Pact ZK Hashes

This packages contains hash algorithms for use in ZK contracts in Pact, on the Kadena blockchain.

• MiMC (Sponge contstruction version)
• Poseidon

---

MiMC

Pact implementation of the MiMC hash for Kadena.

Compatible with Circom's and ZoKrates's Sponge construction with 220 Rounds:

https://iden3.io/circom

https://github.com/iden3/circomlib/blob/master/circuits/mimcsponge.circom

https://github.com/iden3/circomlibjs/blob/main/src/mimcsponge.js

https://github.com/Zokrates/ZoKrates/tree/develop/zokrates_stdlib/stdlib/hashes/mimcSponge

Constants are generated by keccak256 using the seed mimcsponge

API

(defun feistel-hash:object (key:integer input:object)

• key: key
• input: hashing object : {'L:integer 'R:integer}

Returns an hashing object: {'L:integer 'R:integer}

Gas consumption (pact <= 4.7.x):

• 27,697

Gas consumption (pact >= 4.8):

• 5,513

Equivalence:

Library	Function
Circomlib	MiMCFeistel(220)
CircomlibJS	MIMCSponge.hash()
ZoKrates Stdlib	mimcFeistel(field xL_in, field xR_in, field k) -> field[2]

---

(defun feistel-multi-hash:[integer] (key:integer inputs:[integer] n-outputs:integer)

• key: key
• inputs: input list of integers
• n-outputs: Number of outputs integer to return

Returns the hash result as a list of integers.

Gas consumption (pact <= 4.7.x):

• 1 input/1 output: 27,724
• 1 input/10 outputs: 277,160
• 10 inputs/1 output: 277,189
• 10 inputs/10 outputs: 526,638

Gas consumption (pact >= 4.8):

• 1 input/1 output: 5,540
• 1 input/10 outputs: 53,323
• 10 inputs/1 output: 55,175
• 10 inputs/10 outputs: 104,958

Equivalence:

Library	Function
Circomlib	MiMCSponge(nInputs, 220, nOutputs)
CircomlibJS	MIMCSponge.multiHash()
ZoKrates Stdlib	mimcSponge<nInputs, nOutputs>(field[nInputs] ins, field k) -> field[nOutputs]

---

---

POSEIDON

Pact implementation of the Poseidon hash for Kadena:

https://www.poseidon-hash.info/

https://github.com/iden3/circomlib/blob/master/circuits/poseidon.circom

https://github.com/iden3/circomlibjs/blob/main/src/poseidon_reference.js

https://github.com/Zokrates/ZoKrates/blob/develop/zokrates_stdlib/stdlib/hashes/poseidon/poseidon.zok

Constants are taken from the circomlib project.

API

(defun poseidon-hash:integer (in:[integer])

• inputs: input list of integers

Returns the hash result as an integer.

Gas consumption (pact <= 4.7.x):

• 1 input/1 output: 19,928
• 2 inputs/1 output: 35,091
• 3 inputs/1 output: 55,473
• 4 inputs/1 output: 87,146
• 5 inputs/1 output: 121,596

Gas consumption (pact >= 4.8):

• 1 input/1 output: 5,048
• 2 inputs/1 output: 7,828
• 3 inputs/1 output: 11,142
• 4 inputs/1 output: 16,273
• 5 inputs/1 output: 21,544

Equivalence:

Library	Function
Circomlib	Poseidon(nInputs)
CircomlibJS	buildPoseidon()(inputs, 0 1)
ZoKrates Stdlib	poseidon(field[N] inputs) -> field