darkfi/proofs/mint.pism

# :set syntax=pism
# :source ../scripts/pism.vim
constant G_VCV FixedGenerator
constant G_VCR FixedGenerator
constant CRH_IVK BlakePersonalization
#constant JUBJUB_FR_CAPACITY BinarySize
#constant NOTE_COMMIT PedersenPersonalization

contract mint_contract
    # Value commitment
    param value U64
    param asset_id U64
    param randomness_value Fr
    param randomness_asset Fr

    param serial Fr
    param randomness_coin Fr
    param public Point
start
    # Witness input values
    u64_as_binary_le value param:value
    u64_as_binary_le asset_id param:asset_id
    fr_as_binary_le randomness_value param:randomness_value
    fr_as_binary_le randomness_asset param:randomness_asset
    fr_as_binary_le serial param:serial
    fr_as_binary_le randomness_coin param:randomness_coin

    witness public param:public
    assert_not_small_order public

    # Make value commitment
    # V = v * G_VCV + r * G_VCR

    ec_mul_const vcv value G_VCV
    ec_mul_const rcv randomness_value G_VCR
    ec_add cv vcv rcv
    # emit cv
    emit_ec cv

    # Make asset_id commitment
    # A = a * G_VCV + r_a * G_VCR

    ec_mul_const vca asset_id G_VCV
    ec_mul_const rca randomness_asset G_VCR
    ec_add ca vca rca
    # emit ca
    emit_ec ca


    # Make the coin
    # C = Hash(public_key, value, asset_id, serial, randomness_coin)

    # Build the preimage to hash
    alloc_binary preimage

    # public_key
    ec_repr repr_public public
    binary_extend preimage repr_public

    # value
    binary_extend preimage value

    # asset_id
    binary_extend preimage asset_id

# Fr values are 252 bits so we need to pad it with extra 0s
# to match the Rust values which are 256 bits
{% macro binary_put_fr(binary, var) -%}
    binary_extend {{ binary }} {{ var }}
    {% for n in range(4) %}
        alloc_const_bit zero_bit false
        binary_push {{ binary }} zero_bit
    {% endfor %}
{%- endmacro %}

    # serial
    {{ binary_put_fr("preimage", "serial") }}

    # randomness_coin
    {{ binary_put_fr("preimage", "randomness_coin") }}

    # Public key:       SubgroupPoint   = 256 bits
    # Value:            u64             = 64 bits
    # Serial:           Fr              = 252 + 4 bits padding
    # Randomness coin   Fr              = 252 + 4 bits padding
    # TOTAL: 896 bits for preimage
    static_assert_binary_size preimage 896
    blake2s coin preimage CRH_IVK
    emit_binary coin
end