cl: drop blake2; print prover time

cl/src/crypto.rs

@@ -1,6 +1,6 @@
-use blake2::Blake2b512;
+use sha2::Sha512;
 use curve25519_dalek::ristretto::RistrettoPoint;
 
 pub fn hash_to_curve(bytes: &[u8]) -> RistrettoPoint {
-    RistrettoPoint::hash_from_bytes::<Blake2b512>(bytes)
+    RistrettoPoint::hash_from_bytes::<Sha512>(bytes)
 }

cl/src/note.rs

@@ -1,4 +1,4 @@
-use blake2::{Blake2s256, Digest};
+use sha2::{Digest, Sha256};
 use rand_core::CryptoRngCore;
 use serde::{Deserialize, Serialize};
 
@@ -40,7 +40,7 @@ impl NoteWitness {
     }
 
     pub fn commit(&self, nf_pk: NullifierCommitment, nonce: NullifierNonce) -> NoteCommitment {
-        let mut hasher = Blake2s256::new();
+        let mut hasher = Sha256::new();
         hasher.update(b"NOMOS_CL_NOTE_COMMIT");
 
         // COMMIT TO BALANCE

goas/host/src/main.rs

@@ -78,11 +78,16 @@ fn main() {
     // Obtain the default prover.
     let prover = default_prover();
 
+    
+    use std::time::Instant;
+    let start_t = Instant::now();
+
     // Proof information by proving the specified ELF binary.
     // This struct contains the receipt along with statistics about execution of the guest
     let opts = risc0_zkvm::ProverOpts::succinct();
     let prove_info = prover.prove_with_opts(env, METHOD_ELF, &opts).unwrap();
 
+    println!("STARK prover time: {:.2?}", start_t.elapsed());
     // extract the receipt.
     let receipt = prove_info.receipt;