feat(submit): bind submit proof to measurement.

ooniauth-core/benches/bench_client.rs

@@ -96,6 +96,7 @@ fn bench_user_submit_request(c: &mut Criterion) {
     let today = ServerState::today();
     let age_range = (today - 30)..(today + 1);
     let measurement_count_range = 0..100;
+    let measurement_hash = [1u8; 32];
 
     c.bench_function("user.submit_request", |b| {
         b.iter_batched(
@@ -112,6 +113,7 @@ fn bench_user_submit_request(c: &mut Criterion) {
                     &mut rng,
                     "US".to_string(),
                     "AS1234".to_string(),
+                    &measurement_hash,
                     age_range.clone(),
                     measurement_count_range.clone(),
                 )
@@ -129,6 +131,7 @@ fn bench_user_handle_submit_response(c: &mut Criterion) {
     let today = ServerState::today();
     let age_range = (today - 30)..(today + 1);
     let measurement_count_range = 0..100;
+    let measurement_hash = [1u8; 32];
 
     c.bench_function("user.handle_submit_response", |b| {
         b.iter_batched(
@@ -144,6 +147,7 @@ fn bench_user_handle_submit_response(c: &mut Criterion) {
                         &mut rng,
                         "US".to_string(),
                         "AS1234".to_string(),
+                        &measurement_hash,
                         age_range.clone(),
                         measurement_count_range.clone(),
                     )
@@ -155,6 +159,7 @@ fn bench_user_handle_submit_response(c: &mut Criterion) {
                         &nym,
                         "US",
                         "AS1234",
+                        &measurement_hash,
                         age_range.clone(),
                         measurement_count_range.clone(),
                     )

ooniauth-core/benches/bench_server.rs

@@ -38,11 +38,13 @@ fn bench_submit(c: &mut Criterion) {
 
         let age_range = (today - 30)..(today + 1);
         let msm_range = 0..100;
+        let measurement_hash = [1u8; 32];
         let ((req, _), nym) = user
             .submit_request(
                 &mut rng,
                 cc.into(),
                 asn.into(),
+                &measurement_hash,
                 age_range.clone(),
                 msm_range.clone(),
             )
@@ -54,6 +56,7 @@ fn bench_submit(c: &mut Criterion) {
                 black_box(&nym),
                 black_box(cc),
                 black_box(asn),
+                black_box(&measurement_hash),
                 black_box(age_range.clone()),
                 black_box(msm_range.clone()),
             )

ooniauth-core/examples/basic_usage.rs

@@ -1,5 +1,6 @@
 use std::time::Instant;
 
+use ooniauth_core::submit::submit_measurement_hash;
 use ooniauth_core::{scalar_u32, ServerState, UserState};
 use tracing_forest::util::LevelFilter;
 use tracing_forest::ForestLayer;
@@ -97,12 +98,14 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     let today = ServerState::today();
     let age_range = (today - 30)..(today + 1);
     let measurement_count_range = 0..100;
+    let measurement_hash = submit_measurement_hash(b"measurement:US:AS1234");
 
     let now = Instant::now();
     let ((submit_request, submit_state), nym) = user.submit_request(
         &mut rng,
         probe_cc.clone(),
         probe_asn.clone(),
+        &measurement_hash,
         age_range.clone(),
         measurement_count_range.clone(),
     )?;
@@ -130,6 +133,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
         &nym,
         &probe_cc,
         &probe_asn,
+        &measurement_hash,
         age_range,
         measurement_count_range,
     )?;
@@ -175,12 +179,14 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
 
     let age_range2 = (today - 30)..(today + 1);
     let measurement_count_range2 = 0..100;
+    let measurement_hash2 = submit_measurement_hash(b"measurement:UK:AS5678");
 
     let now = Instant::now();
     let ((submit_request2, submit_state2), nym2) = user.submit_request(
         &mut rng,
         probe_cc2.clone(),
         probe_asn2.clone(),
+        &measurement_hash2,
         age_range2.clone(),
         measurement_count_range2.clone(),
     )?;
@@ -203,6 +209,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
         &nym2,
         &probe_cc2,
         &probe_asn2,
+        &measurement_hash2,
         age_range2,
         measurement_count_range2,
     )?;

ooniauth-core/src/registration.rs

@@ -14,7 +14,7 @@ use rand::{CryptoRng, RngCore};
 use sha2::Sha512;
 use tracing::{instrument, trace};
 
-const SESSION_ID: &[u8] = b"registration";
+const SESSION_ID: &[u8] = b"ooni.org/userauth/v1/reg";
 
 CMZ! { UserAuthCredential:
     nym_id,

ooniauth-core/src/submit.rs

@@ -9,8 +9,29 @@ use serde::{Deserialize, Serialize};
 use sha2::{Digest, Sha256, Sha512};
 use tracing::{debug, instrument, trace};
 
-const SESSION_ID: &[u8] = b"submit";
-const PROBE_ID_SALT: &[u8] = b"ooni.org/userauth/v1";
+const PROBE_ID_SALT: &[u8] = b"ooni.org/userauth/v1/pid";
+const SUBMIT_SESSION_ID_SALT: &[u8] = b"ooni.org/v1/sid";
+pub type MeasurementHash = [u8; 32];
+pub type SubmitSessionId = [u8; 32];
+
+/// Hash measurement material for submit proof binding.
+pub fn submit_measurement_hash(measurement: &[u8]) -> MeasurementHash {
+    let measurement_hash = Sha256::digest(measurement);
+    let mut out = [0u8; 32];
+    out.copy_from_slice(&measurement_hash);
+    out
+}
+
+/// Derive the submit proof session ID from a 32-byte measurement hash.
+pub fn submit_session_id(measurement_hash: &MeasurementHash) -> SubmitSessionId {
+    let mut hasher = Sha256::new();
+    hasher.update(SUBMIT_SESSION_ID_SALT);
+    hasher.update(measurement_hash);
+    let digest = hasher.finalize();
+    let mut out = [0u8; 32];
+    out.copy_from_slice(&digest);
+    out
+}
 
 muCMZProtocol!(submit<min_age_today, max_age, min_measurement_count,
         max_measurement_count, @DOMAIN, @NYM>,
@@ -57,12 +78,21 @@ fn digest_point(point: RistrettoPoint) -> [u8; 32] {
 }
 
 impl UserState {
-    #[instrument(skip(self, rng, probe_cc, probe_asn, age_range, measurement_count_range))]
+    #[instrument(skip(
+        self,
+        rng,
+        probe_cc,
+        probe_asn,
+        measurement_hash,
+        age_range,
+        measurement_count_range
+    ))]
     pub fn submit_request(
         &self,
         rng: &mut (impl RngCore + CryptoRng),
         probe_cc: String,
         probe_asn: String,
+        measurement_hash: &MeasurementHash,
         age_range: std::ops::Range<u32>,
         measurement_count_range: std::ops::Range<u32>,
     ) -> Result<((SubmitRequest, submit::ClientState), [u8; 32]), CredentialError> {
@@ -153,7 +183,8 @@ impl UserState {
         };
 
         trace!("Preparing submit proof with params");
-        match submit::prepare(rng, SESSION_ID, Old, New, &params) {
+        let session_id = submit_session_id(measurement_hash);
+        match submit::prepare(rng, &session_id, Old, New, &params) {
             Ok((core_request, client_state)) => {
                 debug!("Submit request prepared successfully");
                 let probe_id = digest_point(NYM);
@@ -196,6 +227,7 @@ impl ServerState {
         probe_id,
         probe_cc,
         probe_asn,
+        measurement_hash,
         age_range,
         measurement_count_range
     ))]
@@ -206,6 +238,7 @@ impl ServerState {
         probe_id: &[u8; 32],
         probe_cc: &str,
         probe_asn: &str,
+        measurement_hash: &MeasurementHash,
         age_range: std::ops::Range<u32>,
         measurement_count_range: std::ops::Range<u32>,
     ) -> Result<submit::Reply, CMZError> {
@@ -238,9 +271,10 @@ impl ServerState {
 
         let server_sk = self.sk.clone();
         let server_pp = self.pp.clone();
+        let session_id = submit_session_id(measurement_hash);
         match submit::handle(
             rng,
-            SESSION_ID,
+            &session_id,
             recvreq,
             move |Old: &mut UserAuthCredential, New: &mut UserAuthCredential| {
                 // Set the private key for the credentials - this is essential for the protocol
@@ -336,11 +370,13 @@ mod tests {
         let today = ServerState::today();
         let age_range = (today - 30)..(today + 1); // Credential valid for 30 days
         let measurement_count_range = 0..100;
+        let measurement_hash = submit_measurement_hash(b"measurement:US:AS1234");
 
         let result = user_state.submit_request(
             rng,
             probe_cc.clone(),
             probe_asn.clone(),
+            &measurement_hash,
             age_range.clone(),
             measurement_count_range.clone(),
         );
@@ -367,6 +403,7 @@ mod tests {
             &nym,
             &probe_cc,
             &probe_asn,
+            &measurement_hash,
             age_range,
             measurement_count_range,
         );
@@ -394,4 +431,69 @@ mod tests {
         let new_count = scalar_u32(&updated_cred.measurement_count.unwrap()).unwrap();
         assert_eq!(new_count, 1, "Measurement count should be incremented to 1");
     }
+
+    #[test]
+    fn test_submit_request_rejects_replaced_measurement() {
+        let rng = &mut rand::thread_rng();
+
+        let server_state = ServerState::new(rng);
+        let mut user_state = UserState::new(server_state.public_parameters());
+
+        let (reg_request, reg_client_state) = user_state.request(rng).unwrap();
+        let reg_response = server_state.open_registration(reg_request).unwrap();
+        user_state
+            .handle_response(reg_client_state, reg_response)
+            .unwrap();
+
+        let probe_cc = "US".to_string();
+        let probe_asn = "AS1234".to_string();
+        let today = ServerState::today();
+        let age_range = (today - 30)..(today + 1);
+        let measurement_count_range = 0..100;
+        let original_measurement_hash = submit_measurement_hash(b"measurement:US:AS1234");
+        let replaced_measurement_hash = submit_measurement_hash(b"measurement:US:AS1234:replaced");
+
+        let ((request, _client_state), nym) = user_state
+            .submit_request(
+                rng,
+                probe_cc.clone(),
+                probe_asn.clone(),
+                &original_measurement_hash,
+                age_range.clone(),
+                measurement_count_range.clone(),
+            )
+            .unwrap();
+
+        assert_ne!(original_measurement_hash, replaced_measurement_hash);
+
+        let replaced_result = server_state.handle_submit(
+            rng,
+            request.clone(),
+            &nym,
+            &probe_cc,
+            &probe_asn,
+            &replaced_measurement_hash,
+            age_range.clone(),
+            measurement_count_range.clone(),
+        );
+        assert!(
+            replaced_result.is_err(),
+            "Server should reject a submit request verified against a replaced measurement"
+        );
+
+        let original_result = server_state.handle_submit(
+            rng,
+            request,
+            &nym,
+            &probe_cc,
+            &probe_asn,
+            &original_measurement_hash,
+            age_range,
+            measurement_count_range,
+        );
+        assert!(
+            original_result.is_ok(),
+            "Server should accept the submit request with the original measurement session ID"
+        );
+    }
 }

ooniauth-core/src/update.rs

@@ -6,7 +6,7 @@ use group::Group;
 use rand::{CryptoRng, RngCore};
 use sha2::Sha512;
 
-const SESSION_ID: &[u8] = b"update";
+const SESSION_ID: &[u8] = b"ooni.org/userauth/v1/upd";
 
 muCMZProtocol!(update,
     Old: UserAuthCredential { nym_id: H, age: H, measurement_count: H},

ooniauth-ffi/src/lib.rs

@@ -3,6 +3,7 @@ use std::sync::Once;
 use std::time::Instant;
 
 use ooniauth_core::registration::UserAuthCredential;
+use ooniauth_core::submit::submit_measurement_hash;
 use ooniauth_core::{scalar_u32, ServerState, UserState};
 use tracing_forest::util::LevelFilter;
 use tracing_forest::ForestLayer;
@@ -159,13 +160,15 @@ fn run_basic_usage_demo() -> Result<String, String> {
     let today = ServerState::today();
     let age_range = (today - 30)..(today + 1);
     let measurement_count_range = 0..100;
+    let measurement_hash = submit_measurement_hash(b"measurement:US:AS1234");
 
     let now = Instant::now();
     let ((submit_request, submit_state), nym) = user
         .submit_request(
             &mut rng,
             probe_cc.clone(),
             probe_asn.clone(),
+            &measurement_hash,
             age_range.clone(),
             measurement_count_range.clone(),
         )
@@ -193,6 +196,7 @@ fn run_basic_usage_demo() -> Result<String, String> {
             &nym,
             &probe_cc,
             &probe_asn,
+            &measurement_hash,
             age_range,
             measurement_count_range,
         )
@@ -234,13 +238,15 @@ fn run_basic_usage_demo() -> Result<String, String> {
 
     let age_range2 = (today - 30)..(today + 1);
     let measurement_count_range2 = 0..100;
+    let measurement_hash2 = submit_measurement_hash(b"measurement:UK:AS5678");
 
     let now = Instant::now();
     let ((submit_request2, submit_state2), nym2) = user
         .submit_request(
             &mut rng,
             probe_cc2.clone(),
             probe_asn2.clone(),
+            &measurement_hash2,
             age_range2.clone(),
             measurement_count_range2.clone(),
         )
@@ -264,6 +270,7 @@ fn run_basic_usage_demo() -> Result<String, String> {
             &nym2,
             &probe_cc2,
             &probe_asn2,
+            &measurement_hash2,
             age_range2,
             measurement_count_range2,
         )

ooniauth-py/ooniauth_py.pyi

@@ -48,6 +48,7 @@ class ServerState:
         request: str,
         probe_cc: str,
         probe_asn: str,
+        measurement_hash: str,
         age_range: tuple[builtins.int, builtins.int],
         min_measurement_count: builtins.int,
     ) -> str: ...
@@ -78,6 +79,7 @@ class UserState:
         self,
         probe_cc: str,
         probe_asn: str,
+        measurement_hash: str,
         age_range: tuple[builtins.int, builtins.int],
         min_measurement_count: builtins.int,
     ) -> SubmitRequest: ...