chore: delete poseidon2 from bn254_blackbox_solver (#8741)

This is no longer needed post #8740

noir/noir-repo/acvm-repo/bn254_blackbox_solver/src/lib.rs

@@ -13,10 +13,7 @@ mod schnorr;
 use ark_ec::AffineRepr;
 pub use embedded_curve_ops::{embedded_curve_add, multi_scalar_mul};
 pub use generator::generators::derive_generators;
-pub use poseidon2::{
-    field_from_hex, poseidon2_permutation, poseidon_hash, Poseidon2Config, Poseidon2Sponge,
-    POSEIDON2_CONFIG,
-};
+pub use poseidon2::{field_from_hex, poseidon2_permutation, Poseidon2Config, POSEIDON2_CONFIG};
 
 // Temporary hack, this ensure that we always use a bn254 field here
 // without polluting the feature flags of the `acir_field` crate.

noir/noir-repo/acvm-repo/bn254_blackbox_solver/src/poseidon2.rs

@@ -543,75 +543,6 @@ impl<'a> Poseidon2<'a> {
     }
 }
 
-/// Performs a poseidon hash with a sponge construction equivalent to the one in poseidon2.nr
-pub fn poseidon_hash(inputs: &[FieldElement]) -> Result<FieldElement, BlackBoxResolutionError> {
-    let two_pow_64 = 18446744073709551616_u128.into();
-    let iv = FieldElement::from(inputs.len()) * two_pow_64;
-    let mut sponge = Poseidon2Sponge::new(iv, 3);
-    for input in inputs.iter() {
-        sponge.absorb(*input)?;
-    }
-    sponge.squeeze()
-}
-
-pub struct Poseidon2Sponge<'a> {
-    rate: usize,
-    poseidon: Poseidon2<'a>,
-    squeezed: bool,
-    cache: Vec<FieldElement>,
-    state: Vec<FieldElement>,
-}
-
-impl<'a> Poseidon2Sponge<'a> {
-    pub fn new(iv: FieldElement, rate: usize) -> Poseidon2Sponge<'a> {
-        let mut result = Poseidon2Sponge {
-            cache: Vec::with_capacity(rate),
-            state: vec![FieldElement::zero(); rate + 1],
-            squeezed: false,
-            rate,
-            poseidon: Poseidon2::new(),
-        };
-        result.state[rate] = iv;
-        result
-    }
-
-    fn perform_duplex(&mut self) -> Result<(), BlackBoxResolutionError> {
-        // zero-pad the cache
-        for _ in self.cache.len()..self.rate {
-            self.cache.push(FieldElement::zero());
-        }
-        // add the cache into sponge state
-        for i in 0..self.rate {
-            self.state[i] += self.cache[i];
-        }
-        self.state = self.poseidon.permutation(&self.state, 4)?;
-        Ok(())
-    }
-
-    pub fn absorb(&mut self, input: FieldElement) -> Result<(), BlackBoxResolutionError> {
-        assert!(!self.squeezed);
-        if self.cache.len() == self.rate {
-            // If we're absorbing, and the cache is full, apply the sponge permutation to compress the cache
-            self.perform_duplex()?;
-            self.cache = vec![input];
-        } else {
-            // If we're absorbing, and the cache is not full, add the input into the cache
-            self.cache.push(input);
-        }
-        Ok(())
-    }
-
-    pub fn squeeze(&mut self) -> Result<FieldElement, BlackBoxResolutionError> {
-        assert!(!self.squeezed);
-        // If we're in absorb mode, apply sponge permutation to compress the cache.
-        self.perform_duplex()?;
-        self.squeezed = true;
-
-        // Pop one item off the top of the permutation and return it.
-        Ok(self.state[0])
-    }
-}
-
 #[cfg(test)]
 mod test {
     use acir::AcirField;
@@ -631,19 +562,4 @@ mod test {
         ];
         assert_eq!(result, expected_result);
     }
-
-    #[test]
-    fn hash_smoke_test() {
-        let fields = [
-            FieldElement::from(1u128),
-            FieldElement::from(2u128),
-            FieldElement::from(3u128),
-            FieldElement::from(4u128),
-        ];
-        let result = super::poseidon_hash(&fields).expect("should hash successfully");
-        assert_eq!(
-            result,
-            field_from_hex("130bf204a32cac1f0ace56c78b731aa3809f06df2731ebcf6b3464a15788b1b9"),
-        );
-    }
 }