hash: add support for SHA256 public key fingerprints

include/opendht/crypto.h

@@ -83,6 +83,7 @@ struct OPENDHT_PUBLIC PublicKey
     PublicKey& operator=(PublicKey&& o) noexcept;
 
     InfoHash getId() const;
+    PkId getLongId() const;
     bool checkSignature(const Blob& data, const Blob& signature) const;
     Blob encrypt(const Blob&) const;
 
@@ -350,6 +351,7 @@ struct OPENDHT_PUBLIC Certificate {
 
     /** Same as getPublicKey().getId() */
     InfoHash getId() const;
+    PkId getLongId() const;
 
     /** Read certificate Common Name (CN) */
     std::string getName() const;

include/opendht/infohash.h

@@ -50,6 +50,51 @@ typedef uint16_t in_port_t;
 
 namespace dht {
 
+using byte = uint8_t;
+
+template <size_t N>
+class OPENDHT_PUBLIC Hash
+{
+public:
+    Hash() {
+        data_.fill(0);
+    }
+    Hash(const msgpack::object& o) {
+        msgpack_unpack(o);
+    }
+    byte* data() {
+        return data_.data();
+    }
+    const byte* data() const {
+        return data_.data();
+    }
+    constexpr size_t size() const { return data_.size(); }
+    explicit operator bool() const { return std::any_of(data_.begin(), data_.end(), [](byte _b) { return _b != 0; }); }
+    bool operator==(Hash const& _c) const { return data_ == _c.data_; }
+    bool operator!=(Hash const& _c) const { return data_ != _c.data_; }
+    bool operator<(Hash const& _c) const { for (unsigned i = 0; i < N; ++i) if (data_[i] < _c.data_[i]) return true; else if (data_[i] > _c.data_[i]) return false; return false; }
+    bool operator>=(Hash const& _c) const { return !operator<(_c); }
+    bool operator<=(Hash const& _c) const { return operator==(_c) || operator<(_c); }
+    bool operator>(Hash const& _c) const { return !operator<=(_c); }
+    template <typename Packer>
+    void msgpack_pack(Packer& pk) const
+    {
+        pk.pack_bin(N);
+        pk.pack_bin_body((char*)data_.data(), N);
+    }
+    void msgpack_unpack(msgpack::object o) {
+        if (o.type != msgpack::type::BIN or o.via.bin.size != N)
+            throw msgpack::type_error();
+        std::copy_n(o.via.bin.ptr, N, data_.data());
+    }
+
+private:
+    std::array<byte, N> data_;
+};
+
+using h256 = Hash<32>;
+using PkId = h256;
+
 /**
  * Represents an InfoHash.
  * An InfoHash is a byte array of HASH_LEN bytes.

src/crypto.cpp

@@ -517,6 +517,16 @@ PublicKey::getId() const
     return id;
 }
 
+PkId
+PublicKey::getLongId() const
+{
+    PkId h;
+    size_t sz = h.size();
+    if (gnutls_pubkey_get_key_id(pk, GNUTLS_KEYID_USE_SHA256, h.data(), &sz) != GNUTLS_E_SUCCESS || sz != h.size())
+        return {};
+    return h;
+}
+
 Certificate::Certificate(const Blob& certData) : cert(nullptr)
 {
     unpack(certData.data(), certData.size());
@@ -621,6 +631,18 @@ Certificate::getId() const
     return id;
 }
 
+PkId
+Certificate::getLongId() const
+{
+    if (not cert)
+        return {};
+    PkId id;
+    size_t sz = id.size();
+    if (gnutls_x509_crt_get_key_id(cert, GNUTLS_KEYID_USE_SHA256, id.data(), &sz) != GNUTLS_E_SUCCESS || sz != id.size())
+        throw CryptoException("Can't get certificate public key ID.");
+    return id;
+}
+
 static std::string
 getDN(gnutls_x509_crt_t cert, const char* oid, bool issuer = false)
 {