Fix

src/commitment/blake2s/mod.rs

@@ -1,7 +1,7 @@
 use super::CommitmentScheme;
 use crate::Error;
 use ark_std::rand::Rng;
-use blake2::Blake2s as b2s;
+use blake2::Blake2s256 as b2s;
 use digest::Digest;
 
 pub struct Commitment;

src/prf/blake2s/constraints.rs

@@ -396,7 +396,8 @@ mod test {
 
     use crate::prf::blake2s::{constraints::evaluate_blake2s, Blake2s as B2SPRF};
     use ark_relations::r1cs::ConstraintSystem;
-    use blake2::VarBlake2s;
+    use blake2::Blake2s256;
+    use digest::{Digest, FixedOutput};
 
     use super::Blake2sGadget;
     use ark_r1cs_std::prelude::*;
@@ -483,15 +484,13 @@ mod test {
         let mut rng = ark_std::test_rng();
 
         for input_len in (0..32).chain((32..256).filter(|a| a % 8 == 0)) {
-            use digest::*;
-            let mut h = VarBlake2s::new_keyed(&[], 32);
+            let mut h = Blake2s256::new();
 
             let data: Vec<u8> = (0..input_len).map(|_| rng.gen()).collect();
 
             h.update(&data);
 
-            let mut hash_result = Vec::with_capacity(digest::VariableOutput::output_size(&h));
-            h.finalize_variable(|res| hash_result.extend_from_slice(res));
+            let hash_result = h.finalize_fixed();
 
             let cs = ConstraintSystem::<Fr>::new_ref();
 

src/prf/blake2s/mod.rs

@@ -1,6 +1,5 @@
 use crate::Vec;
-use ark_std::convert::TryFrom;
-use blake2::{Blake2s as B2s, VarBlake2s};
+use blake2::{Blake2s256 as B2s, Blake2sMac};
 use digest::Digest;
 
 use super::PRF;
@@ -31,58 +30,21 @@ impl PRF for Blake2s {
 
 #[derive(Clone)]
 pub struct Blake2sWithParameterBlock {
-    pub digest_length: u8,
-    pub key_length: u8,
-    pub fan_out: u8,
-    pub depth: u8,
-    pub leaf_length: u32,
-    pub node_offset: u32,
-    pub xof_digest_length: u16,
-    pub node_depth: u8,
-    pub inner_length: u8,
+    pub output_size: u8,
+    pub key_size: u8,
     pub salt: [u8; 8],
     pub personalization: [u8; 8],
 }
 
 impl Blake2sWithParameterBlock {
-    pub fn parameters(&self) -> [u32; 8] {
-        let mut parameters = [0; 8];
-        parameters[0] = u32::from_le_bytes([
-            self.digest_length,
-            self.key_length,
-            self.fan_out,
-            self.depth,
-        ]);
-        parameters[1] = self.leaf_length;
-        parameters[2] = self.node_offset;
-        parameters[3] = u32::from_le_bytes([
-            self.xof_digest_length as u8,
-            (self.xof_digest_length >> 8) as u8,
-            self.node_depth,
-            self.inner_length,
-        ]);
-
-        let salt_bytes_1 = <[u8; 4]>::try_from(&self.salt[0..4]).unwrap();
-        let salt_bytes_2 = <[u8; 4]>::try_from(&self.salt[4..8]).unwrap();
-        let personalization_bytes_1 = <[u8; 4]>::try_from(&self.personalization[0..4]).unwrap();
-        let personalization_bytes_2 = <[u8; 4]>::try_from(&self.personalization[4..8]).unwrap();
-
-        parameters[4] = u32::from_le_bytes(salt_bytes_1);
-        parameters[5] = u32::from_le_bytes(salt_bytes_2);
-        parameters[6] = u32::from_le_bytes(personalization_bytes_1);
-        parameters[7] = u32::from_le_bytes(personalization_bytes_2);
-
-        parameters
-    }
-
     pub fn evaluate(&self, input: &[u8]) -> Vec<u8> {
-        use digest::*;
+        use digest::{typenum::U32, FixedOutput, Update};
         let eval_time = start_timer!(|| "Blake2sWithParameterBlock::Eval");
-        let mut h = VarBlake2s::with_parameter_block(&self.parameters());
+        let mut h =
+            Blake2sMac::<U32>::new_with_salt_and_personal(&[], &self.salt, &self.personalization)
+                .unwrap();
         h.update(input.as_ref());
         end_timer!(eval_time);
-        let mut buf = Vec::with_capacity(digest::VariableOutput::output_size(&h));
-        h.finalize_variable(|res| buf.extend_from_slice(res));
-        buf
+        h.finalize_fixed().into_iter().collect()
     }
 }

src/signature/mod.rs

@@ -56,7 +56,7 @@ mod test {
     use ark_ec::Group;
     use ark_ed_on_bls12_381::EdwardsProjective as JubJub;
     use ark_std::{test_rng, vec::Vec, UniformRand};
-    use blake2::Blake2s;
+    use blake2::Blake2s256 as Blake2s;
 
     fn sign_and_verify<S: SignatureScheme>(message: &[u8]) {
         let rng = &mut test_rng();