M poseidon-cipher/Cargo.toml → poseidon-cipher/Cargo.toml

@@ -4,10 +4,8 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
-plonky2 = { git = "https://github.com/0xPARC/plonky2.git", rev = "109d517d09c210ae4c2cee381d3e3fbc04aa3812" }
-anyhow = "1.0.56"
-# plonky2 = { workspace = true }
-# anyhow = { workspace = true }
+plonky2 = { workspace = true }
+anyhow = { workspace = true }
 num = { version = "0.4.3", features = ["num-bigint"] }
 pod2 = { git = "https://github.com/0xPARC/pod2", rev = "cdf227e3530247e07e375daed007cae7d443b4ae" } # for ecgfp5
 num-bigint = { version = "0.4.6", features = ["rand"] }

M poseidon-cipher/src/circuit.rs → poseidon-cipher/src/circuit.rs

@@ -1,4 +1,7 @@
 //! For LICENSE check out https://github.com/0xPARC/plonky2-crypto-gadgets/blob/main/LICENSE
+//!
+//! Implements the Plonky2 circuits for Poseidon encryption as described at
+//! https://drive.google.com/file/d/1EVrP3DzoGbmzkRmYnyEDcIQcXVU7GlOd/view .
 
 use std::array;
 
@@ -7,7 +10,7 @@ use plonky2::{
     field::{
         extension::{FieldExtension, quintic::QuinticExtension},
         goldilocks_field::GoldilocksField as F,
-        types::Field,
+        types::{Field, Field64},
     },
     hash::poseidon::PoseidonHash,
     iop::{
@@ -35,7 +38,7 @@ [(); L + 1]:,
 {
     ks: PointTarget,
     m: [FqT; L],
-    nonce: Target,
+    nonce: [Target; 2],
     ct: [FqT; L + 1],
 }
 
@@ -45,17 +48,18 @@ [(); L + 1]:,
 {
     pub fn build(builder: &mut CircuitBuilder<F, D>) -> Self {
         assert!(L.is_multiple_of(3));
+        assert!(L < F::ORDER as usize);
         let fqt_zero = const_fqt_zero(builder);
 
         // add targets
         let ks: PointTarget = builder.add_virtual_point_target();
         let m: [FqT; L] = array::from_fn(|_| builder.add_virtual_nnf_target());
-        let nonce: Target = builder.add_virtual_target();
+        let nonce: [Target; 2] = builder.add_virtual_target_arr::<2>();
         let mut ct: [FqT; L + 1] = array::from_fn(|_| fqt_zero.clone());
 
         // build the circuit logic
         let f_zero = builder.constant(F::ZERO);
-        let n = FqT::new([nonce, f_zero, f_zero, f_zero, f_zero]);
+        let n = FqT::new([nonce[0], nonce[1], f_zero, f_zero, f_zero]);
         let two128: Fq = two_128();
         let l_two128: Fq = Fq::from_basefield_array([
             F::from_canonical_u64(L as u64),
@@ -93,7 +97,7 @@ &self,
         pw: &mut PartialWitness<F>,
         ks: Point,
         m: &[Fq],
-        nonce: F,
+        nonce: [F; 2],
         ct: &[Fq],
     ) -> Result<()> {
         assert_eq!(m.len(), L);
@@ -106,7 +110,7 @@ for j in 0..5 {
                 pw.set_target(self.m[i].components[j], m[i].0[j])?;
             }
         }
-        pw.set_target(self.nonce, nonce)?;
+        pw.set_target_arr(&self.nonce, &nonce)?;
         #[allow(clippy::needless_range_loop)]
         for i in 0..L + 1 {
             for j in 0..5 {
@@ -159,7 +163,7 @@ const L: usize = 129; // (multiple of 3)
 
         let (_k, K) = crate::new_key();
         let ks = crate::expanded_key(K);
-        let nonce = F::rand();
+        let nonce: [F; 2] = [F::rand(), F::rand()];
         let msg: Vec<Fq> = (0..L).map(|_| Fq::sample(&mut rng)).collect();
         let l = msg.len();
 

M poseidon-cipher/src/lib.rs → poseidon-cipher/src/lib.rs

@@ -1,4 +1,7 @@
 //! For LICENSE check out https://github.com/0xPARC/plonky2-crypto-gadgets/blob/main/LICENSE
+//!
+//! Implements Poseidon encryption as described at
+//! https://drive.google.com/file/d/1EVrP3DzoGbmzkRmYnyEDcIQcXVU7GlOd/view .
 
 #![allow(incomplete_features)]
 #![feature(generic_const_exprs)]
@@ -48,13 +51,13 @@ // dbg!(&two128);
     two128
 }
 
-pub fn encrypt(ks: Point, msg: &[Fq], nonce: F) -> Vec<Fq> {
-    // pad m
-    let mut m = msg.to_vec();
+pub fn encrypt(ks: Point, msg: &[Fq], nonce: [F; 2]) -> Vec<Fq> {
+    let mut m = msg.to_vec(); // pad m
     m.resize(m.len().next_multiple_of(3), Fq::ZERO);
 
     let l = Fq::from(F::from_canonical_u64(msg.len() as u64));
-    let n = Fq::from(nonce);
+    let nonce_5: [F; 5] = [nonce[0], nonce[1], F::ZERO, F::ZERO, F::ZERO];
+    let n = Fq::from_basefield_array(nonce_5);
     let nl128: Fq = n + l * two_128();
     let mut s: [Fq; 4] = [Fq::ZERO, ks.x, ks.u, nl128];
 
@@ -77,9 +80,10 @@ ct[m.len()] = s[1];
     ct
 }
 
-pub fn decrypt(ks: Point, ct: &[Fq], nonce: F, l: usize) -> Vec<Fq> {
+pub fn decrypt(ks: Point, ct: &[Fq], nonce: [F; 2], l: usize) -> Vec<Fq> {
     let l_fq = Fq::from(F::from_canonical_u64(l as u64));
-    let n = Fq::from(nonce);
+    let nonce_5: [F; 5] = [nonce[0], nonce[1], F::ZERO, F::ZERO, F::ZERO];
+    let n = Fq::from_basefield_array(nonce_5);
     let nl128: Fq = n + l_fq * two_128();
     let mut s: [Fq; 4] = [Fq::ZERO, ks.x, ks.u, nl128];
 
@@ -113,6 +117,7 @@ }
 
 fn hash_state(s: [Fq; 4]) -> [Fq; 4] {
     let elems: [F; 4 * 5] = array::from_fn(|i| s[i / 5].0[i % 5]);
+    // Note: here we're using plonky2's normal poseidon, not duplex-sponge
     let h = hash_n_to_m_no_pad::<F, PoseidonPermutation<_>>(&elems, 4 * 5);
     array::from_fn(|i| Fq::from_basefield_array(array::from_fn::<_, 5, _>(|j| h[j + 5 * i])))
 }
@@ -140,7 +145,7 @@ let mut rng = rand::thread_rng();
 
         let (_k, K) = new_key();
         let ks = expanded_key(K);
-        let nonce = F::rand();
+        let nonce: [F; 2] = [F::rand(), F::rand()];
         let msg: Vec<Fq> = (0..msg_len).map(|_| Fq::sample(&mut rng)).collect();
         let l = msg.len();