkey,
             num_openinv_buckets,
@@ -165,3 +166,62 @@ impl BridgeDb {
         }
     }
 }
+
+/// The bridge authority.  This will typically be a singleton object.
+#[derive(Debug)]
+pub struct BridgeAuth {
+    /// The private key for the main Lox credential
+    lox_priv: IssuerPrivKey,
+    /// The public key for the main Lox credential
+    pub lox_pub: IssuerPubKey,
+    /// The private key for migration credentials
+    migration_priv: IssuerPrivKey,
+    /// The public key for migration credentials
+    pub migration_pub: IssuerPubKey,
+
+    /// The public key of the BridgeDb issuing open invitations
+    pub bridgedb_pub: PublicKey,
+
+    /// Duplicate filter for open invitations
+    openinv_filter: dup_filter::DupFilter<Scalar>,
+    /// Duplicate filter for credential ids
+    id_filter: dup_filter::DupFilter<Scalar>,
+
+    /// For testing only: offset of the true time to the simulated time
+    time_offset: time::Duration,
+}
+
+impl BridgeAuth {
+    pub fn new(bridgedb_pub: PublicKey) -> Self {
+        let lox_priv = IssuerPrivKey::new(6);
+        let lox_pub = IssuerPubKey::new(&lox_priv);
+        let migration_priv = IssuerPrivKey::new(3);
+        let migration_pub = IssuerPubKey::new(&migration_priv);
+        Self {
+            lox_priv,
+            lox_pub,
+            migration_priv,
+            migration_pub,
+            bridgedb_pub,
+            openinv_filter: Default::default(),
+            id_filter: Default::default(),
+            time_offset: time::Duration::zero(),
+        }
+    }
+
+    /// For testing only: manually advance the day by 1 day
+    pub fn advance_day(&mut self) {
+        self.time_offset += time::Duration::days(1);
+    }
+
+    /// For testing only: manually advance the day by the given number
+    /// of days
+    pub fn advance_days(&mut self, days: u16) {
+        self.time_offset += time::Duration::days(days.into());
+    }
+
+    /// Get today's (real or simulated) date
+    fn today(&self) -> i64 {
+        (time::OffsetDateTime::now_utc().date() + self.time_offset).julian_day()
+    }
+}
diff --git a/crates/lox-library/tests/tests.rs b/crates/lox-library/tests/tests.rs
index ce497fa..9c67e68 100644
--- a/crates/lox-library/tests/tests.rs
+++ b/crates/lox-library/tests/tests.rs
@@ -1,5 +1,6 @@
 use lox::dup_filter;
 use lox::dup_filter::SeenType::{Fresh, Seen};
+use lox::BridgeAuth;
 use lox::BridgeDb;
 
 use curve25519_dalek::scalar::Scalar;
@@ -44,3 +45,11 @@ fn test_dup_filter() {
     println!("df1 = {:?}", df1);
     println!("df2 = {:?}", df2);
 }
+
+#[test]
+fn test_bridgeauth() {
+    let bdb = BridgeDb::new(20);
+    let mut ba = BridgeAuth::new(bdb.pubkey);
+    ba.advance_day();
+    ba.advance_days(30);
+}