prac/baltree.cpp

#include <functional>

#include "types.hpp"
#include "duoram.hpp"
#include "baltree.hpp"

struct Cell {
    RegAS key;
    RegXS pointers;
    RegXS value;

    // The width (the number of RegAS and RegXS entries) of this type
    static const size_t WIDTH = 3;

    void dump() const {
        printf("[%016lx %016lx %016lx]", key.share(), pointers.share(),
            value.share());
    }

    // You'll need to be able to create a random element, and do the
    // operations +=, +, -=, - (binary and unary).  Note that for
    // XOR-shared fields, + and - are both really XOR.

    inline void randomize() {
        key.randomize();
        pointers.randomize();
        value.randomize();
    }

    inline Cell &operator+=(const Cell &rhs) {
        this->key += rhs.key;
        this->pointers += rhs.pointers;
        this->value += rhs.value;
        return *this;
    }

    inline Cell operator+(const Cell &rhs) const {
        Cell res = *this;
        res += rhs;
        return res;
    }

    inline Cell &operator-=(const Cell &rhs) {
        this->key -= rhs.key;
        this->pointers -= rhs.pointers;
        this->value -= rhs.value;
        return *this;
    }

    inline Cell operator-(const Cell &rhs) const {
        Cell res = *this;
        res -= rhs;
        return res;
    }

    inline Cell operator-() const {
        Cell res;
        res.key = -this->key;
        res.pointers = -this->pointers;
        res.value = -this->value;
        return res;
    }

    // Multiply each field by the local share of the corresponding field
    // in the argument
    inline Cell mulshare(const Cell &rhs) const {
        Cell res = *this;
        res.key.mulshareeq(rhs.key);
        res.pointers.mulshareeq(rhs.pointers);
        res.value.mulshareeq(rhs.value);
        return res;
    }

    // You need a method to turn a leaf node of a DPF into a share of a
    // unit element of your type.  Typically set each RegAS to
    // dpf.unit_as(leaf) and each RegXS or RegBS to dpf.unit_bs(leaf).
    // Note that RegXS will extend a RegBS of 1 to the all-1s word, not
    // the word with value 1.  This is used for ORAM reads, where the
    // same DPF is used for all the fields.
    inline void unit(const RDPF &dpf, DPFnode leaf) {
        key = dpf.unit_as(leaf);
        pointers = dpf.unit_bs(leaf);
        value = dpf.unit_bs(leaf);
    }

    // You need a method to turn WIDTH DPFs into an element of your
    // type, using each DPF's scaled_sum or scaled_xor value as
    // appropriate for each field.  We need WIDTH of them because
    // reusing a scaled value from a DPF leaks information.  The dpfs
    // argument is a function that given 0 <= f < WIDTH, returns a
    // reference to DPF number f.
    inline void scaled_value(std::function<const RDPF &(size_t)> dpfs) {
        key = dpfs(0).scaled_sum;
        pointers = dpfs(1).scaled_xor;
        value = dpfs(2).scaled_xor;
    }
};

template <typename T>
T& operator>>(T& is, Cell &x)
{
    is >> x.key >> x.pointers >> x.value;
    return is;
}

template <typename T>
T& operator<<(T& os, const Cell &x)
{
    os << x.key << x.pointers << x.value;
    return os;
}

DEFAULT_TUPLE_IO(Cell)

void baltree (MPCIO &mpcio,
    const PRACOptions &opts, char **args)
{
    nbits_t depth=4;

    if (*args) {
        depth = atoi(*args);
        ++args;
    }

    MPCTIO tio(mpcio, 0, opts.num_threads);
    run_coroutines(tio, [&tio, depth] (yield_t &yield) {
        size_t size = size_t(1)<<depth;
        Duoram<Cell> oram(tio.player(), size);
        auto A = oram.flat(tio, yield);
        Cell c;
        c.key.set(0x0102030405060708);
        c.pointers.set(0x1112131415161718);
        c.value.set(0x2122232425262728);
        A[0] = c;
        RegAS idx;
        Cell expl_read_c = A[0];
        printf("expl_read_c = ");
        expl_read_c.dump();
        printf("\n");
        Cell oram_read_c = A[idx];
        printf ("oram_read_c = ");
        oram_read_c.dump();
        printf("\n");

        printf("\n");
        oram.dump();
    });
}