v1.10.0: MMUR2 signed claims (claims feature), DiscoveryRecord/EnrichPatch carry claims, meta-core writes post signed claims

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "meta-feeder-sdk"
-version = "1.9.0"
+version = "1.10.0"
 edition = "2021"
 rust-version = "1.85"
 license = "MIT"
@@ -37,7 +37,7 @@ default = ["feeder"]
 # FeederPlugin trait, hashing, the redb cache, the axum harness. On by default
 # so existing consumers build exactly what they always did.
 feeder = [
-    "beacon", "filename",
+    "beacon", "filename", "claims",
     "dep:axum", "dep:hyper", "dep:reqwest", "dep:base64", "dep:futures",
     "dep:async-trait", "dep:anyhow", "dep:thiserror", "dep:sha2", "dep:bytes",
     "dep:redb",
@@ -56,6 +56,15 @@ beacon = ["dep:libc"]
 transport = ["feeder", "dep:cid", "dep:tokio-util"]
 # Conformance checks any transport implementation must pass.
 testkit = ["transport"]
+# MMUR2 signed claims (`src/claims.rs`): the `SignedClaim` type, its canonical
+# bytes, signing (k256, compact low-S), verification and the writer key
+# (`METAMESH_SIGNING_KEY` / `_FILE`). `feeder` enables it because the gateway
+# wire (`DiscoveryRecord`, `EnrichPatch`) carries claims; a meta-* service that
+# only needs claims takes `default-features = false, features = ["claims"]`.
+claims = [
+    "dep:k256", "dep:bs58", "dep:sha2", "dep:base64", "dep:rand_core",
+    "dep:anyhow", "dep:thiserror",
+]
 
 [dependencies]
 # Async runtime + HTTP server (the serve_feeders harness)
@@ -80,6 +89,11 @@ bytes = { version = "1", optional = true }
 # Title-tag parsing (shared filename_meta — season/episode/quality/codec/languages).
 regex = { version = "1", optional = true }
 
+# MMUR2 claims (the `claims` feature).
+k256 = { version = "0.13", features = ["ecdsa", "std"], optional = true }
+bs58 = { version = "0.5", optional = true }
+rand_core = { version = "0.6", features = ["getrandom"], optional = true }
+
 # Per-plugin midhash/blob cache. Schema is identical to meta-share v1 — see
 # cache.rs. Pure-Rust single-process embedded store.
 redb = { version = "2", optional = true }

src/claims.rs

@@ -0,0 +1,602 @@
+//! MMUR2 signed claims: signer `uid` says `key = value` about content `cid`, at
+//! `ts` (milliseconds, also the version). See meta-root
+//! `docs/implementation/metacore-claims-model.md` §3.
+//!
+//! Wire spec (pinned by `tests/claim-vectors.json`, vendored from meta-core's
+//! `internal/claim/testdata` — `scripts/check-claim-vectors.sh` guards it):
+//!
+//! ```text
+//! domain        = b"MMUR2\n"
+//! payload       = canonical CBOR array [cid, uid, key, value, ts]
+//! bytes_to_sign = domain || payload
+//! sig           = ECDSA-secp256k1(SHA-256(bytes_to_sign)), compact r||s, low-S
+//! ```
+//!
+//! `value` is CBOR text (public), bytes (private envelope) or null (retraction).
+//! The encoder is hand-rolled: those five shapes are all MMUR2 needs, and a
+//! hand-rolled head encoder cannot drift from "smallest integer form".
+//!
+//! The type and its JSON form are always available with the `feeder` feature
+//! (the gateway wire carries claims); signing and verification are here too,
+//! behind `claims`, which `feeder` enables.
+
+use std::collections::BTreeMap;
+
+use base64::Engine as _;
+use serde::{de, Deserialize, Deserializer, Serialize, Serializer};
+
+/// Domain separator. Changing it invalidates every claim everywhere.
+pub const DOMAIN: &[u8] = b"MMUR2\n";
+
+/// A claim's value. The SQLite storage type in meta-core mirrors it.
+#[derive(Clone, Debug, PartialEq, Eq, Default)]
+pub enum ClaimValue {
+    /// Retraction (tombstone).
+    #[default]
+    Null,
+    /// Public plaintext.
+    Text(String),
+    /// Private envelope (XChaCha20-Poly1305), opaque to everyone but the owner.
+    Bytes(Vec<u8>),
+}
+
+impl ClaimValue {
+    pub fn is_null(&self) -> bool {
+        matches!(self, ClaimValue::Null)
+    }
+    pub fn as_text(&self) -> Option<&str> {
+        match self {
+            ClaimValue::Text(s) => Some(s),
+            _ => None,
+        }
+    }
+}
+
+/// One signed vote.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub struct SignedClaim {
+    pub cid: String,
+    pub uid: String,
+    pub key: String,
+    #[serde(with = "value_json")]
+    pub value: ClaimValue,
+    pub ts: u64,
+    /// 64-byte compact r||s, base64 in JSON.
+    #[serde(with = "sig_b64")]
+    pub sig: Vec<u8>,
+}
+
+impl SignedClaim {
+    /// The exact bytes the signature covers.
+    pub fn signed_bytes(&self) -> Vec<u8> {
+        signed_bytes(&self.cid, &self.uid, &self.key, &self.value, self.ts)
+    }
+}
+
+/// `domain || canonical CBOR [cid, uid, key, value, ts]`.
+pub fn signed_bytes(cid: &str, uid: &str, key: &str, value: &ClaimValue, ts: u64) -> Vec<u8> {
+    let extra = match value {
+        ClaimValue::Text(s) => s.len(),
+        ClaimValue::Bytes(b) => b.len(),
+        ClaimValue::Null => 0,
+    };
+    let mut b = Vec::with_capacity(DOMAIN.len() + cid.len() + uid.len() + key.len() + extra + 32);
+    b.extend_from_slice(DOMAIN);
+    head(&mut b, 4, 5);
+    text(&mut b, cid);
+    text(&mut b, uid);
+    text(&mut b, key);
+    match value {
+        ClaimValue::Text(s) => text(&mut b, s),
+        ClaimValue::Bytes(bytes) => {
+            head(&mut b, 2, bytes.len() as u64);
+            b.extend_from_slice(bytes);
+        }
+        ClaimValue::Null => b.push(0xf6),
+    }
+    head(&mut b, 0, ts);
+    b
+}
+
+fn text(b: &mut Vec<u8>, s: &str) {
+    head(b, 3, s.len() as u64);
+    b.extend_from_slice(s.as_bytes());
+}
+
+/// CBOR major type + argument, smallest form.
+fn head(b: &mut Vec<u8>, major: u8, n: u64) {
+    let m = major << 5;
+    if n < 24 {
+        b.push(m | n as u8);
+    } else if n <= 0xff {
+        b.extend_from_slice(&[m | 24, n as u8]);
+    } else if n <= 0xffff {
+        b.push(m | 25);
+        b.extend_from_slice(&(n as u16).to_be_bytes());
+    } else if n <= 0xffff_ffff {
+        b.push(m | 26);
+        b.extend_from_slice(&(n as u32).to_be_bytes());
+    } else {
+        b.push(m | 27);
+        b.extend_from_slice(&n.to_be_bytes());
+    }
+}
+
+/// JSON (human-readable) uses the spec §3.4 form — a string, `{"b64": …}` or
+/// `null`. Binary formats (the bincode gateway wire) use a plain tagged enum:
+/// bincode cannot decode the untagged JSON shape.
+mod value_json {
+    use super::*;
+
+    #[derive(Serialize, Deserialize)]
+    struct B64 {
+        b64: String,
+    }
+
+    #[derive(Serialize, Deserialize)]
+    enum Wire {
+        Null,
+        Text(String),
+        Bytes(Vec<u8>),
+    }
+
+    pub fn serialize<S: Serializer>(v: &ClaimValue, s: S) -> Result<S::Ok, S::Error> {
+        if !s.is_human_readable() {
+            let w = match v {
+                ClaimValue::Null => Wire::Null,
+                ClaimValue::Text(t) => Wire::Text(t.clone()),
+                ClaimValue::Bytes(b) => Wire::Bytes(b.clone()),
+            };
+            return w.serialize(s);
+        }
+        match v {
+            ClaimValue::Null => s.serialize_none(),
+            ClaimValue::Text(t) => s.serialize_str(t),
+            ClaimValue::Bytes(b) => B64 {
+                b64: base64::engine::general_purpose::STANDARD.encode(b),
+            }
+            .serialize(s),
+        }
+    }
+
+    pub fn deserialize<'de, D: Deserializer<'de>>(d: D) -> Result<ClaimValue, D::Error> {
+        if !d.is_human_readable() {
+            return Ok(match Wire::deserialize(d)? {
+                Wire::Null => ClaimValue::Null,
+                Wire::Text(t) => ClaimValue::Text(t),
+                Wire::Bytes(b) => ClaimValue::Bytes(b),
+            });
+        }
+        #[derive(Deserialize)]
+        #[serde(untagged)]
+        enum Raw {
+            Text(String),
+            Bytes(B64),
+        }
+        Ok(match Option::<Raw>::deserialize(d)? {
+            None => ClaimValue::Null,
+            Some(Raw::Text(t)) => ClaimValue::Text(t),
+            Some(Raw::Bytes(B64 { b64 })) => ClaimValue::Bytes(
+                base64::engine::general_purpose::STANDARD
+                    .decode(b64)
+                    .map_err(de::Error::custom)?,
+            ),
+        })
+    }
+}
+
+/// base64 in JSON, raw bytes in binary formats.
+mod sig_b64 {
+    use super::*;
+
+    pub fn serialize<S: Serializer>(v: &[u8], s: S) -> Result<S::Ok, S::Error> {
+        if !s.is_human_readable() {
+            // A plain sequence, symmetric with `Vec::<u8>::deserialize` below.
+            return v.serialize(s);
+        }
+        s.serialize_str(&base64::engine::general_purpose::STANDARD.encode(v))
+    }
+
+    pub fn deserialize<'de, D: Deserializer<'de>>(d: D) -> Result<Vec<u8>, D::Error> {
+        if !d.is_human_readable() {
+            return Vec::<u8>::deserialize(d);
+        }
+        let s = String::deserialize(d)?;
+        base64::engine::general_purpose::STANDARD
+            .decode(s)
+            .map_err(de::Error::custom)
+    }
+}
+
+/// Union-flatten a claim list into a field map: every key that has at least
+/// one non-retracted text vote, with the first such value seen. A
+/// **superset view for filtering and scoring**, not a merge — the merge (most
+/// signers → oldest ts → smallest value, own vote first) lives only in
+/// meta-core (`POST /api/merge`). Ciphertext never appears.
+pub fn union_fields(claims: &[SignedClaim]) -> BTreeMap<String, String> {
+    let mut out = BTreeMap::new();
+    for c in claims {
+        if let ClaimValue::Text(v) = &c.value {
+            out.entry(c.key.clone()).or_insert_with(|| v.clone());
+        }
+    }
+    out
+}
+
+#[cfg(feature = "claims")]
+pub use crypto::*;
+
+#[cfg(feature = "claims")]
+mod crypto {
+    use super::*;
+
+    use k256::ecdsa::signature::hazmat::{PrehashSigner, PrehashVerifier};
+    use k256::ecdsa::{Signature, SigningKey, VerifyingKey};
+    use sha2::{Digest, Sha256};
+
+    /// Why a claim failed verification.
+    #[derive(Debug, thiserror::Error)]
+    pub enum ClaimError {
+        #[error("claim: missing cid or key")]
+        Shape,
+        #[error("uid: {0}")]
+        Uid(String),
+        #[error("sig: want a 64-byte compact signature")]
+        SigLen,
+        #[error("sig: high-S signatures are refused (MMUR2 is low-S only)")]
+        HighS,
+        #[error("sig: does not verify")]
+        Invalid,
+    }
+
+    /// Recover the verifying key a uid encodes (`"z" + base58btc(33-byte sec1)`).
+    pub fn pubkey_from_uid(uid: &str) -> Result<VerifyingKey, ClaimError> {
+        let body = uid
+            .strip_prefix('z')
+            .ok_or_else(|| ClaimError::Uid("missing multibase 'z' prefix".into()))?;
+        let raw = bs58::decode(body)
+            .into_vec()
+            .map_err(|e| ClaimError::Uid(e.to_string()))?;
+        if raw.len() != 33 {
+            return Err(ClaimError::Uid(format!(
+                "pubkey is {} bytes, want 33",
+                raw.len()
+            )));
+        }
+        VerifyingKey::from_sec1_bytes(&raw).map_err(|e| ClaimError::Uid(e.to_string()))
+    }
+
+    /// The uid of a verifying key.
+    pub fn uid_from_pubkey(vk: &VerifyingKey) -> String {
+        let point = vk.to_encoded_point(true);
+        format!("z{}", bs58::encode(point.as_bytes()).into_string())
+    }
+
+    impl SignedClaim {
+        /// Check shape, low-S and the signature against the uid's key.
+        pub fn verify(&self) -> Result<(), ClaimError> {
+            if self.cid.is_empty() || self.key.is_empty() {
+                return Err(ClaimError::Shape);
+            }
+            if self.sig.len() != 64 {
+                return Err(ClaimError::SigLen);
+            }
+            let sig = Signature::from_slice(&self.sig).map_err(|_| ClaimError::Invalid)?;
+            if sig.normalize_s().is_some() {
+                return Err(ClaimError::HighS);
+            }
+            let vk = pubkey_from_uid(&self.uid)?;
+            let digest = Sha256::digest(self.signed_bytes());
+            vk.verify_prehash(&digest, &sig)
+                .map_err(|_| ClaimError::Invalid)
+        }
+    }
+
+    /// A writer's identity: one key per writing container (spec D2).
+    #[derive(Clone)]
+    pub struct Signer {
+        key: SigningKey,
+        uid: String,
+    }
+
+    impl std::fmt::Debug for Signer {
+        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+            f.debug_struct("Signer")
+                .field("uid", &self.uid)
+                .finish_non_exhaustive()
+        }
+    }
+
+    impl Signer {
+        /// From a 32-byte secret, hex (optionally `0x`-prefixed).
+        pub fn from_hex(hex_key: &str) -> anyhow::Result<Self> {
+            let s = hex_key.trim();
+            let s = s
+                .strip_prefix("0x")
+                .or_else(|| s.strip_prefix("0X"))
+                .unwrap_or(s);
+            let raw = decode_hex(s).ok_or_else(|| anyhow::anyhow!("signing key is not hex"))?;
+            if raw.len() != 32 {
+                anyhow::bail!("signing key must be 32 bytes, got {}", raw.len());
+            }
+            let key = SigningKey::from_slice(&raw)
+                .map_err(|e| anyhow::anyhow!("invalid signing key: {e}"))?;
+            let uid = uid_from_pubkey(key.verifying_key());
+            Ok(Signer { key, uid })
+        }
+
+        /// A fresh random key.
+        pub fn generate() -> Self {
+            let key = SigningKey::random(&mut rand_core::OsRng);
+            let uid = uid_from_pubkey(key.verifying_key());
+            Signer { key, uid }
+        }
+
+        pub fn uid(&self) -> &str {
+            &self.uid
+        }
+
+        /// The secret as lowercase hex (for writing a generated key file).
+        pub fn secret_hex(&self) -> String {
+            self.key
+                .to_bytes()
+                .iter()
+                .map(|b| format!("{b:02x}"))
+                .collect()
+        }
+
+        /// Sign one claim at `ts`. RFC 6979 deterministic, normalised to low-S.
+        pub fn sign(&self, cid: &str, key: &str, value: ClaimValue, ts: u64) -> SignedClaim {
+            let bytes = signed_bytes(cid, &self.uid, key, &value, ts);
+            let digest = Sha256::digest(&bytes);
+            let sig: Signature = self
+                .key
+                .sign_prehash(&digest)
+                .expect("a 32-byte prehash always signs");
+            let sig = sig.normalize_s().unwrap_or(sig);
+            SignedClaim {
+                cid: cid.to_string(),
+                uid: self.uid.clone(),
+                key: key.to_string(),
+                value,
+                ts,
+                sig: sig.to_bytes().to_vec(),
+            }
+        }
+
+        /// Sign every field of a flat map as text claims on `cid`, all at `ts`.
+        pub fn sign_fields(
+            &self,
+            cid: &str,
+            fields: &BTreeMap<String, String>,
+            ts: u64,
+        ) -> Vec<SignedClaim> {
+            fields
+                .iter()
+                .map(|(k, v)| self.sign(cid, k, ClaimValue::Text(v.clone()), ts))
+                .collect()
+        }
+
+        /// A signed retraction of `key` on `cid`.
+        pub fn retract(&self, cid: &str, key: &str, ts: u64) -> SignedClaim {
+            self.sign(cid, key, ClaimValue::Null, ts)
+        }
+    }
+
+    /// Milliseconds since the epoch — the `ts` of a claim signed now. Strictly
+    /// increasing per process: `ts` is the version, so two writes to one key in
+    /// the same millisecond must not make the second one `stale`.
+    pub fn now_ms() -> u64 {
+        use std::sync::atomic::{AtomicU64, Ordering};
+        static LAST: AtomicU64 = AtomicU64::new(0);
+        let wall = std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .map(|d| d.as_millis() as u64)
+            .unwrap_or(0);
+        let mut last = LAST.load(Ordering::Relaxed);
+        loop {
+            let next = wall.max(last + 1);
+            match LAST.compare_exchange_weak(last, next, Ordering::Relaxed, Ordering::Relaxed) {
+                Ok(_) => return next,
+                Err(seen) => last = seen,
+            }
+        }
+    }
+
+    /// Env var holding the signer's secret as hex.
+    pub const SIGNING_KEY_ENV: &str = "METAMESH_SIGNING_KEY";
+    /// Env var naming a key file (bind-mounted); generated on first boot.
+    pub const SIGNING_KEY_FILE_ENV: &str = "METAMESH_SIGNING_KEY_FILE";
+
+    /// The writer's key (spec §9): `METAMESH_SIGNING_KEY` (hex) wins; else
+    /// `METAMESH_SIGNING_KEY_FILE`, generated and written (mode 0600) when the
+    /// file does not exist yet. Neither set → error: a writer must never sign
+    /// with a silent ephemeral identity.
+    pub fn load_or_create_key() -> anyhow::Result<Signer> {
+        if let Some(hex) = env_nonempty(SIGNING_KEY_ENV) {
+            return Signer::from_hex(&hex);
+        }
+        let Some(path) = env_nonempty(SIGNING_KEY_FILE_ENV) else {
+            anyhow::bail!("no signing key: set {SIGNING_KEY_ENV} or {SIGNING_KEY_FILE_ENV}");
+        };
+        load_or_create_key_file(std::path::Path::new(&path))
+    }
+
+    /// Read a hex key file, or generate one there (mode 0600) if absent.
+    pub fn load_or_create_key_file(path: &std::path::Path) -> anyhow::Result<Signer> {
+        match std::fs::read_to_string(path) {
+            Ok(s) => Signer::from_hex(&s),
+            Err(e) if e.kind() == std::io::ErrorKind::NotFound => {
+                let signer = Signer::generate();
+                if let Some(dir) = path.parent() {
+                    std::fs::create_dir_all(dir)?;
+                }
+                write_secret(path, &signer.secret_hex())?;
+                tracing::info!(target: "meta-feeder::claims", uid = %signer.uid(),
+                               path = %path.display(), "generated a new signing key");
+                Ok(signer)
+            }
+            Err(e) => Err(anyhow::anyhow!("read signing key {}: {e}", path.display())),
+        }
+    }
+
+    #[cfg(unix)]
+    fn write_secret(path: &std::path::Path, hex: &str) -> std::io::Result<()> {
+        use std::io::Write;
+        use std::os::unix::fs::OpenOptionsExt;
+        let mut f = std::fs::OpenOptions::new()
+            .write(true)
+            .create_new(true)
+            .mode(0o600)
+            .open(path)?;
+        f.write_all(hex.as_bytes())?;
+        f.write_all(b"\n")
+    }
+
+    #[cfg(not(unix))]
+    fn write_secret(path: &std::path::Path, hex: &str) -> std::io::Result<()> {
+        std::fs::write(path, format!("{hex}\n"))
+    }
+
+    fn env_nonempty(key: &str) -> Option<String> {
+        std::env::var(key)
+            .ok()
+            .map(|s| s.trim().to_string())
+            .filter(|s| !s.is_empty())
+    }
+
+    fn decode_hex(s: &str) -> Option<Vec<u8>> {
+        if s.len() % 2 != 0 {
+            return None;
+        }
+        (0..s.len())
+            .step_by(2)
+            .map(|i| u8::from_str_radix(&s[i..i + 2], 16).ok())
+            .collect()
+    }
+
+    #[cfg(test)]
+    mod tests {
+        use super::*;
+
+        #[derive(Deserialize)]
+        struct Vector {
+            name: String,
+            cid: String,
+            uid: String,
+            key: String,
+            value: Option<String>,
+            #[serde(rename = "valueBytesHex")]
+            value_bytes_hex: Option<String>,
+            ts: u64,
+            #[serde(rename = "signedBytesHex")]
+            signed: String,
+            #[serde(rename = "sigHex")]
+            sig: String,
+        }
+        #[derive(Deserialize)]
+        struct HighS {
+            vector: String,
+            #[serde(rename = "sigHex")]
+            sig: String,
+        }
+        #[derive(Deserialize)]
+        struct File {
+            #[serde(rename = "privateKeyHex")]
+            private_key_hex: String,
+            uid: String,
+            vectors: Vec<Vector>,
+            #[serde(rename = "highS")]
+            high_s: HighS,
+        }
+
+        fn hex(b: &[u8]) -> String {
+            b.iter().map(|x| format!("{x:02x}")).collect()
+        }
+
+        fn load() -> File {
+            serde_json::from_str(include_str!("../tests/claim-vectors.json")).unwrap()
+        }
+
+        fn value(v: &Vector) -> ClaimValue {
+            match (&v.value_bytes_hex, &v.value) {
+                (Some(h), _) => ClaimValue::Bytes(decode_hex(h).unwrap()),
+                (None, Some(t)) => ClaimValue::Text(t.clone()),
+                (None, None) => ClaimValue::Null,
+            }
+        }
+
+        #[test]
+        fn golden_vectors() {
+            let f = load();
+            let signer = Signer::from_hex(&f.private_key_hex).unwrap();
+            assert_eq!(signer.uid(), f.uid);
+            for v in &f.vectors {
+                let c = signer.sign(&v.cid, &v.key, value(v), v.ts);
+                assert_eq!(c.uid, v.uid, "{}", v.name);
+                assert_eq!(hex(&c.signed_bytes()), v.signed, "{}: signed bytes", v.name);
+                assert_eq!(hex(&c.sig), v.sig, "{}: RFC 6979 signature", v.name);
+                c.verify().unwrap_or_else(|e| panic!("{}: {e}", v.name));
+                // JSON round trip keeps the claim verifiable.
+                let back: SignedClaim =
+                    serde_json::from_str(&serde_json::to_string(&c).unwrap()).unwrap();
+                assert_eq!(back, c, "{}: json", v.name);
+            }
+            let v = f
+                .vectors
+                .iter()
+                .find(|v| v.name == f.high_s.vector)
+                .unwrap();
+            let high = SignedClaim {
+                cid: v.cid.clone(),
+                uid: v.uid.clone(),
+                key: v.key.clone(),
+                value: value(v),
+                ts: v.ts,
+                sig: decode_hex(&f.high_s.sig).unwrap(),
+            };
+            assert!(matches!(high.verify(), Err(ClaimError::HighS)));
+        }
+
+        #[test]
+        fn tamper_is_refused() {
+            let s = Signer::generate();
+            let mut c = s.sign("bafy", "title", ClaimValue::Text("A".into()), 1);
+            c.value = ClaimValue::Text("B".into());
+            assert!(matches!(c.verify(), Err(ClaimError::Invalid)));
+        }
+
+        #[test]
+        fn key_file_is_generated_once() {
+            let dir = tempfile::tempdir().unwrap();
+            let p = dir.path().join("keys/signing.key");
+            let a = load_or_create_key_file(&p).unwrap();
+            let b = load_or_create_key_file(&p).unwrap();
+            assert_eq!(a.uid(), b.uid());
+        }
+
+        #[test]
+        fn json_shapes() {
+            let s = Signer::generate();
+            let j =
+                serde_json::to_value(s.sign("c", "k", ClaimValue::Bytes(vec![1, 2]), 5)).unwrap();
+            assert_eq!(j["value"]["b64"], "AQI=");
+            let j = serde_json::to_value(s.retract("c", "k", 6)).unwrap();
+            assert!(j["value"].is_null());
+        }
+
+        #[test]
+        fn union_keeps_first_text_and_skips_retractions_and_cipher() {
+            let s = Signer::generate();
+            let claims = vec![
+                s.sign("c", "title", ClaimValue::Text("A".into()), 1),
+                s.sign("c", "title", ClaimValue::Text("B".into()), 2),
+                s.retract("c", "gone", 3),
+                s.sign("c", "seek", ClaimValue::Bytes(vec![9]), 4),
+            ];
+            let f = union_fields(&claims);
+            assert_eq!(f.get("title").map(String::as_str), Some("A"));
+            assert!(!f.contains_key("gone") && !f.contains_key("seek"));
+        }
+    }
+}

src/enrich.rs

@@ -64,6 +64,10 @@ pub struct EnrichmentConfig {
     pub opensubtitles_password: Option<String>,
     /// Wanted subtitle languages (CSV of ISO 639-1 codes; default `en`).
     pub opensubtitles_languages: String,
+    /// This feeder's claim signer (`METAMESH_SIGNING_KEY` / `_FILE`). `None`
+    /// when no key is configured: every meta-core write then fails loudly
+    /// instead of publishing unsigned data.
+    pub signer: Option<crate::claims::Signer>,
 }
 
 fn env_nonempty(key: &str) -> Option<String> {
@@ -120,6 +124,14 @@ impl EnrichmentConfig {
             opensubtitles_password: env_nonempty("OPENSUBTITLES_PASSWORD"),
             opensubtitles_languages: env_nonempty("OPENSUBTITLES_LANGUAGES")
                 .unwrap_or_else(|| "en".to_string()),
+            signer: match crate::claims::load_or_create_key() {
+                Ok(s) => Some(s),
+                Err(e) => {
+                    warn!(target: "meta-feeder::enrich", error = %e,
+                          "no signing key; meta-core writes will fail");
+                    None
+                }
+            },
         }
     }
 }
@@ -218,7 +230,14 @@ impl Enricher {
             &self.cfg.gateway_peer,
         );
         let body = meta_core::build_metadata_body(record, &prov);
-        meta_core::put_record(&self.http, &self.cfg.meta_core_url, cid, &body).await
+        meta_core::put_record(&self.http, &self.cfg.meta_core_url, self.signer()?, cid, &body).await
+    }
+
+    fn signer(&self) -> anyhow::Result<&crate::claims::Signer> {
+        self.cfg
+            .signer
+            .as_ref()
+            .ok_or_else(|| anyhow::anyhow!("no signing key (METAMESH_SIGNING_KEY / _FILE)"))
     }
 
     /// Run the video enrichment pipeline for one resolved CID: filename-parser
@@ -240,14 +259,14 @@ impl Enricher {
                 Ok(()) => {
                     // Poll for the merged fields so tmdb gets the clean title.
                     if let Some(merged) = self
-                        .poll_until_field(cid, "originalTitle", FILENAME_PARSE_POLL_TIMEOUT)
+                        .poll_until_field(cid, "parsedTitle", FILENAME_PARSE_POLL_TIMEOUT)
                         .await
                     {
                         meta = merged;
                     } else {
                         debug!(
                             target: "meta-feeder::enrich",
-                            cid, "filename-parser produced no originalTitle within timeout; \
+                            cid, "filename-parser produced no parsedTitle within timeout; \
                                   handing tmdb the base fields"
                         );
                     }
@@ -324,7 +343,7 @@ impl Enricher {
 
         // Poll the primary for filename-parser's clean title, then tmdb it.
         let merged = self
-            .poll_until_field(&p.cid, "originalTitle", FILENAME_PARSE_POLL_TIMEOUT)
+            .poll_until_field(&p.cid, "parsedTitle", FILENAME_PARSE_POLL_TIMEOUT)
             .await
             .unwrap_or_else(|| p.base.clone());
 
@@ -355,9 +374,14 @@ impl Enricher {
             }
             // PUT is merge/upsert — this layers the show-level anchor onto each
             // file's record without disturbing its per-file fields.
-            if let Err(e) =
+            let res = match self.signer() {
-                meta_core::put_record(&self.http, &self.cfg.meta_core_url, &v.cid, &anchor).await
+                Ok(signer) => {
-            {
+                    meta_core::put_record(&self.http, &self.cfg.meta_core_url, signer, &v.cid, &anchor)
+                        .await
+                }
+                Err(e) => Err(e),
+            };
+            if let Err(e) = res {
                 warn!(target: "meta-feeder::enrich", cid = %v.cid, error = %e, "anchor fan PUT failed");
             }
         }

src/lib.rs

@@ -34,6 +34,8 @@ pub mod beacon;
 
 #[cfg(feature = "feeder")]
 pub mod budget;
+#[cfg(any(feature = "feeder", feature = "claims"))]
+pub mod claims;
 #[cfg(feature = "feeder")]
 pub mod cache;
 #[cfg(feature = "feeder")]
@@ -92,5 +94,9 @@ pub use serve::{
     HealthResponse, ManifestResponse, OutcomeDto, PluginManifest, QueryRequest, QueryResponse,
     RedeemsResponse,
 };
+#[cfg(any(feature = "feeder", feature = "claims"))]
+pub use claims::{ClaimValue, SignedClaim};
+#[cfg(feature = "claims")]
+pub use claims::{load_or_create_key, ClaimError, Signer};
 #[cfg(feature = "feeder")]
 pub use types::{ByteStream, DiscoveryId, DiscoveryRecord, GatewayError, Hash, PluginHealth};

src/meta_core.rs

@@ -12,10 +12,12 @@
 //! written by the feeder is indistinguishable from one the dispatcher wrote —
 //! the meta-share ingester, meta-watch, and ranking all behave the same.
 //!
-//! `PUT /api/metadata/{cid}` is merge/upsert (confirmed: meta-core
+//! Since meta-core v2.0.0 every write is a batch of **signed claims** to
-//! `SetMetadataFlat` sets only the fields in the payload, never deletes), so the
+//! `POST /api/claims` (spec `docs/implementation/metacore-claims-model.md`):
-//! feeder's base write and the enrichment plugins' later `PATCH /meta/{cid}`
+//! each field becomes one MMUR2 vote signed by this feeder's own key. Votes from
-//! merges accumulate on the same `/file/{cid}` hash.
+//! different writers never overwrite each other — meta-core merges them — so the
+//! feeder's base write and the enrichment plugins' later claims accumulate on
+//! the same cid.
 
 use std::collections::BTreeMap;
 use std::time::{SystemTime, UNIX_EPOCH};
@@ -23,6 +25,7 @@ use std::time::{SystemTime, UNIX_EPOCH};
 use serde::Deserialize;
 use tracing::warn;
 
+use crate::claims::{now_ms, ClaimValue, SignedClaim, Signer};
 use crate::plugin::{HashKind, HashOutcome};
 use crate::types::{DiscoveryRecord, Hash};
 
@@ -95,22 +98,76 @@ pub fn build_metadata_body(
     body
 }
 
-/// `PUT /api/metadata/{cid}` — write (merge/upsert) the record body into
+/// One per-claim verdict from `POST /api/claims`.
-/// meta-core. `base_url` is the meta-core root (e.g. `http://…-core:9000`).
+#[derive(Debug, Deserialize)]
-pub async fn put_record(
+pub struct ClaimStatus {
+    pub status: String,
+    #[serde(default)]
+    pub reason: Option<String>,
+}
+
+/// `POST /api/claims` — submit already-signed claims (e.g. relayed verbatim).
+/// Fails on a non-2xx answer or when any claim is refused as `bad_signature` /
+/// `bad_request`; `stale` and `unchanged` are normal outcomes.
+pub async fn post_claims(
     http: &reqwest::Client,
     base_url: &str,
-    cid: &str,
+    claims: &[SignedClaim],
-    body: &BTreeMap<String, String>,
+) -> anyhow::Result<Vec<ClaimStatus>> {
-) -> anyhow::Result<()> {
+    if claims.is_empty() {
-    let url = format!("{}/api/metadata/{}", base_url.trim_end_matches('/'), cid);
+        return Ok(Vec::new());
-    let resp = http.put(&url).json(body).send().await?;
+    }
+    let url = format!("{}/api/claims", base_url.trim_end_matches('/'));
+    let resp = http.post(&url).json(claims).send().await?;
     let status = resp.status();
     if !status.is_success() {
         let text = resp.text().await.unwrap_or_default();
-        anyhow::bail!("meta-core PUT {url} returned {status}: {text}");
+        anyhow::bail!("meta-core POST {url} returned {status}: {text}");
     }
-    Ok(())
+    let verdicts: Vec<ClaimStatus> = resp.json().await?;
+    if let Some((i, bad)) = verdicts
+        .iter()
+        .enumerate()
+        .find(|(_, v)| v.status == "bad_signature" || v.status == "bad_request")
+    {
+        anyhow::bail!(
+            "meta-core refused claim {} ({}): {} {}",
+            i,
+            claims.get(i).map(|c| c.key.as_str()).unwrap_or("?"),
+            bad.status,
+            bad.reason.as_deref().unwrap_or("")
+        );
+    }
+    Ok(verdicts)
+}
+
+/// Sign every field of `body` as a text claim on `cid` (all at "now") and
+/// submit them. The claims-model replacement for the v1 `PUT /api/metadata`.
+pub async fn put_record(
+    http: &reqwest::Client,
+    base_url: &str,
+    signer: &Signer,
+    cid: &str,
+    body: &BTreeMap<String, String>,
+) -> anyhow::Result<()> {
+    let claims = signer.sign_fields(cid, body, now_ms());
+    post_claims(http, base_url, &claims).await.map(|_| ())
+}
+
+/// Sign retractions of `keys` on `cid` (this signer's own votes only).
+pub async fn retract_keys(
+    http: &reqwest::Client,
+    base_url: &str,
+    signer: &Signer,
+    cid: &str,
+    keys: &[String],
+) -> anyhow::Result<()> {
+    let ts = now_ms();
+    let claims: Vec<SignedClaim> = keys
+        .iter()
+        .map(|k| signer.sign(cid, k, ClaimValue::Null, ts))
+        .collect();
+    post_claims(http, base_url, &claims).await.map(|_| ())
 }
 
 /// Shape of meta-core's `GET /meta/{cid}` response (`{ hashId, metadata }`).
@@ -162,27 +219,49 @@ pub struct FeederStore {
     http: reqwest::Client,
     meta_core_url: String,
     gateway_peer: String,
+    signer: Signer,
 }
 
 impl FeederStore {
-    pub fn new(http: reqwest::Client, meta_core_url: String, gateway_peer: String) -> Self {
+    pub fn new(
+        http: reqwest::Client,
+        meta_core_url: String,
+        gateway_peer: String,
+        signer: Signer,
+    ) -> Self {
         FeederStore {
             http,
             meta_core_url: meta_core_url.trim_end_matches('/').to_string(),
             gateway_peer,
+            signer,
         }
     }
 
-    /// Build from the feeder env. `None` when `META_CORE_URL` is unset (the
+    /// Build from the feeder env. `None` when `META_CORE_URL` is unset, or when
-    /// feeder then falls back to the legacy "return outcomes, gateway stores"
+    /// no signing key is configured (`METAMESH_SIGNING_KEY` /
-    /// path). `gateway_peer` ← `META_GATEWAY_PEER_ID` / `HOSTNAME`.
+    /// `METAMESH_SIGNING_KEY_FILE`) — the feeder then falls back to the legacy
+    /// "return outcomes, gateway stores" path. `gateway_peer` ←
+    /// `META_GATEWAY_PEER_ID` / `HOSTNAME`.
     pub fn from_env() -> Option<Self> {
         let meta_core_url = env_nonempty("META_CORE_URL")?;
+        let signer = match crate::claims::load_or_create_key() {
+            Ok(s) => s,
+            Err(e) => {
+                warn!(target: "meta-feeder::store", error = %e,
+                      "META_CORE_URL set but no signing key; not self-publishing");
+                return None;
+            }
+        };
         let gateway_peer = env_nonempty("META_GATEWAY_PEER_ID")
             .or_else(|| env_nonempty("HOSTNAME"))
             .unwrap_or_else(|| "gateway-feeder".to_string());
         let http = crate::common::build_http_client(30, "meta-feeder-store", None);
-        Some(Self::new(http, meta_core_url, gateway_peer))
+        Some(Self::new(http, meta_core_url, gateway_peer, signer))
+    }
+
+    /// The uid this store signs as.
+    pub fn signer(&self) -> &Signer {
+        &self.signer
     }
 
     pub fn meta_core_url(&self) -> &str {
@@ -262,7 +341,8 @@ impl FeederStore {
         }
     }
 
-    /// Metadata-only self-publish: `PUT /api/metadata/{cid}` with provenance.
+    /// Metadata-only self-publish: the record's fields (+ provenance) as signed
+    /// claims to `POST /api/claims`.
     async fn store_metadata_only(
         &self,
         upstream_id: &str,
@@ -272,7 +352,7 @@ impl FeederStore {
     ) -> anyhow::Result<()> {
         let prov = Provenance::now(upstream_id, record_id, &self.gateway_peer);
         let body = build_metadata_body(record, &prov);
-        put_record(&self.http, &self.meta_core_url, cid, &body).await
+        put_record(&self.http, &self.meta_core_url, &self.signer, cid, &body).await
     }
 }
 
@@ -305,6 +385,7 @@ mod tests {
                 ("title".into(), "Big Buck Bunny".into()),
                 ("cid_btih_v1_file".into(), "bafkPERFILE".into()),
             ]),
+            claims: Vec::new(),
         }
     }
 

src/query.rs

@@ -100,6 +100,10 @@ pub enum GatewaySearchEvent {
         record_id: String,
         set: BTreeMap<String, String>,
         remove: Vec<String>,
+        /// Signed form of the patch: `set` as text claims, `remove` as
+        /// retractions. Empty from a feeder (the gateway core signs).
+        #[serde(default)]
+        claims: Vec<crate::claims::SignedClaim>,
     },
     /// Retract a previously-emitted `Base` record entirely.
     Drop { record_id: String },

src/serve.rs

@@ -799,6 +799,7 @@ mod tests {
                 upstream_id: "stub".into(),
                 record_id: "1".into(),
                 fields: BTreeMap::new(),
+                claims: Vec::new(),
             };
             let events = vec![
                 GatewaySearchEvent::Base(rec),
@@ -806,6 +807,7 @@ mod tests {
                     record_id: "1".into(),
                     set: BTreeMap::from([("title".to_string(), "X".to_string())]),
                     remove: vec![],
+                    claims: vec![],
                 },
                 GatewaySearchEvent::Done,
             ];

src/types.rs

@@ -49,6 +49,13 @@ pub struct DiscoveryRecord {
     pub upstream_id: String,
     pub record_id: String,
     pub fields: BTreeMap<String, String>,
+    /// The record's MMUR2 claims (spec §10). Empty from a feeder that returns
+    /// plain `fields` (the gateway core signs those as itself); filled by a
+    /// self-publishing feeder or by the gateway before the record goes on the
+    /// wire. `#[serde(default)]` keeps older feeders' JSON `/query` answers
+    /// decoding.
+    #[serde(default)] // never skip_serializing_if: bincode is positional
+    pub claims: Vec<crate::claims::SignedClaim>,
 }
 
 /// In-process error returned by `FeederPlugin` methods.
@@ -102,6 +109,7 @@ mod tests {
                 ("title".to_string(), "AlphaFold".to_string()),
                 ("year".to_string(), "2021".to_string()),
             ]),
+            claims: Vec::new(),
         };
         let j = serde_json::to_string(&r).expect("serialize");
         let back: DiscoveryRecord = serde_json::from_str(&j).expect("deserialize");

tests/claim-vectors.json

@@ -0,0 +1,93 @@
+{
+  "_comment": "MMUR2 golden vectors. Canonical copy: meta-core internal/claim/testdata. Do not edit by hand; see claim_test.go.",
+  "privateKeyHex": "0101010101010101010101010101010101010101010101010101010101010101",
+  "uid": "zvYNYVRtXSSDCi1rZtPP3ieuoh8cG5AscesGPYESa4VpJ",
+  "vectors": [
+    {
+      "name": "text",
+      "cid": "bafkreih5kapbjzq",
+      "uid": "zvYNYVRtXSSDCi1rZtPP3ieuoh8cG5AscesGPYESa4VpJ",
+      "key": "title",
+      "value": "The Matrix",
+      "ts": 1793001234567,
+      "signedBytesHex": "4d4d5552320a85706261666b72656968356b6170626a7a71782d7a76594e5956527458535344436931725a745050336965756f683863473541736365734750594553613456704a657469746c656a546865204d61747269781b000001a17733a087",
+      "sigHex": "3ecac653f63cfc981564b5a5cc0db0459f2b4f19b810b6391d8f487216da0f3d2e560a2b61f4a81e320287cde753e1990d7949f4f518127f6505b8fb698ee8a8"
+    },
+    {
+      "name": "empty-text",
+      "cid": "bafkreih5kapbjzq",
+      "uid": "zvYNYVRtXSSDCi1rZtPP3ieuoh8cG5AscesGPYESa4VpJ",
+      "key": "title",
+      "value": "",
+      "ts": 1,
+      "signedBytesHex": "4d4d5552320a85706261666b72656968356b6170626a7a71782d7a76594e5956527458535344436931725a745050336965756f683863473541736365734750594553613456704a657469746c656001",
+      "sigHex": "6eeb9ace8afe3987006c166eb0ec564b71e23d6a1c6211fdd55e8b4779c12dbb4f38c443faa3255c2ce7c6592e9d024e4ea57b5fa23446d1d4df647947e37642"
+    },
+    {
+      "name": "unicode",
+      "cid": "bafkreih5kapbjzq",
+      "uid": "zvYNYVRtXSSDCi1rZtPP3ieuoh8cG5AscesGPYESa4VpJ",
+      "key": "titles/jpn/攻殻機動隊",
+      "value": "true",
+      "ts": 1793001234567,
+      "signedBytesHex": "4d4d5552320a85706261666b72656968356b6170626a7a71782d7a76594e5956527458535344436931725a745050336965756f683863473541736365734750594553613456704a781a7469746c65732f6a706e2fe694bbe6aebbe6a99fe58b95e99a8a64747275651b000001a17733a087",
+      "sigHex": "64ec6342c598782df278b49636a34da4f4c009423a584454a3284efad5426aa517d83873b09a4fdd3fd32a5e9a5fef0880126edd11db773045caeb6e634bc207"
+    },
+    {
+      "name": "keyset-member",
+      "cid": "bagacbabaec7v3",
+      "uid": "zvYNYVRtXSSDCi1rZtPP3ieuoh8cG5AscesGPYESa4VpJ",
+      "key": "cids/bafkreih5kapbjzq",
+      "value": "true",
+      "ts": 23,
+      "signedBytesHex": "4d4d5552320a856e6261676163626162616563377633782d7a76594e5956527458535344436931725a745050336965756f683863473541736365734750594553613456704a75636964732f6261666b72656968356b6170626a7a71647472756517",
+      "sigHex": "8f707847895ccb522f1507dbab23330bd2c567d6fd1882df3bfae65bef6601024832f0b181146dcfb089aae91f5beac47da970373ab14370c4ac41410f3bf761"
+    },
+    {
+      "name": "bytes",
+      "cid": "bafkreih5kapbjzq",
+      "uid": "zvYNYVRtXSSDCi1rZtPP3ieuoh8cG5AscesGPYESa4VpJ",
+      "key": "seek",
+      "value": null,
+      "valueBytesHex": "00ff10ab",
+      "ts": 24,
+      "signedBytesHex": "4d4d5552320a85706261666b72656968356b6170626a7a71782d7a76594e5956527458535344436931725a745050336965756f683863473541736365734750594553613456704a647365656b4400ff10ab1818",
+      "sigHex": "09671b27c03edd510029ec550b35e95e3900dd37a5d688ea04c3f0409979c7236bc4a1b5fa9d1b76265da85df24693a51f0ced528a6171c90a70b92db9f246e4"
+    },
+    {
+      "name": "retraction",
+      "cid": "bafkreih5kapbjzq",
+      "uid": "zvYNYVRtXSSDCi1rZtPP3ieuoh8cG5AscesGPYESa4VpJ",
+      "key": "genres/Drama",
+      "value": null,
+      "ts": 255,
+      "signedBytesHex": "4d4d5552320a85706261666b72656968356b6170626a7a71782d7a76594e5956527458535344436931725a745050336965756f683863473541736365734750594553613456704a6c67656e7265732f4472616d61f618ff",
+      "sigHex": "d0c29d8edac4b78005eaf895cd9d534cb080b22ba9f7e79a5abf4d9bd906dc494464a2b388653452bca16e351132a9a92370953fa047e693459e55b7965449ac"
+    },
+    {
+      "name": "long-value",
+      "cid": "bafkreih5kapbjzq",
+      "uid": "zvYNYVRtXSSDCi1rZtPP3ieuoh8cG5AscesGPYESa4VpJ",
+      "key": "plot/eng",
+      "value": "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+      "ts": 65536,
+      "signedBytesHex": "4d4d5552320a85706261666b72656968356b6170626a7a71782d7a76594e5956527458535344436931725a745050336965756f683863473541736365734750594553613456704a68706c6f742f656e6779012c6161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161616161611a00010000",
+      "sigHex": "383b2e40f913eb5240e1eae2cfa392f967321d3701623c2b3df344984686d888198bce1c78847d1898b35f991ec3465c382c45e03b9a77f2ae7d1fd740391dd2"
+    },
+    {
+      "name": "ts-64bit",
+      "cid": "bafkreih5kapbjzq",
+      "uid": "zvYNYVRtXSSDCi1rZtPP3ieuoh8cG5AscesGPYESa4VpJ",
+      "key": "year",
+      "value": "1999",
+      "ts": 1099511627776,
+      "signedBytesHex": "4d4d5552320a85706261666b72656968356b6170626a7a71782d7a76594e5956527458535344436931725a745050336965756f683863473541736365734750594553613456704a647965617264313939391b0000010000000000",
+      "sigHex": "2b9b42ef4ebd7fc8d3ca0a514679ca4104f2e627da3a84c7b9664b27ebbdf73946cc37a04e4ea15dbed23a0e48e8797c92fcba5598b012305a314bf776398e0d"
+    }
+  ],
+  "highS": {
+    "note": "same claim as `vector`, S replaced by n-S: valid ECDSA, but MMUR2 verifiers must refuse it",
+    "vector": "text",
+    "sigHex": "3ecac653f63cfc981564b5a5cc0db0459f2b4f19b810b6391d8f487216da0f3dd1a9f5d49e0b57e1cdfd783218ac1e65ad3592f1ba308dbc5acca59166a75899"
+  }
+}