core: move away from db towards hash-based auth

src/core/Challenge.cpp

@@ -0,0 +1,62 @@
+#include "Challenge.hpp"
+
+#include "Crypto.hpp"
+
+#include <fmt/format.h>
+#include <glaze/glaze.hpp>
+
+constexpr const uint64_t CHALLENGE_VERSION = 1;
+
+CChallenge::CChallenge(const std::string& fingerprint, const std::string& challenge, int difficulty) :
+    m_fingerprint(fingerprint), m_challenge(challenge), m_difficulty(difficulty) {
+    std::string toSign = getSigString();
+
+    m_sig = g_pCrypto->sign(toSign);
+
+    m_valid = true;
+}
+
+CChallenge::CChallenge(const std::string& jsonResponse) {
+    auto json = glz::read_json<SChallengeJSON>(jsonResponse);
+
+    if (!json.has_value())
+        return;
+
+    SChallengeJSON s = json.value();
+
+    m_challenge   = s.challenge;
+    m_fingerprint = s.fingerprint;
+    m_sig         = s.sig;
+
+    if (!g_pCrypto->verifySignature(getSigString(), m_sig))
+        return;
+
+    const auto SHA = g_pCrypto->sha256(m_challenge + std::to_string(s.solution));
+
+    for (size_t i = 0; i < m_difficulty; ++i) {
+        if (SHA.at(i) != '0')
+            return;
+    }
+
+    m_valid = true;
+}
+
+std::string CChallenge::fingerprint() const {
+    return m_fingerprint;
+}
+
+std::string CChallenge::challenge() const {
+    return m_challenge;
+}
+
+std::string CChallenge::signature() const {
+    return m_sig;
+}
+
+bool CChallenge::valid() const {
+    return m_valid;
+}
+
+std::string CChallenge::getSigString() {
+    return fmt::format("{}-{},{}", CHALLENGE_VERSION, m_fingerprint, m_challenge);
+}