Pedersen hash

The Pedersen hash of two elements x and y can be found using the hash2(x, y) module from the Cairo common library.

%lang starknet
%builtins pedersen

from starkware.cairo.common.cairo_builtins import HashBuiltin
from starkware.cairo.common.hash import hash2

@view
func get_hash{pedersen_ptr: HashBuiltin*}(x, y) -> (
        hash: felt , hash_with_zero: felt):
    # Pedersen hash of x and y.
    # The hash function used will be the pointer that is passed.
    let (hash) = hash2{hash_ptr=pedersen_ptr}(x, y)

    # Hash of x and 0. Equivalent to the hash of x alone.
    let (hash_with_zero) = hash2{hash_ptr=pedersen_ptr}(x, 0)

    return (hash, hash_with_zero)
end

Save as pedersen_hash.cairo.

Compile

Then, to compile:

starknet-compile pedersen_hash.cairo \
    --output pedersen_hash_compiled.json \
    --abi pedersen_hash_contract_abi.json

Deploy

Then, to deploy:

starknet deploy --contract pedersen_hash_compiled.json \
    --network=alpha

Returns:
Deploy transaction was sent.
Contract address: 0x02fe395f2c3467b6458017e5ff69fd992f46b75b8efb919f97b6724906bfa235
Transaction ID: 182130

Note: Remove the zero after the x, 0x[0]12345. E.g., 0x0123abc becomes 0x123abc.

Monitor

Check the status of the transaction:

starknet tx_status --network=alpha --id=182130

Returns:
{
    "block_id": 41371,
    "tx_status": "PENDING"
}

The block and the contract

Interact

Then, to interact:

starknet call \
    --network=alpha \
    --address 0x2fe395f2c3467b6458017e5ff69fd992f46b75b8efb919f97b6724906bfa235 \
    --abi pedersen_hash_contract_abi.json \
    --function get_hash \
    --inputs 13579 123

Returns:
1991472738936771294314932046141177383402302165974022666190392465136523753950

2255487090060981340412778270523682108366421523848318719210969003889439916982

This is the hash of (13579, 123) and (13579, 0) respectively.

Status options:

• NOT_RECEIVED: The transaction has not been received yet (i.e., not written to storage).
• RECEIVED: The transaction was received by the operator.
  • PENDING: The transaction passed the validation and is waiting to be sent on-chain.
    • REJECTED: The transaction failed validation and thus was skipped.
    • ACCEPTED_ONCHAIN: The transaction was accepted on-chain.

Visit the voyager explorer to see the transactions.