Add verify_transform utility.

Cargo.toml

@@ -14,6 +14,9 @@ required-features = ["verification"]
 [[bin]]
 name = "compute"
 
+[[bin]]
+name = "verify_transform"
+
 [dependencies]
 phase2 = "0.2.1"
 pairing = "0.14"

src/bin/verify.rs

@@ -13,13 +13,13 @@ fn main() {
     let params = File::open("params").unwrap();
     let mut params = BufReader::with_capacity(1024 * 1024, params);
 
-    let sapling_spend = phase2::MPCParameters::read(&mut params, false)
+    let sapling_spend = phase2::MPCParameters::read(&mut params, true)
         .expect("couldn't deserialize Sapling Spend params");
 
-    let sapling_output = phase2::MPCParameters::read(&mut params, false)
+    let sapling_output = phase2::MPCParameters::read(&mut params, true)
         .expect("couldn't deserialize Sapling Output params");
 
-    let sprout_joinsplit = phase2::MPCParameters::read(&mut params, false)
+    let sprout_joinsplit = phase2::MPCParameters::read(&mut params, true)
         .expect("couldn't deserialize Sprout JoinSplit params");
 
     let sapling_spend_contributions = sapling_spend.verify(sapling_crypto::circuit::sapling::Spend {

src/bin/verify_transform.rs

@@ -0,0 +1,66 @@
+extern crate phase2;
+extern crate pairing;
+extern crate blake2_rfc;
+
+use std::fs::File;
+use std::io::BufReader;
+use blake2_rfc::blake2b::Blake2b;
+
+fn main() {
+    let params = File::open("params").unwrap();
+    let mut params = BufReader::with_capacity(1024 * 1024, params);
+
+    let new_params = File::open("new_params").unwrap();
+    let mut new_params = BufReader::with_capacity(1024 * 1024, new_params);
+
+    let sapling_spend = phase2::MPCParameters::read(&mut params, false)
+        .expect("couldn't deserialize Sapling Spend params");
+
+    let sapling_output = phase2::MPCParameters::read(&mut params, false)
+        .expect("couldn't deserialize Sapling Output params");
+
+    let sprout_joinsplit = phase2::MPCParameters::read(&mut params, false)
+        .expect("couldn't deserialize Sprout JoinSplit params");
+
+    let new_sapling_spend = phase2::MPCParameters::read(&mut new_params, true)
+        .expect("couldn't deserialize Sapling Spend new_params");
+
+    let new_sapling_output = phase2::MPCParameters::read(&mut new_params, true)
+        .expect("couldn't deserialize Sapling Output new_params");
+
+    let new_sprout_joinsplit = phase2::MPCParameters::read(&mut new_params, true)
+        .expect("couldn't deserialize Sprout JoinSplit new_params");
+
+    let h1 = match phase2::verify_contribution(&sapling_spend, &new_sapling_spend) {
+        Ok(hash) => hash,
+        Err(_) => panic!("invalid transformation!")
+    };
+
+    let h2 = match phase2::verify_contribution(&sapling_output, &new_sapling_output) {
+        Ok(hash) => hash,
+        Err(_) => panic!("invalid transformation!")
+    };
+
+    let h3 = match phase2::verify_contribution(&sprout_joinsplit, &new_sprout_joinsplit) {
+        Ok(hash) => hash,
+        Err(_) => panic!("invalid transformation!")
+    };
+
+    let mut h = Blake2b::new(64);
+    h.update(&h1);
+    h.update(&h2);
+    h.update(&h3);
+    let h = h.finalize();
+
+    println!("{}", into_hex(h.as_ref()));
+}
+
+fn into_hex(h: &[u8]) -> String {
+    let mut f = String::new();
+
+    for byte in &h[..] {
+        f += &format!("{:02x}", byte);
+    }
+
+    f
+}