garbled separating sender and eval

src/garble_classic.rs

@@ -38,24 +38,49 @@ fn decrypt(key_a: [u8; 16], key_b: [u8; 16], encrypted: [u8; 32]) -> Option<[u8;
 struct Wire {
     sym: Option<String>,
     keys: [[u8; 16]; 2],
-    secret: bool,
+    evaluator: bool,
 }
 
 #[derive(Clone, Debug)]
-struct Circuit {
-    left: Box<CircOption>,
-    right: Box<CircOption>,
+struct Gate {
+    left: Box<Circuit>,
+    right: Box<Circuit>,
     out: Wire,
     table: [[[u8; 32]; 2]; 2],
     sym: String,
 }
 
 #[derive(Clone, Debug)]
-enum CircOption {
-    Circuit(Circuit),
+enum Circuit {
+    Gate(Gate),
     Wire(Wire),
 }
 
+#[derive(Clone, Debug)]
+struct HiddenWire {
+    sym: Option<String>,
+}
+
+#[derive(Clone, Debug)]
+struct HiddenGate {
+    left: Box<HiddenCircuit>,
+    right: Box<HiddenCircuit>,
+    table: [[[u8; 32]; 2]; 2],
+    sym: String,
+}
+
+#[derive(Clone, Debug)]
+enum HiddenCircuit {
+    Gate(HiddenGate),
+    Wire(HiddenWire),
+}
+
+#[derive(Clone, Debug)]
+struct FullyHiddenCircuit {
+    table: [[u8; 32]; 2],
+    circuit: HiddenCircuit,
+}
+
 impl Display for Wire {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match &self.sym {
@@ -65,39 +90,39 @@ impl Display for Wire {
     }
 }
 
-impl Display for CircOption {
+impl Display for Circuit {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
-            CircOption::Wire(w) => write!(f, "{}", w),
-            CircOption::Circuit(c) => write!(f, "{}", c),
+            Circuit::Wire(w) => write!(f, "{}", w),
+            Circuit::Gate(c) => write!(f, "{}", c),
         }
     }
 }
 
-impl Display for Circuit {
+impl Display for Gate {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         write!(f, "{} {} {}", self.left, self.sym, self.right)
     }
 }
 
 impl Wire {
-    fn new_rng(sym: String, secret: bool, rng: &mut (impl RngCore + CryptoRng)) -> Self {
+    fn new_rng(sym: String, evaluator: bool, rng: &mut (impl RngCore + CryptoRng)) -> Self {
         let mut keys = [[0; 16]; 2];
         rng.fill_bytes(&mut keys[0]);
         rng.fill_bytes(&mut keys[1]);
         Self {
             sym: Some(sym),
             keys,
-            secret,
+            evaluator,
         }
     }
 
-    fn new(sym: String, secret: bool) -> Self {
-        Self::new_rng(sym, secret, &mut OsRng)
+    fn new(sym: String, evaluator: bool) -> Self {
+        Self::new_rng(sym, evaluator, &mut OsRng)
     }
 
-    fn to_circ(&self) -> CircOption {
-        CircOption::Wire(self.clone())
+    fn to_circ(&self) -> Circuit {
+        Circuit::Wire(self.clone())
     }
 
     fn empty(rng: &mut (impl RngCore + CryptoRng)) -> Self {
@@ -107,27 +132,27 @@ impl Wire {
         Self {
             sym: None,
             keys,
-            secret: false,
+            evaluator: false,
         }
     }
 }
 
-impl Circuit {
+impl Gate {
     fn new(
-        left: CircOption,
-        right: CircOption,
+        left: Circuit,
+        right: Circuit,
         value: [[bool; 2]; 2],
         sym: String,
         rng: &mut (impl RngCore + CryptoRng),
     ) -> Self {
         let linp_keys = match left {
-            CircOption::Wire(ref w) => w.keys,
-            CircOption::Circuit(ref c) => c.out.keys,
+            Circuit::Wire(ref w) => w.keys,
+            Circuit::Gate(ref c) => c.out.keys,
         };
 
         let rinp_keys = match right {
-            CircOption::Wire(ref w) => w.keys,
-            CircOption::Circuit(ref c) => c.out.keys,
+            Circuit::Wire(ref w) => w.keys,
+            Circuit::Gate(ref c) => c.out.keys,
         };
 
         let out = Wire::empty(rng);
@@ -157,15 +182,15 @@ impl Circuit {
         }
     }
 
-    fn to_circ(&self) -> CircOption {
-        CircOption::Circuit(self.clone())
+    fn to_circ(&self) -> Circuit {
+        Circuit::Gate(self.clone())
     }
 }
 
-impl CircOption {
+impl Circuit {
     fn evaluate_re(&self, vals: HashMap<String, bool>) -> [u8; 16] {
         match self {
-            CircOption::Circuit(c) => {
+            Circuit::Gate(c) => {
                 let lv = c.left.evaluate_re(vals.clone());
                 let rv = c.right.evaluate_re(vals);
                 let mut out = [0; 16];
@@ -178,8 +203,8 @@ impl CircOption {
                 }
                 out
             }
-            CircOption::Wire(w) => match &w.sym {
-                // Errr OT? hello?
+            Circuit::Wire(w) => match &w.sym {
+                // No OT
                 Some(c) => w.keys[(vals[c]) as usize],
                 None => panic!("This should not happen."),
             },
@@ -190,7 +215,7 @@ impl CircOption {
         let out_label = self.evaluate_re(vals);
 
         match self {
-            CircOption::Circuit(c) => {
+            Circuit::Gate(c) => {
                 if out_label == c.out.keys[0] {
                     false
                 } else if out_label == c.out.keys[1] {
@@ -199,7 +224,7 @@ impl CircOption {
                     panic!("Error!");
                 }
             }
-            CircOption::Wire(w) => {
+            Circuit::Wire(w) => {
                 if out_label == w.keys[0] {
                     false
                 } else if out_label == w.keys[1] {
@@ -210,13 +235,111 @@ impl CircOption {
             }
         }
     }
+
+    pub fn to_hidden(
+        &self,
+    ) -> (
+        FullyHiddenCircuit,
+        HashMap<String, [[u8; 16]; 2]>,
+        HashMap<String, [[u8; 16]; 2]>,
+    ) {
+        let (circ, map1, map2) = self.to_hidden_re();
+        match self {
+            Circuit::Gate(c) => {
+                let out_keys = c.out.keys;
+                let mut table = [[0; 32]; 2];
+
+                let i = OsRng.gen::<bool>() as usize;
+
+                for bit in [i, 1 - i] {
+                    let enc = encrypt(out_keys[bit], [0; 16], [bit as u8; 16]);
+                    table[bit] = enc;
+                }
+                (
+                    FullyHiddenCircuit {
+                        table,
+                        circuit: circ,
+                    },
+                    map1,
+                    map2,
+                )
+            }
+            Circuit::Wire(w) => {
+                let out_keys = w.keys;
+                let mut table = [[0; 32]; 2];
+                let i = OsRng.gen::<bool>() as usize;
+                for bit in [i, 1 - i] {
+                    let enc = encrypt(out_keys[bit], [0; 16], [bit as u8; 16]);
+                    table[bit] = enc;
+                }
+                (
+                    FullyHiddenCircuit {
+                        table,
+                        circuit: circ,
+                    },
+                    map1,
+                    map2,
+                )
+            }
+        }
     }
 
-impl BitAnd for CircOption {
-    type Output = CircOption;
+    fn to_hidden_re(
+        &self,
+    ) -> (
+        HiddenCircuit,
+        HashMap<String, [[u8; 16]; 2]>,
+        HashMap<String, [[u8; 16]; 2]>,
+    ) {
+        match self {
+            Circuit::Gate(c) => {
+                let (c1, sender1, eval1) = c.left.to_hidden_re();
+                let (c2, sender2, eval2) = c.right.to_hidden_re();
+                (
+                    HiddenCircuit::Gate(HiddenGate {
+                        left: Box::new(c1),
+                        right: Box::new(c2),
+                        table: c.table,
+                        sym: c.sym.clone(),
+                    }),
+                    sender1.into_iter().chain(sender2).collect(),
+                    eval1.into_iter().chain(eval2).collect(),
+                )
+            }
+            Circuit::Wire(w) => {
+                let out = match w.sym.clone() {
+                    Some(s) => s,
+                    None => panic!("Need wire description."),
+                };
+                if w.evaluator {
+                    let sender = HashMap::new();
+                    let mut eval = HashMap::new();
+                    eval.insert(out, w.keys);
+                    (
+                        HiddenCircuit::Wire(HiddenWire { sym: w.sym.clone() }),
+                        sender,
+                        eval,
+                    )
+                } else {
+                    let mut sender = HashMap::new();
+                    let eval = HashMap::new();
+                    sender.insert(out, w.keys);
+                    (
+                        HiddenCircuit::Wire(HiddenWire { sym: w.sym.clone() }),
+                        sender,
+                        eval,
+                    )
+                }
+            }
+        }
+    }
+}
+
+impl BitAnd for Circuit {
+    type Output = Circuit;
 
     fn bitand(self, rhs: Self) -> Self::Output {
-        CircOption::Circuit(Circuit::new(
+        Circuit::Gate(Gate::new(
             self,
             rhs,
             [[false, false], [false, true]],
@@ -226,11 +349,11 @@ impl BitAnd for CircOption {
     }
 }
 
-impl BitOr for CircOption {
-    type Output = CircOption;
+impl BitOr for Circuit {
+    type Output = Circuit;
 
     fn bitor(self, rhs: Self) -> Self::Output {
-        CircOption::Circuit(Circuit::new(
+        Circuit::Gate(Gate::new(
             self,
             rhs,
             [[false, true], [true, true]],
@@ -240,11 +363,11 @@ impl BitOr for CircOption {
     }
 }
 
-impl BitXor for CircOption {
-    type Output = CircOption;
+impl BitXor for Circuit {
+    type Output = Circuit;
 
     fn bitxor(self, rhs: Self) -> Self::Output {
-        CircOption::Circuit(Circuit::new(
+        Circuit::Gate(Gate::new(
             self,
             rhs,
             [[false, true], [true, false]],
@@ -254,11 +377,95 @@ impl BitXor for CircOption {
     }
 }
 
+impl From<Wire> for HiddenWire {
+    fn from(value: Wire) -> Self {
+        Self { sym: value.sym }
+    }
+}
+
+impl From<Gate> for HiddenGate {
+    fn from(value: Gate) -> Self {
+        Self {
+            left: Box::new((*value.left).into()),
+            right: Box::new((*value.right).into()),
+            table: value.table,
+            sym: value.sym,
+        }
+    }
+}
+
+impl From<Circuit> for HiddenCircuit {
+    fn from(value: Circuit) -> Self {
+        match value {
+            Circuit::Gate(c) => Self::Gate(c.into()),
+            Circuit::Wire(w) => Self::Wire(w.into()),
+        }
+    }
+}
+
+impl HiddenCircuit {
+    fn evaluate_re(&self, vals: HashMap<String, [u8; 16]>) -> [u8; 16] {
+        match self {
+            HiddenCircuit::Gate(c) => {
+                let lv = c.left.evaluate_re(vals.clone());
+                let rv = c.right.evaluate_re(vals);
+                let mut out = [0; 16];
+                for i in [0, 1] {
+                    for j in [0, 1] {
+                        if let Some(x) = decrypt(lv, rv, c.table[i][j]) {
+                            out = x;
+                        }
+                    }
+                }
+                out
+            }
+            HiddenCircuit::Wire(w) => match &w.sym {
+                Some(c) => vals[c],
+                None => panic!("This should not happen."),
+            },
+        }
+    }
+}
+
+impl FullyHiddenCircuit {
+    pub fn evaluate(
+        &self,
+        sender: HashMap<String, [u8; 16]>,
+        eval: HashMap<String, [u8; 16]>,
+    ) -> bool {
+        let out_label = self
+            .circuit
+            .evaluate_re(sender.into_iter().chain(eval).collect());
+
+        let mut out = false;
+        for i in [0, 1] {
+            if let Some(x) = decrypt(out_label, [0; 16], self.table[i]) {
+                out = x[0] != 0;
+            }
+        }
+        out
+    }
+}
+
+pub fn map_values_to_keys(
+    keys: HashMap<String, [[u8; 16]; 2]>,
+    values: Vec<(String, bool)>,
+) -> HashMap<String, [u8; 16]> {
+    let mut ret = HashMap::new();
+    for i in values {
+        match keys.get(&i.0) {
+            Some(v) => ret.insert(i.0, v[i.1 as usize]),
+            None => continue,
+        };
+    }
+    ret
+}
+
 #[cfg(test)]
 mod test {
 
     use crate::garble_classic::Wire;
-    use crate::garble_classic::{decrypt, encrypt};
+    use crate::garble_classic::{decrypt, encrypt, map_values_to_keys};
     use std::collections::HashMap;
 
     #[test]
@@ -268,7 +475,7 @@ mod test {
     }
 
     #[test]
-    fn circuit() {
+    fn public_circuit() {
         let a = Wire::new("a".to_string(), true).to_circ();
         let b = Wire::new("b".to_string(), false).to_circ();
         let c = Wire::new("c".to_string(), false).to_circ();
@@ -278,7 +485,29 @@ mod test {
         h.insert("a".to_string(), false);
         h.insert("b".to_string(), false);
         h.insert("c".to_string(), true);
+
         let out = circ.evaluate(h);
         assert!(out == false);
     }
+
+    #[test]
+    fn garbled_circuit() {
+        let a = Wire::new("a".to_string(), true).to_circ();
+        let b = Wire::new("b".to_string(), false).to_circ();
+        let c = Wire::new("c".to_string(), false).to_circ();
+        let circ = (a | b) & c;
+
+        let (hidden_circ, sender, eval) = circ.to_hidden();
+
+        let values_sender = map_values_to_keys(
+            sender,
+            vec![("b".to_string(), false), ("c".to_string(), true)],
+        );
+
+        let values_eval = map_values_to_keys(eval, vec![("a".to_string(), true)]);
+
+        let out = hidden_circ.evaluate(values_sender, values_eval);
+
+        assert!(out == true);
+    }
 }