Add app source for F-Droid release (v1.0.43)

Adds the full Android source tree with unit tests, fastlane store metadata and the Gradle wrapper. The archive shipped without gradle-wrapper.jar, so the official Gradle 9.7.1 wrapper jar is included to make ./gradlew work from a fresh clone. .gitignore now also excludes build output and keystores. README gains build instructions and an updated structure tree. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_015g6ECVSKcBG8CJPrqC3G5o
2026-10-06 18:23:20 +00:00
parent 6851ba52ef
commit 6ac5a582db
242 changed files with 54260 additions and 1 deletions
@@ -0,0 +1,108 @@
+package cc.skysparkle.matewave.security
+
+import android.util.Base64
+import java.security.SecureRandom
+import javax.crypto.Cipher
+import javax.crypto.Mac
+import javax.crypto.spec.GCMParameterSpec
+import javax.crypto.spec.SecretKeySpec
+
+/**
+ * Per-session message protection: AES-256-GCM for confidentiality and a truncated
+ * HMAC-SHA256 tag bound to the sender's direction. A sliding window of sequence numbers
+ * rejects replays while tolerating out-of-order delivery.
+ */
+class SessionAuth(private val secret: ByteArray) {
+    private var lastAcceptedSeq = 0
+    private var outgoingSeq = 0
+
+    private val seenInWindow = java.util.TreeSet<Int>()
+
+    fun nextSeq(): Int {
+        outgoingSeq += 1
+        return outgoingSeq
+    }
+
+    fun acceptSeq(seq: Int): Boolean {
+        if (seq <= 0) return false
+        if (seq > lastAcceptedSeq) {
+            lastAcceptedSeq = seq
+            seenInWindow.add(seq)
+
+            while (seenInWindow.isNotEmpty() && seenInWindow.first() < lastAcceptedSeq - REPLAY_WINDOW) {
+                seenInWindow.pollFirst()
+            }
+            return true
+        }
+
+        if (seq < lastAcceptedSeq - REPLAY_WINDOW) return false
+
+        return seenInWindow.add(seq)
+    }
+
+    fun tag(message: String): String? = try {
+        val mac = Mac.getInstance(MAC_ALGORITHM)
+        mac.init(SecretKeySpec(secret, MAC_ALGORITHM))
+        val full = mac.doFinal(message.toByteArray(Charsets.UTF_8))
+        Base64.encodeToString(full.copyOfRange(0, TAG_BYTES), Base64.NO_WRAP)
+    } catch (e: Exception) {
+        null
+    }
+
+    fun verify(message: String, providedTag: String?): Boolean {
+        if (providedTag == null) return false
+        val expected = tag(message) ?: return false
+        if (expected.length != providedTag.length) return false
+        var diff = 0
+        for (i in expected.indices) {
+            diff = diff or (expected[i].code xor providedTag[i].code)
+        }
+        return diff == 0
+    }
+
+    private val encryptionKey: ByteArray by lazy {
+        java.security.MessageDigest.getInstance("SHA-256")
+            .digest(secret + KDF_LABEL)
+    }
+
+    fun encrypt(plaintext: String): String? = try {
+        val nonce = ByteArray(GCM_NONCE_BYTES).also { SecureRandom().nextBytes(it) }
+        val cipher = Cipher.getInstance(CIPHER_ALGORITHM)
+        cipher.init(
+            Cipher.ENCRYPT_MODE,
+            SecretKeySpec(encryptionKey, "AES"),
+            GCMParameterSpec(GCM_TAG_BITS, nonce)
+        )
+        val ciphertext = cipher.doFinal(plaintext.toByteArray(Charsets.UTF_8))
+        Base64.encodeToString(nonce + ciphertext, Base64.NO_WRAP)
+    } catch (e: Exception) {
+        null
+    }
+
+    fun decrypt(payload: String): String? = try {
+        val raw = Base64.decode(payload, Base64.NO_WRAP)
+        if (raw.size <= GCM_NONCE_BYTES) null else {
+            val nonce = raw.copyOfRange(0, GCM_NONCE_BYTES)
+            val ciphertext = raw.copyOfRange(GCM_NONCE_BYTES, raw.size)
+            val cipher = Cipher.getInstance(CIPHER_ALGORITHM)
+            cipher.init(
+                Cipher.DECRYPT_MODE,
+                SecretKeySpec(encryptionKey, "AES"),
+                GCMParameterSpec(GCM_TAG_BITS, nonce)
+            )
+            String(cipher.doFinal(ciphertext), Charsets.UTF_8)
+        }
+    } catch (e: Exception) {
+        null
+    }
+
+    private companion object {
+        const val MAC_ALGORITHM = "HmacSHA256"
+        const val TAG_BYTES = 12
+        const val CIPHER_ALGORITHM = "AES/GCM/NoPadding"
+        const val GCM_NONCE_BYTES = 12
+        const val GCM_TAG_BITS = 128
+        const val REPLAY_WINDOW = 256
+        val KDF_LABEL = "chessapp-session-aes-gcm-v1".toByteArray(Charsets.UTF_8)
+    }
+}