move header files to include/hotstuff

7 files changed, 2302 insertions, 0 deletions

diff --git a/include/hotstuff/client.h b/include/hotstuff/client.h
new file mode 100644
index 0000000..dd1cfee
--- /dev/null
+++ b/include/hotstuff/client.h
@@ -0,0 +1,66 @@
+#ifndef _HOTSTUFF_CLIENT_H
+#define _HOTSTUFF_CLIENT_H
+
+#include "type.h"
+#include "salticidae/msg.h"
+#include "entity.h"
+
+namespace hotstuff {
+
+enum {
+    REQ_CMD = 0x4,
+    RESP_CMD = 0x5,
+    CHK_CMD = 0x6
+};
+
+class CommandDummy: public Command {
+    static uint64_t cnt;
+    uint64_t n;
+    uint256_t hash;
+
+    public:
+
+    CommandDummy() {}
+
+    ~CommandDummy() override {}
+
+    CommandDummy(uint64_t n):
+        n(n), hash(salticidae::get_hash(*this)) {}
+
+    static command_t make_cmd() {
+        return new CommandDummy(cnt++);
+    }
+
+    void serialize(DataStream &s) const override {
+        s << n;
+    }
+
+    void unserialize(DataStream &s) override {
+        s >> n;
+        hash = salticidae::get_hash(*this);
+    }
+
+    const uint256_t &get_hash() const override {
+        return hash;
+    }
+
+    bool verify() const override {
+        return true;
+    }
+};
+
+struct MsgClient: public salticidae::MsgBase<> {
+    using MsgBase::MsgBase;
+    void gen_reqcmd(const Command &cmd);
+    void parse_reqcmd(CommandDummy &cmd) const;
+
+    void gen_respcmd(const uint256_t &cmd_hash, const Finality &fin);
+    void parse_respcmd(uint256_t &cmd_hash, Finality &fin) const;
+
+    void gen_chkcmd(const uint256_t &cmd_hash);
+    void parse_chkcmd(uint256_t &cmd_hash) const;
+};
+
+}
+
+#endif
diff --git a/include/hotstuff/core.h b/include/hotstuff/core.h
new file mode 100644
index 0000000..c7e1fe6
--- /dev/null
+++ b/include/hotstuff/core.h
@@ -0,0 +1,631 @@
+#ifndef _HOTSTUFF_CORE_H
+#define _HOTSTUFF_CORE_H
+
+#include <queue>
+#include <set>
+#include <unordered_map>
+#include <unordered_set>
+
+#include "salticidae/stream.h"
+#include "salticidae/util.h"
+#include "salticidae/network.h"
+#include "salticidae/msg.h"
+
+#include "promise.hpp"
+#include "util.h"
+#include "entity.h"
+#include "crypto.h"
+
+using salticidae::EventContext;
+using salticidae::Event;
+using salticidae::NetAddr;
+using salticidae::MsgNetwork;
+using salticidae::PeerNetwork;
+using salticidae::ElapsedTime;
+using salticidae::_1;
+using salticidae::_2;
+
+namespace hotstuff {
+
+const double ent_waiting_timeout = 10;
+const double double_inf = 1e10;
+
+enum {
+    PROPOSE = 0x0,
+    VOTE = 0x1,
+    QUERY_FETCH_BLK = 0x2,
+    RESP_FETCH_BLK = 0x3,
+};
+
+using promise::promise_t;
+
+struct Proposal;
+struct Vote;
+
+/** Abstraction for HotStuff protocol state machine (without network implementation). */
+class HotStuffCore {
+    block_t b0;                                  /** the genesis block */
+    /* === state variables === */
+    /** block containing the QC for the highest block having one */
+    block_t bqc;
+    block_t bexec;                            /**< last executed block */
+    uint32_t vheight;          /**< height of the block last voted for */
+    /* === auxilliary variables === */
+    privkey_bt priv_key;            /**< private key for signing votes */
+    std::set<block_t, BlockHeightCmp> tails;   /**< set of tail blocks */
+    ReplicaConfig config;                   /**< replica configuration */
+    /* === async event queues === */
+    std::unordered_map<block_t, promise_t> qc_waiting;
+    promise_t propose_waiting;
+
+    block_t sanity_check_delivered(const uint256_t &blk_hash);
+    void sanity_check_delivered(const block_t &blk);
+    void check_commit(const block_t &_bqc);
+    bool update(const uint256_t &bqc_hash);
+    void on_qc_finish(const block_t &blk);
+    void on_propose_(const block_t &blk);
+
+    protected:
+    ReplicaID id;                  /**< identity of the replica itself */
+    const int32_t parent_limit;         /**< maximum number of parents */
+
+    public:
+    BoxObj<EntityStorage> storage;
+
+    HotStuffCore(ReplicaID id,
+                privkey_bt &&priv_key,
+                int32_t parent_limit);
+    virtual ~HotStuffCore() = default;
+
+    /* Inputs of the state machine triggered by external events, should called
+     * by the class user, with proper invariants. */
+
+    /** Call to initialize the protocol, should be called once before all other
+     * functions. */
+    void on_init(uint32_t nfaulty) { config.nmajority = 2 * nfaulty + 1; }
+
+    /** Call to deliver a block.
+     * A block is only delivered if itself is fetched, the block for the
+     * contained qc is fetched and all parents are delivered. The user should
+     * always ensure this invariant. The invalid blocks will be dropped by this
+     * function.
+     * @return true if valid */
+    bool on_deliver_blk(const block_t &blk);
+
+    /** Call upon the delivery of a proposal message.
+     * The block mentioned in the message should be already delivered. */
+    void on_receive_proposal(const Proposal &prop);
+
+    /** Call upon the delivery of a vote message.
+     * The block mentioned in the message should be already delivered. */
+    void on_receive_vote(const Vote &vote);
+
+    /** Call to submit new commands to be decided (executed). */
+    void on_propose(const std::vector<command_t> &cmds);
+
+    /* Functions required to construct concrete instances for abstract classes.
+     * */
+
+    /* Outputs of the state machine triggering external events.  The virtual
+     * functions should be implemented by the user to specify the behavior upon
+     * the events. */
+    protected:
+    /** Called by HotStuffCore upon the decision being made for cmd. */
+    virtual void do_decide(const command_t &cmd) = 0;
+    /** Called by HotStuffCore upon broadcasting a new proposal.
+     * The user should send the proposal message to all replicas except for
+     * itself. */
+    virtual void do_broadcast_proposal(const Proposal &prop) = 0;
+    /** Called upon sending out a new vote to the next proposer.  The user
+     * should send the vote message to a *good* proposer to have good liveness,
+     * while safety is always guaranteed by HotStuffCore. */
+    virtual void do_vote(ReplicaID last_proposer, const Vote &vote) = 0;
+
+    /* The user plugs in the detailed instances for those
+     * polymorphic data types. */
+    public:
+    /** Create a partial certificate that proves the vote for a block. */
+    virtual part_cert_bt create_part_cert(const PrivKey &priv_key, const uint256_t &blk_hash) = 0;
+    /** Create a partial certificate from its seralized form. */
+    virtual part_cert_bt parse_part_cert(DataStream &s) = 0;
+    /** Create a quorum certificate that proves 2f+1 votes for a block. */
+    virtual quorum_cert_bt create_quorum_cert(const uint256_t &blk_hash) = 0;
+    /** Create a quorum certificate from its serialized form. */
+    virtual quorum_cert_bt parse_quorum_cert(DataStream &s) = 0;
+    /** Create a command object from its serialized form. */
+    virtual command_t parse_cmd(DataStream &s) = 0;
+
+    public:
+    /** Add a replica to the current configuration. This should only be called
+     * before running HotStuffCore protocol. */
+    void add_replica(ReplicaID rid, const NetAddr &addr, pubkey_bt &&pub_key);
+    /** Try to prune blocks lower than last committed height - staleness. */
+    void prune(uint32_t staleness);
+
+    /* PaceMaker can use these functions to monitor the core protocol state
+     * transition */
+    /** Get a promise resolved when the block gets a QC. */
+    promise_t async_qc_finish(const block_t &blk);
+    /** Get a promise resolved when a new block is proposed. */
+    promise_t async_wait_propose();
+
+    /* Other useful functions */
+    block_t get_genesis() { return b0; }
+    const ReplicaConfig &get_config() { return config; }
+    int8_t get_cmd_decision(const uint256_t &cmd_hash);
+    ReplicaID get_id() { return id; }
+    operator std::string () const;
+};
+
+/** Abstraction for proposal messages. */
+struct Proposal: public Serializable {
+    ReplicaID proposer;
+    /** hash for the block containing the highest QC */
+    uint256_t bqc_hash;
+    /** block being proposed */
+    block_t blk;
+
+    /** handle of the core object to allow polymorphism. The user should use
+     * a pointer to the object of the class derived from HotStuffCore */
+    HotStuffCore *hsc;
+
+    Proposal(HotStuffCore *hsc): blk(nullptr), hsc(hsc) {}
+    Proposal(ReplicaID proposer,
+            const uint256_t &bqc_hash,
+            block_t &blk,
+            HotStuffCore *hsc):
+        proposer(proposer),
+        bqc_hash(bqc_hash),
+        blk(blk), hsc(hsc) {}
+
+    void serialize(DataStream &s) const override {
+        s << proposer
+          << bqc_hash
+          << *blk;
+    }
+
+    void unserialize(DataStream &s) override {
+        assert(hsc != nullptr);
+        s >> proposer
+          >> bqc_hash;
+        Block _blk;
+        _blk.unserialize(s, hsc);
+        blk = hsc->storage->add_blk(std::move(_blk));
+    }
+
+    operator std::string () const {
+        DataStream s;
+        s << "<proposal "
+          << "rid=" << std::to_string(proposer) << " "
+          << "bqc=" << get_hex10(bqc_hash) << " "
+          << "blk=" << get_hex10(blk->get_hash()) << ">";
+        return std::string(std::move(s));
+    }
+};
+
+/** Abstraction for vote messages. */
+struct Vote: public Serializable {
+    ReplicaID voter;
+    /** hash for the block containing the highest QC */
+    uint256_t bqc_hash;
+    /** block being voted */
+    uint256_t blk_hash;
+    /** proof of validity for the vote (nullptr for a negative vote) */
+    part_cert_bt cert;
+    
+    /** handle of the core object to allow polymorphism */
+    HotStuffCore *hsc;
+
+    Vote(HotStuffCore *hsc): cert(nullptr), hsc(hsc) {}
+    Vote(ReplicaID voter,
+        const uint256_t &bqc_hash,
+        const uint256_t &blk_hash,
+        part_cert_bt &&cert,
+        HotStuffCore *hsc):
+        voter(voter),
+        bqc_hash(bqc_hash),
+        blk_hash(blk_hash),
+        cert(std::move(cert)), hsc(hsc) {}
+
+    Vote(const Vote &other):
+        voter(other.voter),
+        bqc_hash(other.bqc_hash),
+        blk_hash(other.blk_hash),
+        cert(other.cert->clone()),
+        hsc(other.hsc) {}
+
+    Vote(Vote &&other) = default;
+    
+    void serialize(DataStream &s) const override {
+        s << voter
+          << bqc_hash
+          << blk_hash;
+        if (cert == nullptr)
+            s << (uint8_t)0;
+        else
+            s << (uint8_t)1 << *cert;
+    }
+
+    void unserialize(DataStream &s) override {
+        assert(hsc != nullptr);
+        uint8_t has_cert;
+        s >> voter
+          >> bqc_hash
+          >> blk_hash
+          >> has_cert;
+        cert = has_cert ? hsc->parse_part_cert(s) : nullptr;
+    }
+
+    bool verify() const {
+        assert(hsc != nullptr);
+        return cert->verify(hsc->get_config().get_pubkey(voter)) &&
+                cert->get_blk_hash() == blk_hash;
+    }
+
+    operator std::string () const {
+        DataStream s;
+        s << "<vote "
+          << "rid=" << std::to_string(voter) << " "
+          << "bqc=" << get_hex10(bqc_hash) << " "
+          << "blk=" << get_hex10(blk_hash) << " "
+          << "cert=" << (cert ? "yes" : "no") << ">";
+        return std::string(std::move(s));
+    }
+};
+
+/** Abstraction for liveness gadget (oracle). */
+class PaceMaker {
+    public:
+    virtual ~PaceMaker() = default;
+    /** Get a promise resolved when the pace maker thinks it is a *good* time
+     * to issue new commands. When promise is resolved with the ID of itself,
+     * the replica should propose the command, otherwise it will forward the
+     * command to the proposer indicated by the ID. */
+    virtual promise_t beat() = 0;
+    /** Get a promise resolved when the pace maker thinks it is a *good* time
+     * to vote for a block. The promise is resolved with the next proposer's ID
+     * */
+    virtual promise_t next_proposer(ReplicaID last_proposer) = 0;
+};
+
+using pacemaker_bt = BoxObj<PaceMaker>;
+
+/** A pace maker that waits for the qc of the last proposed block. */
+class PaceMakerDummy: public PaceMaker {
+    HotStuffCore *hsc;
+    std::queue<promise_t> pending_beats;
+    block_t last_proposed;
+    bool locked;
+
+    void schedule_next() {
+        if (!pending_beats.empty() && !locked)
+        {
+            auto pm = pending_beats.front();
+            pending_beats.pop();
+            hsc->async_qc_finish(last_proposed).then(
+                    [id = hsc->get_id(), pm]() {
+                pm.resolve(id);
+            });
+            locked = true;
+        }
+    }
+
+    void update_last_proposed() {
+        hsc->async_wait_propose().then([this](block_t blk) {
+            update_last_proposed();
+            last_proposed = blk;
+            locked = false;
+            schedule_next();
+        });
+    }
+
+    public:
+    PaceMakerDummy(HotStuffCore *hsc):
+            hsc(hsc),
+            last_proposed(hsc->get_genesis()),
+            locked(false) {
+        update_last_proposed();
+    }
+
+    promise_t beat() override {
+        promise_t pm;
+        pending_beats.push(pm);
+        schedule_next();
+        return pm;
+    }
+
+    promise_t next_proposer(ReplicaID last_proposer) override {
+        return promise_t([last_proposer](promise_t &pm) {
+            pm.resolve(last_proposer);
+        });
+    }
+};
+
+/** Network message format for HotStuff. */
+struct MsgHotStuff: public salticidae::MsgBase<> {
+    using MsgBase::MsgBase;
+    void gen_propose(const Proposal &);
+    void parse_propose(Proposal &) const;
+
+    void gen_vote(const Vote &);
+    void parse_vote(Vote &) const;
+
+    void gen_qfetchblk(const std::vector<uint256_t> &blk_hashes);
+    void parse_qfetchblk(std::vector<uint256_t> &blk_hashes) const;
+
+    void gen_rfetchblk(const std::vector<block_t> &blks);
+    void parse_rfetchblk(std::vector<block_t> &blks, HotStuffCore *hsc) const;
+};
+
+using promise::promise_t;
+
+class HotStuffBase;
+
+template<EntityType ent_type>
+class FetchContext: public promise_t {
+    Event timeout;
+    HotStuffBase *hs;
+    MsgHotStuff fetch_msg;
+    const uint256_t ent_hash;
+    std::unordered_set<NetAddr> replica_ids;
+    inline void timeout_cb(evutil_socket_t, short);
+    public:
+    FetchContext(const FetchContext &) = delete;
+    FetchContext &operator=(const FetchContext &) = delete;
+    FetchContext(FetchContext &&other);
+
+    FetchContext(const uint256_t &ent_hash, HotStuffBase *hs);
+    ~FetchContext() {}
+
+    inline void send(const NetAddr &replica_id);
+    inline void reset_timeout();
+    inline void add_replica(const NetAddr &replica_id, bool fetch_now = true);
+};
+
+class BlockDeliveryContext: public promise_t {
+    public:
+    ElapsedTime elapsed;
+    BlockDeliveryContext &operator=(const BlockDeliveryContext &) = delete;
+    BlockDeliveryContext(const BlockDeliveryContext &other):
+        promise_t(static_cast<const promise_t &>(other)),
+        elapsed(other.elapsed) {}
+    BlockDeliveryContext(BlockDeliveryContext &&other):
+        promise_t(static_cast<const promise_t &>(other)),
+        elapsed(std::move(other.elapsed)) {}
+    template<typename Func>
+    BlockDeliveryContext(Func callback): promise_t(callback) {
+        elapsed.start();
+    }
+};
+
+
+/** HotStuff protocol (with network implementation). */
+class HotStuffBase: public HotStuffCore {
+    using BlockFetchContext = FetchContext<ENT_TYPE_BLK>;
+    using CmdFetchContext = FetchContext<ENT_TYPE_CMD>;
+    using conn_t = MsgNetwork<MsgHotStuff>::conn_t;
+
+    friend BlockFetchContext;
+    friend CmdFetchContext;
+
+    protected:
+    /** the binding address in replica network */
+    NetAddr listen_addr;
+    /** the block size */
+    size_t blk_size;
+    /** libevent handle */
+    EventContext eb;
+    pacemaker_bt pmaker;
+
+    private:
+    /** whether libevent handle is owned by itself */
+    bool eb_loop;
+    /** network stack */
+    PeerNetwork<MsgHotStuff> pn;
+#ifdef HOTSTUFF_ENABLE_BLK_PROFILE
+    BlockProfiler blk_profiler;
+#endif
+    /* queues for async tasks */
+    std::unordered_map<const uint256_t, BlockFetchContext> blk_fetch_waiting;
+    std::unordered_map<const uint256_t, BlockDeliveryContext> blk_delivery_waiting;
+    std::unordered_map<const uint256_t, CmdFetchContext> cmd_fetch_waiting;
+    std::unordered_map<const uint256_t, promise_t> decision_waiting;
+    std::queue<command_t> cmd_pending;
+
+    /* statistics */
+    uint64_t fetched;
+    uint64_t delivered;
+    mutable uint64_t nsent;
+    mutable uint64_t nrecv;
+
+    mutable uint32_t part_parent_size;
+    mutable uint32_t part_fetched;
+    mutable uint32_t part_delivered;
+    mutable uint32_t part_decided;
+    mutable uint32_t part_gened;
+    mutable double part_delivery_time;
+    mutable double part_delivery_time_min;
+    mutable double part_delivery_time_max;
+    mutable std::unordered_map<const NetAddr, uint32_t> part_fetched_replica;
+
+    void on_fetch_cmd(const command_t &cmd);
+    void on_fetch_blk(const block_t &blk);
+    void on_deliver_blk(const block_t &blk);
+
+    /** deliver consensus message: <propose> */
+    inline void propose_handler(const MsgHotStuff &, conn_t);
+    /** deliver consensus message: <vote> */
+    inline void vote_handler(const MsgHotStuff &, conn_t);
+    /** fetches full block data */
+    inline void query_fetch_blk_handler(const MsgHotStuff &, conn_t);
+    /** receives a block */
+    inline void resp_fetch_blk_handler(const MsgHotStuff &, conn_t);
+
+    void do_broadcast_proposal(const Proposal &) override;
+    void do_vote(ReplicaID, const Vote &) override;
+    void do_decide(const command_t &) override;
+
+    public:
+    HotStuffBase(uint32_t blk_size,
+            int32_t parent_limit,
+            ReplicaID rid,
+            privkey_bt &&priv_key,
+            NetAddr listen_addr,
+            EventContext eb = EventContext(),
+            pacemaker_bt pmaker = nullptr);
+
+    ~HotStuffBase();
+
+    /* the API for HotStuffBase */
+
+    /* Submit the command to be decided. */
+    void add_command(command_t cmd) {
+        cmd_pending.push(storage->add_cmd(cmd));
+        if (cmd_pending.size() >= blk_size)
+        {
+            std::vector<command_t> cmds;
+            for (uint32_t i = 0; i < blk_size; i++)
+            {
+                cmds.push_back(cmd_pending.front());
+                cmd_pending.pop();
+            }
+            pmaker->beat().then([this, cmds = std::move(cmds)]() {
+                on_propose(cmds);
+            });
+        }
+    }
+
+    void add_replica(ReplicaID idx, const NetAddr &addr, pubkey_bt &&pub_key);
+    void start(bool eb_loop = false);
+
+    size_t size() const { return pn.all_peers().size(); }
+    void print_stat() const;
+
+    /* Helper functions */
+    /** Returns a promise resolved (with command_t cmd) when Command is fetched. */
+    promise_t async_fetch_cmd(const uint256_t &cmd_hash, const NetAddr *replica_id, bool fetch_now = true);
+    /** Returns a promise resolved (with block_t blk) when Block is fetched. */
+    promise_t async_fetch_blk(const uint256_t &blk_hash, const NetAddr *replica_id, bool fetch_now = true);
+    /** Returns a promise resolved (with block_t blk) when Block is delivered (i.e. prefix is fetched). */
+    promise_t async_deliver_blk(const uint256_t &blk_hash,  const NetAddr &replica_id);
+    /** Returns a promise resolved (with command_t cmd) when Command is decided. */
+    promise_t async_decide(const uint256_t &cmd_hash);
+};
+
+/** HotStuff protocol (templated by cryptographic implementation). */
+template<typename PrivKeyType = PrivKeyDummy,
+        typename PubKeyType = PubKeyDummy,
+        typename PartCertType = PartCertDummy,
+        typename QuorumCertType = QuorumCertDummy>
+class HotStuff: public HotStuffBase {
+    using HotStuffBase::HotStuffBase;
+    protected:
+
+    part_cert_bt create_part_cert(const PrivKey &priv_key, const uint256_t &blk_hash) override {
+        return new PartCertType(
+                    static_cast<const PrivKeyType &>(priv_key),
+                    blk_hash);
+    }
+
+    part_cert_bt parse_part_cert(DataStream &s) override {
+        PartCert *pc = new PartCertType();
+        s >> *pc;
+        return pc;
+    }
+
+    quorum_cert_bt create_quorum_cert(const uint256_t &blk_hash) override {
+        return new QuorumCertType(get_config(), blk_hash);
+    }
+
+    quorum_cert_bt parse_quorum_cert(DataStream &s) override {
+        QuorumCert *qc = new QuorumCertType();
+        s >> *qc;
+        return qc;
+    }
+
+    public:
+    HotStuff(uint32_t blk_size,
+            int32_t parent_limit,
+            ReplicaID rid,
+            const bytearray_t &raw_privkey,
+            NetAddr listen_addr,
+            EventContext eb = nullptr):
+        HotStuffBase(blk_size,
+                    parent_limit,
+                    rid,
+                    new PrivKeyType(raw_privkey),
+                    listen_addr,
+                    eb) {}
+
+    void add_replica(ReplicaID idx, const NetAddr &addr, const bytearray_t &pubkey_raw) {
+        DataStream s(pubkey_raw);
+        HotStuffBase::add_replica(idx, addr, new PubKeyType(pubkey_raw));
+    }
+};
+
+using HotStuffNoSig = HotStuff<>;
+using HotStuffSecp256k1 = HotStuff<PrivKeySecp256k1, PubKeySecp256k1,
+                                    PartCertSecp256k1, QuorumCertSecp256k1>;
+
+template<EntityType ent_type>
+FetchContext<ent_type>::FetchContext(FetchContext && other):
+        promise_t(static_cast<const promise_t &>(other)),
+        hs(other.hs),
+        fetch_msg(std::move(other.fetch_msg)),
+        ent_hash(other.ent_hash),
+        replica_ids(std::move(other.replica_ids)) {
+    other.timeout.del();
+    timeout = Event(hs->eb, -1, 0,
+            std::bind(&FetchContext::timeout_cb, this, _1, _2));
+    reset_timeout();
+}
+
+template<>
+inline void FetchContext<ENT_TYPE_CMD>::timeout_cb(evutil_socket_t, short) {
+    HOTSTUFF_LOG_WARN("cmd fetching %.10s timeout", get_hex(ent_hash).c_str());
+    for (const auto &replica_id: replica_ids)
+        send(replica_id);
+    reset_timeout();
+}
+
+template<>
+inline void FetchContext<ENT_TYPE_BLK>::timeout_cb(evutil_socket_t, short) {
+    HOTSTUFF_LOG_WARN("block fetching %.10s timeout", get_hex(ent_hash).c_str());
+    for (const auto &replica_id: replica_ids)
+        send(replica_id);
+    reset_timeout();
+}
+
+template<EntityType ent_type>
+FetchContext<ent_type>::FetchContext(
+                                const uint256_t &ent_hash, HotStuffBase *hs):
+            promise_t([](promise_t){}),
+            hs(hs), ent_hash(ent_hash) {
+    fetch_msg.gen_qfetchblk(std::vector<uint256_t>{ent_hash});
+
+    timeout = Event(hs->eb, -1, 0,
+            std::bind(&FetchContext::timeout_cb, this, _1, _2));
+    reset_timeout();
+}
+
+template<EntityType ent_type>
+void FetchContext<ent_type>::send(const NetAddr &replica_id) {
+    hs->part_fetched_replica[replica_id]++;
+    hs->pn.send_msg(fetch_msg, replica_id);
+}
+
+template<EntityType ent_type>
+void FetchContext<ent_type>::reset_timeout() {
+    timeout.add_with_timeout(salticidae::gen_rand_timeout(ent_waiting_timeout));
+}
+
+template<EntityType ent_type>
+void FetchContext<ent_type>::add_replica(const NetAddr &replica_id, bool fetch_now) {
+    if (replica_ids.empty() && fetch_now)
+        send(replica_id);
+    replica_ids.insert(replica_id);
+}
+
+}
+
+#endif
diff --git a/include/hotstuff/crypto.h b/include/hotstuff/crypto.h
new file mode 100644
index 0000000..2fbf745
--- /dev/null
+++ b/include/hotstuff/crypto.h
@@ -0,0 +1,386 @@
+#ifndef _HOTSTUFF_CRYPTO_H
+#define _HOTSTUFF_CRYPTO_H
+
+#include "salticidae/crypto.h"
+#include "salticidae/ref.h"
+#include "secp256k1.h"
+#include <openssl/rand.h>
+#include "type.h"
+
+using salticidae::RcObj;
+using salticidae::BoxObj;
+
+namespace hotstuff {
+
+using salticidae::SHA256;
+
+class PubKey: public Serializable, Cloneable {
+    public:
+    virtual ~PubKey() = default;
+    virtual PubKey *clone() override = 0;
+};
+
+using pubkey_bt = BoxObj<PubKey>;
+
+class PrivKey: public Serializable {
+    public:
+    virtual ~PrivKey() = default;
+    virtual pubkey_bt get_pubkey() const = 0;
+    virtual void from_rand() = 0;
+};
+
+using privkey_bt = BoxObj<PrivKey>;
+
+class PartCert: public Serializable, public Cloneable {
+    public:
+    virtual ~PartCert() = default;
+    virtual bool verify(const PubKey &pubkey) = 0;
+    virtual const uint256_t &get_blk_hash() const = 0;
+    virtual PartCert *clone() override = 0;
+};
+
+class ReplicaConfig;
+
+class QuorumCert: public Serializable, public Cloneable {
+    public:
+    virtual ~QuorumCert() = default;
+    virtual void add_part(ReplicaID replica, const PartCert &pc) = 0;
+    virtual void compute() = 0;
+    virtual bool verify(const ReplicaConfig &config) = 0;
+    virtual const uint256_t &get_blk_hash() const = 0;
+    virtual QuorumCert *clone() override = 0;
+};
+
+using part_cert_bt = BoxObj<PartCert>;
+using quorum_cert_bt = BoxObj<QuorumCert>;
+
+class PubKeyDummy: public PubKey {
+    PubKeyDummy *clone() override { return new PubKeyDummy(*this); }
+    void serialize(DataStream &) const override {}
+    void unserialize(DataStream &) override {}
+};
+
+class PrivKeyDummy: public PrivKey {
+    pubkey_bt get_pubkey() const override { return new PubKeyDummy(); }
+    void serialize(DataStream &) const override {}
+    void unserialize(DataStream &) override {}
+    void from_rand() override {}
+};
+
+class PartCertDummy: public PartCert {
+    uint256_t blk_hash;
+    public:
+    PartCertDummy() {}
+    PartCertDummy(const uint256_t &blk_hash):
+        blk_hash(blk_hash) {}
+
+    void serialize(DataStream &s) const override {
+        s << (uint32_t)0 << blk_hash;
+    }
+
+    void unserialize(DataStream &s) override {
+        uint32_t tmp;
+        s >> tmp >> blk_hash;
+    }
+
+    PartCert *clone() override {
+        return new PartCertDummy(blk_hash);
+    }
+
+    bool verify(const PubKey &) override { return true; }
+
+    const uint256_t &get_blk_hash() const override { return blk_hash; }
+};
+
+class QuorumCertDummy: public QuorumCert {
+    uint256_t blk_hash;
+    public:
+    QuorumCertDummy() {}
+    QuorumCertDummy(const ReplicaConfig &, const uint256_t &blk_hash):
+        blk_hash(blk_hash) {}
+
+    void serialize(DataStream &s) const override {
+        s << (uint32_t)1 << blk_hash;
+    }
+
+    void unserialize(DataStream &s) override {
+        uint32_t tmp;
+        s >> tmp >> blk_hash;
+    }
+
+    QuorumCert *clone() override {
+        return new QuorumCertDummy(*this);
+    }
+
+    void add_part(ReplicaID, const PartCert &) override {}
+    void compute() override {}
+    bool verify(const ReplicaConfig &) override { return true; }
+
+    const uint256_t &get_blk_hash() const override { return blk_hash; }
+};
+
+
+class Secp256k1Context {
+    secp256k1_context *ctx;
+    friend class PubKeySecp256k1;
+    friend class SigSecp256k1;
+    public:
+    Secp256k1Context(bool sign = false):
+        ctx(secp256k1_context_create(
+            sign ? SECP256K1_CONTEXT_SIGN :
+                    SECP256K1_CONTEXT_VERIFY)) {}
+
+    Secp256k1Context(const Secp256k1Context &) = delete;
+
+    Secp256k1Context(Secp256k1Context &&other): ctx(other.ctx) {
+        other.ctx = nullptr;
+    }
+
+    ~Secp256k1Context() {
+        if (ctx) secp256k1_context_destroy(ctx);
+    }
+};
+
+using secp256k1_context_t = RcObj<Secp256k1Context>;
+
+extern secp256k1_context_t secp256k1_default_sign_ctx;
+extern secp256k1_context_t secp256k1_default_verify_ctx;
+
+class PrivKeySecp256k1;
+
+class PubKeySecp256k1: public PubKey {
+    static const auto _olen = 33;
+    friend class SigSecp256k1;
+    secp256k1_pubkey data;
+    secp256k1_context_t ctx;
+
+    public:
+    PubKeySecp256k1(const secp256k1_context_t &ctx =
+                            secp256k1_default_sign_ctx):
+        PubKey(), ctx(ctx) {}
+    
+    PubKeySecp256k1(const bytearray_t &raw_bytes,
+                    const secp256k1_context_t &ctx =
+                            secp256k1_default_sign_ctx):
+        PubKeySecp256k1(ctx) { from_bytes(raw_bytes); }
+
+    inline PubKeySecp256k1(const PrivKeySecp256k1 &priv_key,
+                            const secp256k1_context_t &ctx =
+                                    secp256k1_default_sign_ctx);
+
+    void serialize(DataStream &s) const override {
+        static uint8_t output[_olen];
+        size_t olen = _olen;
+        (void)secp256k1_ec_pubkey_serialize(
+                ctx->ctx, (unsigned char *)output,
+                &olen, &data, SECP256K1_EC_COMPRESSED);
+        s.put_data(output, output + _olen);
+    }
+
+    void unserialize(DataStream &s) override {
+        static const auto _exc = std::invalid_argument("ill-formed public key");
+        try {
+            if (!secp256k1_ec_pubkey_parse(
+                    ctx->ctx, &data, s.get_data_inplace(_olen), _olen))
+                throw _exc;
+        } catch (std::ios_base::failure &) {
+            throw _exc;
+        }
+    }
+
+    PubKeySecp256k1 *clone() override {
+        return new PubKeySecp256k1(*this);
+    }
+};
+
+class PrivKeySecp256k1: public PrivKey {
+    static const auto nbytes = 32;
+    friend class PubKeySecp256k1;
+    friend class SigSecp256k1;
+    uint8_t data[nbytes];
+    secp256k1_context_t ctx;
+
+    public:
+    PrivKeySecp256k1(const secp256k1_context_t &ctx =
+                            secp256k1_default_sign_ctx):
+        PrivKey(), ctx(ctx) {}
+
+    PrivKeySecp256k1(const bytearray_t &raw_bytes,
+                     const secp256k1_context_t &ctx =
+                            secp256k1_default_sign_ctx):
+        PrivKeySecp256k1(ctx) { from_bytes(raw_bytes); }
+
+    void serialize(DataStream &s) const override {
+        s.put_data(data, data + nbytes);
+    }
+
+    void unserialize(DataStream &s) override {
+        static const auto _exc = std::invalid_argument("ill-formed private key");
+        try {
+            memmove(data, s.get_data_inplace(nbytes), nbytes);
+        } catch (std::ios_base::failure &) {
+            throw _exc;
+        }
+    }
+
+    void from_rand() override {
+        if (!RAND_bytes(data, nbytes))
+            throw std::runtime_error("cannot get rand bytes from openssl");
+    }
+
+    inline pubkey_bt get_pubkey() const override;
+};
+
+pubkey_bt PrivKeySecp256k1::get_pubkey() const {
+    return new PubKeySecp256k1(*this, ctx);
+}
+
+PubKeySecp256k1::PubKeySecp256k1(
+        const PrivKeySecp256k1 &priv_key,
+        const secp256k1_context_t &ctx): PubKey(), ctx(ctx) {
+    if (!secp256k1_ec_pubkey_create(ctx->ctx, &data, priv_key.data))
+        throw std::invalid_argument("invalid secp256k1 private key");
+}
+
+class SigSecp256k1: public Serializable {
+    secp256k1_ecdsa_signature data;
+    secp256k1_context_t ctx;
+
+    void check_msg_length(const bytearray_t &msg) {
+        if (msg.size() != 32)
+            throw std::invalid_argument("the message should be 32-bytes");
+    }
+
+    public:
+    SigSecp256k1(const secp256k1_context_t &ctx =
+                        secp256k1_default_sign_ctx):
+        Serializable(), ctx(ctx) {}
+    SigSecp256k1(const uint256_t &digest,
+                const PrivKeySecp256k1 &priv_key,
+                secp256k1_context_t &ctx =
+                        secp256k1_default_sign_ctx):
+        Serializable(), ctx(ctx) {
+        sign(digest, priv_key);