Poseidon hashing #11
Poseidon hashing #11
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| #[derive(Debug, Clone, Copy, Default, PartialEq, Eq, CanonicalDeserialize, CanonicalSerialize)] | ||
| pub struct PoseidonDigest(pub Fp); | ||
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| impl HashMarker for PoseidonDigest {} |
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I think this can be removed
| input1: U256::from(0), | ||
| input2: U256::from(0), | ||
| }; | ||
| let result = InstanceTrace::new(instance); |
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Using InstanceTrace will decrease performance since it is not optimised for speed but rather obtaining the values needed in the STARK trace.
I think this PR should implement a seperate poseidon hash function that's focussed more on performance (i.e. doesn't keep track of the state of rounds in the permutation). Let's move all the added methods and tests in this file to crypto/src/hash/poseidon.rs. I'd suggest using the parameters from builtins/src/poseidon/params.rs and using InstanceTrace::new as a guide. Let's put the implementation in a new function called poseidon_permutation([Fp; 3]).
| index: 0, | ||
| input0: U256::from_limbs(x.0 .0), | ||
| input1: U256::from(0), | ||
| input2: U256::from(0), |
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Might need to set input2 to 1
| index: 0, | ||
| input0: U256::from_limbs(x.0 .0), | ||
| input1: U256::from_limbs(y.0 .0), | ||
| input2: U256::from(0), |
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| } | ||
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| fn merge(v0: &PoseidonDigest, v1: &PoseidonDigest) -> PoseidonDigest { | ||
| PoseidonDigest(poseidon_hash_many([**v0, **v1].to_vec())) |
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Due to how frequently this function is called it has a big impact on the overall performance of the prover. Allocations on the heap every invocation makes this function much more expensive than it needs to be. Let's implement this without any Vec
| fn poseidon_hash_many_4_example() { | ||
| let elements = vec![Fp!("0"), Fp!("0"), Fp!("0"), Fp!("0")]; | ||
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| let expected = BigInt::new([ |
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How are all the expected values obtained?
| @@ -259,4 +324,70 @@ mod tests { | |||
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| assert_eq!(expected, permute([Fp::ZERO, Fp::ZERO, Fp::ZERO])); | |||
| } | |||
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| #[test] | |||
| fn poseidon_hash_many_3_example() { | |||
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test name can just be "hash_3_values". Let's update the other test names as well. Also we should have tests for hash_single and poseidon_hash
| fn merge_with_int(seed: &PoseidonDigest, value: u64) -> PoseidonDigest { | ||
| PoseidonDigest(poseidon_hash_many([**seed, value.into()].to_vec())) | ||
| } |
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| fn merge_with_int(seed: &PoseidonDigest, value: u64) -> PoseidonDigest { | |
| PoseidonDigest(poseidon_hash_many([**seed, value.into()].to_vec())) | |
| } | |
| fn merge_with_int(seed: &PoseidonDigest, value: u64) -> PoseidonDigest { | |
| self.merge(seed.0, value.into()) | |
| } |
| fn hash_elements(elements: impl IntoIterator<Item = Fp>) -> PoseidonDigest { | ||
| PoseidonDigest(poseidon_hash_many(elements.into_iter().collect())) | ||
| } |
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Let's make this function behave the same way as poseidon_hash_many_given_poseidon_perm and use the same padding rule
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