delegation.cpp

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// Copyright (c) 2020 The Bitcoin developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
#include <avalanche/delegation.h>
 
#include <avalanche/proof.h>
#include <avalanche/validation.h>
#include <hash.h>
#include <streams.h>
#include <util/strencodings.h>
#include <util/translation.h>
 
namespace avalanche {
 
bool Delegation::FromHex(Delegation &dg, const std::string &dgHex,
                         bilingual_str &errorOut) {
    if (!IsHex(dgHex)) {
        errorOut = _("Delegation must be an hexadecimal string.");
        return false;
    }
 
    CDataStream ss(ParseHex(dgHex), SER_NETWORK, PROTOCOL_VERSION);
 
    try {
        ss >> dg;
    } catch (std::exception &e) {
        errorOut = strprintf(_("Delegation has invalid format: %s"), e.what());
        return false;
    }
 
    return true;
}
 
template <typename L, typename F>
static bool reduceLevels(uint256 &hash, const std::vector<L> &levels, F f) {
    for (const auto &l : levels) {
        HashWriter ss{};
        ss << hash;
        ss << l.pubkey;
        hash = ss.GetHash();
 
        if (!f(l)) {
            return false;
        }
    }
 
    return true;
}
 
template <typename L>
static bool reduceLevels(uint256 &hash, const std::vector<L> &levels) {
    return reduceLevels(hash, levels, [](const L &) { return true; });
}
 
ProofId Delegation::getProofId() const {
    return limitedProofid.computeProofId(proofMaster);
}
 
const CPubKey &Delegation::getDelegatedPubkey() const {
    if (!levels.empty()) {
        return levels.back().pubkey;
    }
    return proofMaster;
}
 
DelegationId Delegation::computeDelegationId() const {
    uint256 hash = getProofId();
    reduceLevels(hash, levels);
    return DelegationId(hash);
}
 
bool Delegation::verify(DelegationState &state, CPubKey &auth) const {
    uint256 hash = getProofId();
    const CPubKey *pauth = &proofMaster;
 
    if (levels.size() > MAX_DELEGATION_LEVELS) {
        return state.Invalid(DelegationResult::TOO_MANY_LEVELS,
                             "too-many-levels");
    }
 
    bool ret = reduceLevels(hash, levels, [&](const Level &l) {
        if (!pauth->VerifySchnorr(hash, l.sig)) {
            return state.Invalid(DelegationResult::INVALID_SIGNATURE,
                                 "invalid-signature");
        }
 
        // This key is valid, now up to the next delegation level.
        pauth = &l.pubkey;
        return true;
    });
 
    auth = *pauth;
    return ret;
}
 
} // namespace avalanche