Move sync classes to uhabits-core

android/uhabits-core/src/main/java/org/isoron/uhabits/core/ui/screens/sync/SyncBehavior.kt

@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2016-2020 Álinson Santos Xavier <isoron@gmail.com>
+ *
+ * This file is part of Loop Habit Tracker.
+ *
+ * Loop Habit Tracker is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version.
+ *
+ * Loop Habit Tracker is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.isoron.uhabits.core.ui.screens.sync
+
+import org.isoron.uhabits.core.preferences.*
+import org.isoron.uhabits.sync.*
+
+class SyncBehavior(
+        val screen: Screen,
+        val preferences: Preferences,
+        val server: AbstractSyncServer,
+) {
+    suspend fun onResume() {
+        if (preferences.syncKey.isBlank()) {
+            register()
+        } else {
+            displayCurrentKey()
+        }
+    }
+
+    suspend fun displayCurrentKey() {
+        screen.showLink("https://loophabits.org/sync/${preferences.syncKey}#${preferences.encryptionKey}")
+    }
+
+    suspend fun register() {
+        screen.showLoadingScreen()
+        try {
+            val syncKey = server.register()
+            val encKey = EncryptionKey.generate()
+            preferences.enableSync(syncKey, encKey.base64)
+            displayCurrentKey()
+        } catch (e: Exception) {
+            screen.logError("Unexpected exception $e")
+            screen.showErrorScreen()
+        }
+    }
+
+    interface Screen {
+        suspend fun showLoadingScreen()
+        suspend fun showErrorScreen()
+        suspend fun showLink(link: String)
+        fun logError(msg: String)
+    }
+}

android/uhabits-core/src/main/java/org/isoron/uhabits/sync/AbstractSyncServer.kt

@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2016-2020 Alinson Santos Xavier <git@axavier.org>
+ *
+ * This file is part of Loop Habit Tracker.
+ *
+ * Loop Habit Tracker is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version.
+ *
+ * Loop Habit Tracker is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.isoron.uhabits.sync
+
+interface AbstractSyncServer {
+    /**
+     * Generates and returns a new sync key, which can be used to store and retrive
+     * data.
+     *
+     * @throws ServiceUnavailable If key cannot be generated at this time, for example,
+     *      due to insufficient server resources, temporary server maintenance or network problems.
+     */
+    suspend fun register(): String
+
+    /**
+     * Replaces data for a given sync key.
+     *
+     * @throws KeyNotFoundException If key is not found
+     * @throws EditConflictException If the version of the data provided is not
+     *      exactly the current data version plus one.
+     * @throws ServiceUnavailable If data cannot be put at this time, for example, due
+     *      to insufficient server resources or network problems.
+     */
+    suspend fun put(key: String, newData: SyncData)
+
+    /**
+     * Returns data for a given sync key.
+     *
+     * @throws KeyNotFoundException If key is not found
+     * @throws ServiceUnavailable If data cannot be retrieved at this time, for example, due
+     *      to insufficient server resources or network problems.
+     */
+    suspend fun getData(key: String): SyncData
+
+    /**
+     * Returns the current data version for the given key
+     *
+     * @throws KeyNotFoundException If key is not found
+     * @throws ServiceUnavailable If data cannot be retrieved at this time, for example, due
+     *      to insufficient server resources or network problems.
+     */
+    suspend fun getDataVersion(key: String): Long
+}

android/uhabits-core/src/main/java/org/isoron/uhabits/sync/EncryptionExt.kt

@@ -0,0 +1,134 @@
+/*
+ * Copyright (C) 2016-2020 Álinson Santos Xavier <isoron@gmail.com>
+ *
+ * This file is part of Loop Habit Tracker.
+ *
+ * Loop Habit Tracker is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version.
+ *
+ * Loop Habit Tracker is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+@file:Suppress("UnstableApiUsage")
+
+package org.isoron.uhabits.sync
+
+import com.google.common.io.*
+import kotlinx.coroutines.*
+import org.apache.commons.codec.binary.*
+import java.io.*
+import java.nio.*
+import java.util.zip.*
+import javax.crypto.*
+import javax.crypto.spec.*
+
+/**
+ * Encryption key which can be used with [File.encryptToString], [String.decryptToFile],
+ * [ByteArray.encrypt] and [ByteArray.decrypt].
+ *
+ * To randomly generate a new key, use [EncryptionKey.generate]. To load a key from a
+ * Base64-encoded string, use [EncryptionKey.fromBase64].
+ */
+class EncryptionKey private constructor(
+        val base64: String,
+        val secretKey: SecretKey
+) {
+    companion object {
+
+        fun fromBase64(base64: String): EncryptionKey {
+            val keySpec = SecretKeySpec(base64.decodeBase64(), "AES")
+            return EncryptionKey(base64, keySpec)
+        }
+
+        private fun fromSecretKey(spec: SecretKey): EncryptionKey {
+            val base64 = spec.encoded.encodeBase64().trim()
+            return EncryptionKey(base64, spec)
+        }
+
+        suspend fun generate(): EncryptionKey = Dispatchers.IO {
+            try {
+                val generator = KeyGenerator.getInstance("AES").apply { init(256) }
+                return@IO fromSecretKey(generator.generateKey())
+            } catch (e: Exception) {
+                throw RuntimeException(e)
+            }
+        }
+    }
+}
+
+/**
+ * Encrypts the byte stream using the provided symmetric encryption key.
+ *
+ * The initialization vector (16 bytes) is prepended to the cipher text. To decrypt the result, use
+ * [ByteArray.decrypt], providing the same key.
+ */
+fun ByteArray.encrypt(key: EncryptionKey): ByteArray {
+    val cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING")
+    cipher.init(Cipher.ENCRYPT_MODE, key.secretKey)
+    val encrypted = cipher.doFinal(this)
+    return ByteBuffer
+            .allocate(16 + encrypted.size)
+            .put(cipher.iv)
+            .put(encrypted)
+            .array()
+}
+
+/**
+ * Decrypts a byte stream generated by [ByteArray.encrypt].
+ */
+fun ByteArray.decrypt(key: EncryptionKey): ByteArray {
+    val buffer = ByteBuffer.wrap(this)
+    val iv = ByteArray(16)
+    buffer.get(iv)
+    val encrypted = ByteArray(buffer.remaining())
+    buffer.get(encrypted)
+    val cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING")
+    cipher.init(Cipher.DECRYPT_MODE, key.secretKey, IvParameterSpec(iv))
+    return cipher.doFinal(encrypted)
+}
+
+/**
+ * Takes a string produced by [File.encryptToString], decodes it with Base64, decompresses it with
+ * gzip, decrypts it with the provided key, then writes the output to the specified file.
+ */
+fun String.decryptToFile(key: EncryptionKey, output: File) {
+    val bytes = this.decodeBase64().decrypt(key)
+    ByteArrayInputStream(bytes).use { bytesInputStream ->
+        GZIPInputStream(bytesInputStream).use { gzipInputStream ->
+            FileOutputStream(output).use { fileOutputStream ->
+                ByteStreams.copy(gzipInputStream, fileOutputStream)
+            }
+        }
+    }
+}
+
+/**
+ * Compresses the file with gzip, encrypts it using the the provided key, then returns a string
+ * containing the Base64-encoded cipher bytes.
+ *
+ * To decrypt and decompress the cipher text back into a file, use [String.decryptToFile].
+ */
+fun File.encryptToString(key: EncryptionKey): String {
+    ByteArrayOutputStream().use { bytesOutputStream ->
+        FileInputStream(this).use { inputStream ->
+            GZIPOutputStream(bytesOutputStream).use { gzipOutputStream ->
+                ByteStreams.copy(inputStream, gzipOutputStream)
+                gzipOutputStream.close()
+                val bytes = bytesOutputStream.toByteArray()
+                return bytes.encrypt(key).encodeBase64()
+            }
+        }
+    }
+}
+
+fun ByteArray.encodeBase64(): String = Base64.encodeBase64(this).decodeToString()
+fun String.decodeBase64(): ByteArray = Base64.decodeBase64(this.toByteArray())
+

android/uhabits-core/src/main/java/org/isoron/uhabits/sync/SyncData.kt

@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2016-2020 Alinson Santos Xavier <git@axavier.org>
+ *
+ * This file is part of Loop Habit Tracker.
+ *
+ * Loop Habit Tracker is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version.
+ *
+ * Loop Habit Tracker is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.isoron.uhabits.sync
+
+data class SyncData(
+    val version: Long,
+    val content: String
+)
+
+data class RegisterReponse(val key: String)
+
+data class GetDataVersionResponse(val version: Long)

android/uhabits-core/src/main/java/org/isoron/uhabits/sync/SyncException.kt

@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2016-2020 Alinson Santos Xavier <git@axavier.org>
+ *
+ * This file is part of Loop Habit Tracker.
+ *
+ * Loop Habit Tracker is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version.
+ *
+ * Loop Habit Tracker is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.isoron.uhabits.sync
+
+open class SyncException: RuntimeException()
+
+class KeyNotFoundException: SyncException()
+
+class ServiceUnavailable: SyncException()
+
+class EditConflictException: SyncException()

android/uhabits-core/src/test/java/org/isoron/uhabits/core/sync/EncryptionExtTest.kt

@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2016-2020 Álinson Santos Xavier <isoron@gmail.com>
+ *
+ * This file is part of Loop Habit Tracker.
+ *
+ * Loop Habit Tracker is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version.
+ *
+ * Loop Habit Tracker is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.isoron.uhabits.core.sync
+
+import kotlinx.coroutines.*
+import org.hamcrest.Matchers.*
+import org.isoron.uhabits.sync.*
+import org.junit.*
+import org.junit.Assert.*
+import java.io.*
+import java.util.*
+
+class EncryptionExtTest {
+
+    @Test
+    fun test_encode_decode() {
+        val original = ByteArray(5000)
+        Random().nextBytes(original)
+        val encoded = original.encodeBase64()
+        val decoded = encoded.decodeBase64()
+        assertThat(decoded, equalTo(original))
+    }
+
+    @Test
+    fun test_encrypt_decrypt_bytes() = runBlocking {
+        val original = ByteArray(5000)
+        Random().nextBytes(original)
+        val key = EncryptionKey.generate()
+        val encrypted = original.encrypt(key)
+        val decrypted = encrypted.decrypt(key)
+        assertThat(decrypted, equalTo(original))
+    }
+
+    @Test
+    fun test_encrypt_decrypt_file() = runBlocking {
+        val original = File.createTempFile("file", ".txt")
+        val writer = PrintWriter(original.outputStream())
+        writer.println("hello world")
+        writer.println("encryption test")
+        writer.close()
+        assertThat(original.length(), equalTo(28L))
+
+        val key = EncryptionKey.generate()
+        val encrypted = original.encryptToString(key)
+        assertThat(encrypted.length, greaterThan(10))
+
+        val decrypted = File.createTempFile("file", ".txt")
+        encrypted.decryptToFile(key, decrypted)
+        assertThat(decrypted.length(), equalTo(28L))
+        assertEquals("hello world\nencryption test\n", decrypted.readText())
+    }
+}