Sample class group discriminant faster

fastcrypto-vdf/Cargo.toml

@@ -25,6 +25,7 @@ experimental = []
 [dev-dependencies]
 hex = "0.4.3"
 criterion = "0.5.1"
+rand = "0.8.4"
 
 [[bench]]
 name = "vdf"

fastcrypto-vdf/benches/vdf.rs

@@ -5,12 +5,13 @@
 extern crate criterion;
 
 use criterion::measurement::Measurement;
-use criterion::{BenchmarkGroup, Criterion};
+use criterion::{BenchmarkGroup, BenchmarkId, Criterion};
 use fastcrypto_vdf::class_group::{Discriminant, QuadraticForm};
 use fastcrypto_vdf::vdf::wesolowski::ClassGroupVDF;
 use fastcrypto_vdf::vdf::VDF;
 use num_bigint::BigInt;
 use num_traits::Num;
+use rand::{thread_rng, RngCore};
 
 struct VerificationInputs {
     iterations: u64,
@@ -48,29 +49,57 @@ fn verify(c: &mut Criterion) {
 
     let mut group = c.benchmark_group(format!("VDF verify ({})", dep));
 
-    // Note that the number of iterations are quite low, but this has very little influence on the benchmark results.
-
     //1024 bits
     verify_single(VerificationInputs {
-            iterations: 1000,
+            iterations: 4000000,
             discriminant: "cd711f181153e08e08e5ba156db0c4e9469de76f2bd6b64f068f5007918727f5eaa5f6a0e090f82682a4ebf87befdea8f1253265d700ee3ca6b0fdb2677c633c7f37b62f0e0c13b402def0ba9abaf15e4c53bfb6bda0c7a0cad4439864af3eb9af6d6c4b10286eb8ff5e2de5b009196bc60c3000fde8d4b89b7674e61bc2d23f".to_string(),
-            result: "030039c78c39cff6c29052bfc1453616ec7a47251509b9dbc33d1036bebd4d12e6711a51deb327120310f96be04c90fd4c3b1dab9617c3133132b827abe7bb2348707da8164b964e1b95cd6a8eaf36ffb80bab1f750410e793daec8228b222bd00370100".to_string(),
-            proof: "000075d043db5f619f5cb4e8ef7729c7cac154434c33d6e52dd086b90a52c7b1231890eda9d1365100e88993e332f0a99bb7763f215de2fb6b632445beeeff22b657dc90d4e110ed03eac10ec445117d211208c79dd4933ba58b8e17b4c54ef1824c0100".to_string(),
+            result: "02007e64ab640cfd39daeaeab7400797917a2635fca5988ae1ba5e9a7a0b234faf361ae103d36d0838574524a5bc0a6b0bdd8f5e8c90774e92194df23fd5929b343bc7e47a1a07270949ae1b37505a63414aec987e06eabc6738d1ec02b32d6da3690100".to_string(),
+            proof: "0200c879069103e13f66c38ac8f34a8ec48ec7033f442128de49c7adf0732359e4da4682bff7ad6a2ca2767a39f9eaf4dec9c80fb950d2cb603458738b3d0e17855e6bf0586455e99e75fa23f0ae59e1a922c1d5b18b234428766028f5856b872f720100".to_string(),
         }, &mut group);
 
     // 2048 bits
     verify_single(VerificationInputs {
-            iterations: 1000,
+            iterations: 4000000,
             discriminant: "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".to_string(),
-            result: "02001222c470df6df6e1321aa1c28279d0c64663c7f066888ff6cd854dcd5deb71f63dfe0b867675180fada390e0d7b1ff735b55fea2b88123a32d1e1239126b275578ea26a4a89e5ef290e2b7b8d072ab819d5b9422770339dc87fd4dc4ebf6add3e391067a557be4be5436355ab11035609d5a3dc71e95cf2a0dcbb228b85d9750a1dc670ac51822d7eff49b5cacd4a8cc485e53bbf7e44f95e7fd5ec55fca44eb91c4831b1e839d8b4c8453dce8be69698bc5cb8fa45120d201057e4d72a6746b0100".to_string(),
-            proof: "03008b91b20ab570b701d394aa095d8c670d95a8a3b26af966e979a27acf417421360ea54014668a121139ab11fe92cc0a8d192a8a675f244f3016ed23a7a82d9dd70de089d5bcb5bb0c9535923b2656b19c8cf0cc6e0e4c800c44fc17e16a1b96572f6e0e0967709af259b854a51bec270e5cf73cc4efa93791ac6a84dc2ab77f02d0234ac60b2a04740644ac845204c67f9063ab139e9a0eb25c4417c892ca52299202d3854243d7eb58cc46a837745a1eb92699eb89138eec89467f7226380b040600".to_string(),
+            result: "0000d37421051f4f437a727a8d21825ef02a9c33744766947a59140d532756f231d42d8add13fe76e747b130a29becb75c3a3389ee1472325a479afb4275b7e9cf0cedc957e4409cfdea69e901fc8d810617381c0492de46e0387ee42eb3065468ceec55d17f072fa691341ff5b6d835abf35a47b90c127658c4bf4ec8ea6a4ae4177bd96aad7454c36e7bde4bb360a519c9d7b73ecd776d44d18d6441bc5fbe8724227c623477b5c307b89dcea707e1db547d4d0e8c7814e9f24ceedb55653585310100".to_string(),
+            proof: "02000607e9272f517e3d7aaa2d3f5bcb5925b9e9c46e432b6b292223df502cc4487b5841d9c4f3746adfd1f058482220d38ddf4c6daf30d9cc0cf0cebb36a5b1ef9189e4ed78b022fae17b9fc2e16c6d3450df52877f67b3c7c06db17eb1f1ecb8c78310aa622935ff76abfb3bdf153604359438c1364269a80dd434149b658a6b6629ec86ba04a339b07b4ab71c1f2417c64a2cfa49138a62d0c02e753c1060df68a3f9ed04fc357742b6f927f7550ba79e52c429031ba3f353b9dd5fef6147c4190100".to_string(),
         }, &mut group);
 }
 
+fn sample_discriminant(c: &mut Criterion) {
+    #[cfg(not(feature = "gmp"))]
+    let dep = "num-bigint";
+
+    #[cfg(feature = "gmp")]
+    let dep = "gmp";
+
+    let bit_lengths = [128, 256, 512, 1024, 2048];
+
+    let mut seed = [0u8; 32];
+
+    let mut rng = thread_rng();
+
+    for bit_length in bit_lengths {
+        c.bench_with_input(
+            BenchmarkId::new(
+                format!("Sample class group discriminant ({})", dep),
+                bit_length,
+            ),
+            &bit_length,
+            |b, n| {
+                b.iter(|| {
+                    rng.try_fill_bytes(&mut seed).unwrap();
+                    Discriminant::from_seed(&seed, *n).unwrap();
+                })
+            },
+        );
+    }
+}
+
 criterion_group! {
     name = vdf_benchmarks;
     config = Criterion::default().sample_size(100);
-    targets = verify,
+    targets = verify, sample_discriminant
 }
 
 criterion_main!(vdf_benchmarks);

fastcrypto-vdf/src/vdf/wesolowski.rs

@@ -8,9 +8,8 @@ use fastcrypto::error::FastCryptoError::{InvalidInput, InvalidProof};
 use fastcrypto::error::FastCryptoResult;
 use fastcrypto::hash::HashFunction;
 use fastcrypto::hash::Sha256;
-use num_bigint::{BigInt, Sign};
+use num_bigint::{BigInt, BigUint, Sign};
 use num_integer::Integer;
-use num_prime::nt_funcs::is_prime;
 use std::cmp::min;
 use std::marker::PhantomData;
 use std::ops::Neg;
@@ -204,12 +203,23 @@ fn hash_prime(seed: &[u8], length: usize, bitmask: &[usize]) -> FastCryptoResult
         // The implementations of the primality test used below might be slightly different from the
         // one used by chiavdf, but since the risk of a false positive is very small (4^{-100}) this
         // is not an issue.
-        if is_prime(&x.to_biguint().unwrap(), None).probably() {
+        if is_prime(&x.to_biguint().unwrap()) {
             return Ok(x);
         }
     }
 }
 
+#[cfg(feature = "gmp")]
+fn is_prime(x: &BigUint) -> bool {
+    let y = rug::Integer::from_digits(&x.to_bytes_be(), rug::integer::Order::Msf);
+    y.is_probably_prime(30) != rug::integer::IsPrime::No
+}
+
+#[cfg(not(feature = "gmp"))]
+fn is_prime(x: &BigUint) -> bool {
+    num_prime::nt_funcs::is_prime(x, None).probably()
+}
+
 impl Discriminant {
     /// Compute a valid discriminant (aka a negative prime equal to 3 mod 4) based on the given seed.
     pub fn from_seed(seed: &[u8], length: usize) -> FastCryptoResult<Self> {