darkfi/proofs/mimc.psm

{% include 'mimc_constants.psm' %}

contract mimc
    param left_0
    param right

    {# Jinja cannot set variables inside loops so use this hack #}
    {% set ns = namespace(right="right") %}

    {% for i in range(322) %}
        # Each round perform these steps:
        # xL, xR := xR + (xL + Ci)^3, xL

        local mimc_const
        load mimc_const mimc_constant_{{i}}

        private tmp_{{i}}
        set tmp_{{i}} left_{{i}}
        add tmp_{{i}} mimc_const
        square tmp_{{i}}

        lc0_add left_{{i}}
        lc0_add_constant mimc_constant_{{i}}
        lc1_add left_{{i}}
        lc1_add_constant mimc_constant_{{i}}
        lc2_add tmp_{{i}}
        enforce

        # new_xL = xR + (xL + Ci)^3
        # new_xL = xR + tmp * (xL + Ci)
        # new_xL - xR = tmp * (xL + Ci)
        private left_{{i+1}}
        set left_{{i+1}} left_{{i}}
        add left_{{i+1}} mimc_const
        mul left_{{i+1}} tmp_{{i}}
        add left_{{i+1}} {{ns.right}}

        lc0_add tmp_{{i}}
        lc1_add left_{{i}}
        lc1_add_constant mimc_constant_{{i}}
        lc2_add left_{{i+1}}
        lc2_sub {{ns.right}}
        enforce

        # xR = xL
        # right_{{i+1}} = left_{{i}}
        {% set ns.right = "left_" + i|string %}

        # xL = new_xL
    {% endfor %}

    public hash_result
    set hash_result left_322

    lc0_add left_322
    lc1_add_one
    lc2_add hash_result
    enforce
end