set_commitment.tcc

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/** @file
 *****************************************************************************
 
 Implementation of a Merkle tree based set commitment scheme.
 
 *****************************************************************************
 * @author     This file is part of libsnark, developed by SCIPR Lab
 *             and contributors (see AUTHORS).
 * @copyright  MIT license (see LICENSE file)
 *****************************************************************************/
 
#ifndef SET_COMMITMENT_TCC_
#define SET_COMMITMENT_TCC_
 
namespace libsnark
{
 
template<typename HashT>
set_commitment_accumulator<HashT>::set_commitment_accumulator(
    const size_t max_entries, const size_t value_size)
    : value_size(value_size)
{
    depth = libff::log2(max_entries);
    digest_size = HashT::get_digest_len();
 
    tree.reset(new merkle_tree<HashT>(depth, digest_size));
}
 
template<typename HashT>
void set_commitment_accumulator<HashT>::add(const libff::bit_vector &value)
{
    assert(value_size == 0 || value.size() == value_size);
    const libff::bit_vector hash = HashT::get_hash(value);
    if (hash_to_pos.find(hash) == hash_to_pos.end()) {
        const size_t pos = hash_to_pos.size();
        tree->set_value(pos, hash);
        hash_to_pos[hash] = pos;
    }
}
 
template<typename HashT>
bool set_commitment_accumulator<HashT>::is_in_set(
    const libff::bit_vector &value) const
{
    assert(value_size == 0 || value.size() == value_size);
    const libff::bit_vector hash = HashT::get_hash(value);
    return (hash_to_pos.find(hash) != hash_to_pos.end());
}
 
template<typename HashT>
set_commitment set_commitment_accumulator<HashT>::get_commitment() const
{
    return tree->get_root();
}
 
template<typename HashT>
set_membership_proof set_commitment_accumulator<HashT>::get_membership_proof(
    const libff::bit_vector &value) const
{
    const libff::bit_vector hash = HashT::get_hash(value);
    auto it = hash_to_pos.find(hash);
    assert(it != hash_to_pos.end());
 
    set_membership_proof proof;
    proof.address = it->second;
    proof.merkle_path = tree->get_path(it->second);
 
    return proof;
}
 
} // namespace libsnark
 
#endif // SET_COMMITMENT_TCC_