1  // Copyright (c) 2019-2025 Alpha-Delta Network Inc.
  2  // This file is part of the alphavm library.
  3  
  4  // Licensed under the Apache License, Version 2.0 (the "License");
  5  // you may not use this file except in compliance with the License.
  6  // You may obtain a copy of the License at:
  7  
  8  // http://www.apache.org/licenses/LICENSE-2.0
  9  
 10  // Unless required by applicable law or agreed to in writing, software
 11  // distributed under the License is distributed on an "AS IS" BASIS,
 12  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 13  // See the License for the specific language governing permissions and
 14  // limitations under the License.
 15  
 16  use super::*;
 17  
 18  impl<E: Environment, const RATE: usize> PRF for Poseidon<E, RATE> {
 19      type Input = Field<E>;
 20      type Output = Field<E>;
 21      type Seed = Field<E>;
 22  
 23      #[inline]
 24      fn prf(&self, seed: &Self::Seed, input: &[Self::Input]) -> Self::Output {
 25          // Construct the preimage: seed || input.
 26          let mut preimage = Vec::with_capacity(1 + input.len());
 27          preimage.push(seed.clone());
 28          preimage.extend_from_slice(input);
 29  
 30          // Hash the preimage to derive the PRF output.
 31          self.hash(&preimage)
 32      }
 33  }
 34  
 35  #[cfg(test)]
 36  mod tests {
 37      use super::*;
 38      use alphavm_circuit_types::environment::Circuit;
 39      use alphavm_utilities::{TestRng, Uniform};
 40  
 41      use anyhow::Result;
 42  
 43      const DOMAIN: &str = "PoseidonCircuit0";
 44      const ITERATIONS: usize = 10;
 45      const RATE: usize = 4;
 46  
 47      fn check_prf(
 48          mode: Mode,
 49          num_inputs: usize,
 50          num_constants: u64,
 51          num_public: u64,
 52          num_private: u64,
 53          num_constraints: u64,
 54          rng: &mut TestRng,
 55      ) -> Result<()> {
 56          use console::PRF as P;
 57  
 58          let native = console::Poseidon::<<Circuit as Environment>::Network, RATE>::setup(DOMAIN)?;
 59          let poseidon = Poseidon::<Circuit, RATE>::constant(native.clone());
 60  
 61          for i in 0..ITERATIONS {
 62              // Prepare the seed.
 63              let native_seed = Uniform::rand(rng);
 64              let seed = Field::new(mode, native_seed);
 65  
 66              // Prepare the preimage.
 67              let native_input = (0..num_inputs).map(|_| Uniform::rand(rng)).collect::<Vec<_>>();
 68              let input = native_input.iter().map(|v| Field::<Circuit>::new(mode, *v)).collect::<Vec<_>>();
 69  
 70              // Compute the native hash.
 71              let expected = native.prf(&native_seed, &native_input).expect("Failed to PRF native input");
 72  
 73              // Compute the circuit hash.
 74              Circuit::scope(format!("Poseidon PRF {mode} {i}"), || {
 75                  let candidate = poseidon.prf(&seed, &input);
 76                  assert_eq!(expected, candidate.eject_value());
 77                  let case = format!("(mode = {mode}, num_inputs = {num_inputs})");
 78                  assert_scope!(case, num_constants, num_public, num_private, num_constraints);
 79              });
 80              Circuit::reset();
 81          }
 82          Ok(())
 83      }
 84  
 85      #[test]
 86      fn test_prf_constant() -> Result<()> {
 87          let mut rng = TestRng::default();
 88  
 89          for num_inputs in 0..=RATE {
 90              check_prf(Mode::Constant, num_inputs, 1, 0, 0, 0, &mut rng)?;
 91          }
 92          Ok(())
 93      }
 94  
 95      #[test]
 96      fn test_prf_public() -> Result<()> {
 97          let mut rng = TestRng::default();
 98  
 99          check_prf(Mode::Public, 0, 1, 0, 335, 335, &mut rng)?;
100          check_prf(Mode::Public, 1, 1, 0, 340, 340, &mut rng)?;
101          check_prf(Mode::Public, 2, 1, 0, 345, 345, &mut rng)?;
102          check_prf(Mode::Public, 3, 1, 0, 350, 350, &mut rng)?;
103          check_prf(Mode::Public, 4, 1, 0, 705, 705, &mut rng)?;
104          check_prf(Mode::Public, 5, 1, 0, 705, 705, &mut rng)?;
105          check_prf(Mode::Public, 6, 1, 0, 705, 705, &mut rng)?;
106          check_prf(Mode::Public, 7, 1, 0, 705, 705, &mut rng)?;
107          check_prf(Mode::Public, 8, 1, 0, 1060, 1060, &mut rng)?;
108          check_prf(Mode::Public, 9, 1, 0, 1060, 1060, &mut rng)?;
109          check_prf(Mode::Public, 10, 1, 0, 1060, 1060, &mut rng)
110      }
111  
112      #[test]
113      fn test_prf_private() -> Result<()> {
114          let mut rng = TestRng::default();
115  
116          check_prf(Mode::Private, 0, 1, 0, 335, 335, &mut rng)?;
117          check_prf(Mode::Private, 1, 1, 0, 340, 340, &mut rng)?;
118          check_prf(Mode::Private, 2, 1, 0, 345, 345, &mut rng)?;
119          check_prf(Mode::Private, 3, 1, 0, 350, 350, &mut rng)?;
120          check_prf(Mode::Private, 4, 1, 0, 705, 705, &mut rng)?;
121          check_prf(Mode::Private, 5, 1, 0, 705, 705, &mut rng)?;
122          check_prf(Mode::Private, 6, 1, 0, 705, 705, &mut rng)?;
123          check_prf(Mode::Private, 7, 1, 0, 705, 705, &mut rng)?;
124          check_prf(Mode::Private, 8, 1, 0, 1060, 1060, &mut rng)?;
125          check_prf(Mode::Private, 9, 1, 0, 1060, 1060, &mut rng)?;
126          check_prf(Mode::Private, 10, 1, 0, 1060, 1060, &mut rng)
127      }
128  }