Pretty sure it works but kosync is down right now even on my other devices

lib/KOReaderSync/KOReaderCredentialStore.cpp

@@ -0,0 +1,111 @@
+#include "KOReaderCredentialStore.h"
+
+#include <HardwareSerial.h>
+#include <MD5Builder.h>
+#include <SDCardManager.h>
+#include <Serialization.h>
+
+// Initialize the static instance
+KOReaderCredentialStore KOReaderCredentialStore::instance;
+
+namespace {
+// File format version
+constexpr uint8_t KOREADER_FILE_VERSION = 1;
+
+// KOReader credentials file path
+constexpr char KOREADER_FILE[] = "/.crosspoint/koreader.bin";
+
+// Obfuscation key - "KOReader" in ASCII
+// This is NOT cryptographic security, just prevents casual file reading
+constexpr uint8_t OBFUSCATION_KEY[] = {0x4B, 0x4F, 0x52, 0x65, 0x61, 0x64, 0x65, 0x72};
+constexpr size_t KEY_LENGTH = sizeof(OBFUSCATION_KEY);
+}  // namespace
+
+void KOReaderCredentialStore::obfuscate(std::string& data) const {
+  for (size_t i = 0; i < data.size(); i++) {
+    data[i] ^= OBFUSCATION_KEY[i % KEY_LENGTH];
+  }
+}
+
+bool KOReaderCredentialStore::saveToFile() const {
+  // Make sure the directory exists
+  SdMan.mkdir("/.crosspoint");
+
+  FsFile file;
+  if (!SdMan.openFileForWrite("KRS", KOREADER_FILE, file)) {
+    return false;
+  }
+
+  // Write header
+  serialization::writePod(file, KOREADER_FILE_VERSION);
+
+  // Write username (plaintext - not particularly sensitive)
+  serialization::writeString(file, username);
+  Serial.printf("[%lu] [KRS] Saving username: %s\n", millis(), username.c_str());
+
+  // Write password (obfuscated)
+  std::string obfuscatedPwd = password;
+  obfuscate(obfuscatedPwd);
+  serialization::writeString(file, obfuscatedPwd);
+
+  file.close();
+  Serial.printf("[%lu] [KRS] Saved KOReader credentials to file\n", millis());
+  return true;
+}
+
+bool KOReaderCredentialStore::loadFromFile() {
+  FsFile file;
+  if (!SdMan.openFileForRead("KRS", KOREADER_FILE, file)) {
+    Serial.printf("[%lu] [KRS] No credentials file found\n", millis());
+    return false;
+  }
+
+  // Read and verify version
+  uint8_t version;
+  serialization::readPod(file, version);
+  if (version != KOREADER_FILE_VERSION) {
+    Serial.printf("[%lu] [KRS] Unknown file version: %u\n", millis(), version);
+    file.close();
+    return false;
+  }
+
+  // Read username
+  serialization::readString(file, username);
+
+  // Read and deobfuscate password
+  serialization::readString(file, password);
+  obfuscate(password);  // XOR is symmetric, so same function deobfuscates
+
+  file.close();
+  Serial.printf("[%lu] [KRS] Loaded KOReader credentials for user: %s\n", millis(), username.c_str());
+  return true;
+}
+
+void KOReaderCredentialStore::setCredentials(const std::string& user, const std::string& pass) {
+  username = user;
+  password = pass;
+  Serial.printf("[%lu] [KRS] Set credentials for user: %s\n", millis(), user.c_str());
+}
+
+std::string KOReaderCredentialStore::getMd5Password() const {
+  if (password.empty()) {
+    return "";
+  }
+
+  // Calculate MD5 hash of password using ESP32's MD5Builder
+  MD5Builder md5;
+  md5.begin();
+  md5.add(password.c_str());
+  md5.calculate();
+
+  return md5.toString().c_str();
+}
+
+bool KOReaderCredentialStore::hasCredentials() const { return !username.empty() && !password.empty(); }
+
+void KOReaderCredentialStore::clearCredentials() {
+  username.clear();
+  password.clear();
+  saveToFile();
+  Serial.printf("[%lu] [KRS] Cleared KOReader credentials\n", millis());
+}