lib: Add membership and all-in-one cert, replace addresses with ids

Cargo.toml

@@ -10,3 +10,8 @@ path = "src/main.rs"
 [dependencies]
 ed25519-dalek = "2.1.1"
 rand = "0.8.5"
+rs_merkle = "1.4.2"
+sha2 = "0.10.8"
+
+[dev-dependencies]
+once_cell = "1.19.0"

src/lib.rs

@@ -1,10 +1,11 @@
-use dalek::Verifier;
-use ed25519_dalek as dalek;
-use rand::prelude as rand;
+use std::collections::HashMap;
 
-pub type Address = [u8; 32];
-pub type Signature = [u8; 64];
-pub type Salt = [u8; 32];
+use ed25519_dalek as dalek;
+use ed25519_dalek::Verifier;
+use rand::prelude::random;
+use rs_merkle::algorithms::Sha256 as Sha256Algorithm; // Imports from sha2 crate
+use rs_merkle::{MerkleProof, MerkleTree};
+use sha2::{Digest, Sha256};
 
 /// TODO: Use hashes instead of public addresses.
 /// TODO: Don't forget document endiannes.
@@ -16,10 +17,12 @@ pub type Salt = [u8; 32];
 /// full crypto-conditions but better not to complicate things too
 /// much.
 
+pub type Address = [u8; 32];
+
 #[derive(Copy, Clone, PartialEq, Debug)]
 pub struct Obligation {
-    pub from: Address,
-    pub to: Address,
+    pub from: PseudoAnonID,
+    pub to: PseudoAnonID,
     pub value: u32,
 }
 
@@ -29,14 +32,16 @@ impl Obligation {
     }
 }
 
+pub type Signature = [u8; 64];
+pub type Salt = [u8; 32];
+
 #[derive(Copy, Clone)]
-pub struct Cert {
+pub struct AuthCert {
     pub subject: Obligation,
     pub signature: Signature,
-    pub salt: Salt,
 }
 
-impl Cert {
+impl AuthCert {
     /// TODO: add optional salt argument
     pub fn new(sub: Obligation, sig: Signature) -> Result<Self, &'static str> {
         match dalek::VerifyingKey::from_bytes(&sub.from)
@@ -46,17 +51,138 @@ impl Cert {
             Ok(_) => Ok(Self {
                 subject: sub,
                 signature: sig,
-                salt: rand::random(),
             }),
             Err(_) => Err("Invalid signature"),
         }
     }
 }
 
+pub type PseudoAnonID = [u8; 32];
+
+fn pseudo_anon_id(a: Address) -> PseudoAnonID {
+    let mut h = Sha256::new();
+    h.update(a);
+    let res: PseudoAnonID = h.finalize().into();
+    res
+}
+
+pub struct Members {
+    data: MerkleTree<Sha256Algorithm>,
+    indicies: HashMap<PseudoAnonID, usize>,
+}
+
+pub type MembershipProof = MerkleProof<Sha256Algorithm>;
+
+impl Members {
+    pub fn add(mut self, m: Address) {
+        self.data.insert(m).commit()
+    }
+    pub fn proof(&self, members: &[PseudoAnonID]) -> MembershipProof {
+        self.data.proof(
+            &members
+                .iter()
+                .map(|x| *self.indicies.get(x).unwrap())
+                .collect::<Vec<_>>(),
+        )
+    }
+}
+
+pub struct Cert {
+    pub subject: Obligation,
+    pub authenticity: AuthCert,
+    pub membership: MembershipProof,
+    pub salt: Salt,
+    pub hash: Vec<u8>,
+}
+
+impl Cert {
+    pub fn new(sub: Obligation, auth: AuthCert, mem: MembershipProof) -> Self {
+        let mut h = Sha256::new();
+        let salt: Salt = random();
+        h.update(sub.serialize());
+        h.update(salt);
+        Self {
+            subject: sub,
+            authenticity: auth,
+            membership: mem,
+            salt: salt,
+            hash: h.finalize().to_vec(),
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
-    use crate::{Cert, Obligation};
-    use ed25519_dalek::{Signer, SigningKey};
+    use super::*;
+    use ed25519_dalek::Signer;
+    use once_cell::sync::Lazy;
+    use rand::seq::IteratorRandom;
+
+    fn sk_gen() -> (dalek::SigningKey, [u8; dalek::SECRET_KEY_LENGTH], Address) {
+        let skobj = dalek::SigningKey::from_bytes(&random());
+        (
+            skobj.clone(),
+            skobj.to_bytes(),
+            skobj.verifying_key().to_bytes(),
+        )
+    }
+
+    #[allow(dead_code)]
+    struct ObligationFixture {
+        o: Obligation,
+        f: dalek::SigningKey,
+        t: dalek::SigningKey,
+        fpk: [u8; 32],
+        tpk: [u8; 32],
+        fsk: [u8; 32],
+        tsk: [u8; 32],
+    }
+
+    static OFIX: Lazy<ObligationFixture> = Lazy::new(|| {
+        let (f, fsk, fpk) = sk_gen();
+        let (t, tsk, tpk) = sk_gen();
+        ObligationFixture {
+            o: Obligation {
+                from: fpk,
+                to: tpk,
+                value: 1000,
+            },
+            f: f,
+            t: t,
+            fpk: fpk,
+            tpk: tpk,
+            fsk: fsk,
+            tsk: tsk,
+        }
+    });
+
+    #[allow(dead_code)]
+    struct AddrMeta {
+        sk: dalek::SigningKey,
+        id: PseudoAnonID,
+    }
+
+    static ADDRESSES: Lazy<HashMap<Address, AddrMeta>> = Lazy::new(|| {
+        let mut v: HashMap<Address, AddrMeta> = HashMap::new();
+        for _i in 0..10 {
+            let (obj, _, pk) = sk_gen();
+            v.insert(
+                pk,
+                AddrMeta {
+                    sk: obj,
+                    id: pseudo_anon_id(pk),
+                },
+            );
+        }
+        v
+    });
+
+    static MEMBERS: Lazy<Members> = Lazy::new(|| Members {
+        data: MerkleTree::<Sha256Algorithm>::from_leaves(
+            &ADDRESSES.keys().map(|x| x.clone()).collect::<Vec<_>>(),
+        ),
+        indicies: HashMap::from_iter(ADDRESSES.keys().enumerate().map(|(i, x)| (x.clone(), i))),
+    });
 
     #[test]
     fn serialize_obligation() {
@@ -76,27 +202,44 @@ mod tests {
     }
 
     #[test]
-    fn cert_new() {
-        let sk_gen = || {
-            let skobj = SigningKey::from_bytes(&rand::random());
-            (
-                skobj.clone(),
-                skobj.to_bytes(),
-                skobj.verifying_key().to_bytes(),
-            )
-        };
-        let (f, _, fpk) = sk_gen();
-        let (_, _, tpk) = sk_gen();
-        let sub = Obligation {
-            from: fpk,
-            to: tpk,
+    fn authenticity_cert_new() {
+        let sig = OFIX.f.sign(&OFIX.o.serialize()[..]).to_bytes();
+        let cert = AuthCert::new(OFIX.o, sig);
+        assert!(cert.is_ok());
+        assert_eq!(cert.unwrap().subject, OFIX.o);
+        assert_eq!(cert.unwrap().signature, sig);
+        assert!(AuthCert::new(OFIX.o, [0; 64]).is_err());
+    }
+
+    #[test]
+    fn membership_cert_new() {
+        fn rand_member() -> PseudoAnonID {
+            assert_ne!(ADDRESSES.len(), 0);
+            *MEMBERS
+                .indicies
+                .keys()
+                .choose(&mut rand::thread_rng())
+                .unwrap()
+        }
+        let o = Obligation {
+            from: rand_member(),
+            to: rand_member(),
             value: 1000,
         };
-        let sig = f.sign(&sub.serialize()[..]).to_bytes();
-        let cert = Cert::new(sub, sig);
-        assert!(cert.is_ok());
-        assert_eq!(cert.unwrap().subject, sub);
-        assert_eq!(cert.unwrap().signature, sig);
-        assert!(Cert::new(sub, [0; 64]).is_err());
+        let _c = Cert::new(
+            o,
+            AuthCert::new(
+                o,
+                ADDRESSES
+                    .get(&o.from)
+                    .unwrap()
+                    .sk
+                    .sign(&o.serialize())
+                    .into(),
+            )
+            .expect("Auth failed"),
+            MEMBERS.proof(&[o.from, o.to]),
+        );
+        assert!(true)
     }
 }