add EncryptedEventStream

Author: wenxi-zeng

core/src/main/java/com/segment/analytics/kotlin/core/utilities/EventStream.kt

@@ -85,10 +85,10 @@ interface EventStream {
     fun readAsStream(source: String): InputStream?
 }
 
-class InMemoryEventStream: EventStream {
-    private val directory = ConcurrentHashMap<String, InMemoryFile>()
+open class InMemoryEventStream: EventStream {
+    protected val directory = ConcurrentHashMap<String, InMemoryFile>()
 
-    private var currFile: InMemoryFile? = null
+    protected open var currFile: InMemoryFile? = null
 
     override val length: Long
         get() = (currFile?.length ?: 0).toLong()
@@ -154,7 +154,7 @@ class InMemoryEventStream: EventStream {
     }
 }
 
-class FileEventStream(
+open class FileEventStream(
     internal val directory: File
 ): EventStream {
 
@@ -163,9 +163,9 @@ class FileEventStream(
         registerShutdownHook()
     }
 
-    private var fs: FileOutputStream? = null
+    protected open var fs: FileOutputStream? = null
 
-    private var currFile: File? = null
+    protected open var currFile: File? = null
 
     override val length: Long
         get() = currFile?.length() ?: 0

samples/kotlin-android-app/src/main/java/com/segment/analytics/next/EncryptedEventStream.kt

@@ -0,0 +1,97 @@
+package com.segment.analytics.next
+
+import com.segment.analytics.kotlin.core.Analytics
+import com.segment.analytics.kotlin.core.Storage
+import com.segment.analytics.kotlin.core.StorageProvider
+import com.segment.analytics.kotlin.core.utilities.FileEventStream
+import com.segment.analytics.kotlin.core.utilities.PropertiesFile
+import com.segment.analytics.kotlin.core.utilities.StorageImpl
+import java.io.File
+import java.io.FileOutputStream
+import java.io.InputStream
+import java.security.Key
+import javax.crypto.Cipher
+import javax.crypto.CipherInputStream
+import javax.crypto.CipherOutputStream
+import javax.crypto.KeyGenerator
+
+class EncryptedEventStream(
+    directory: File,
+    private val key: Key
+) : FileEventStream(directory) {
+
+    private var cipherOutputStream: CipherOutputStream? = null
+
+    private val encryptedCipher = EncryptionUtil.getCipher(key, Cipher.ENCRYPT_MODE)
+
+    override var fs: FileOutputStream?
+        get() = super.fs
+        set(value) {
+            if (value == null) {
+                cipherOutputStream = null
+            }
+            else {
+                cipherOutputStream = CipherOutputStream(value, encryptedCipher)
+            }
+        }
+
+    override fun write(content: String) {
+        cipherOutputStream?.run {
+            write(content.toByteArray())
+            flush()
+        }
+    }
+
+    override fun close() {
+        cipherOutputStream?.close()
+        super.close()
+    }
+
+    override fun readAsStream(source: String): InputStream? {
+        val stream = super.readAsStream(source)
+        return if (stream == null) {
+            null
+        } else {
+            val cipher = EncryptionUtil.getCipher(key, Cipher.DECRYPT_MODE)
+            CipherInputStream(super.readAsStream(source), cipher)
+        }
+    }
+}
+
+object EncryptedStorageProvider : StorageProvider {
+
+    override fun createStorage(vararg params: Any): Storage {
+        if (params.isEmpty() || params[0] !is Analytics || params[1] !is Key) {
+            throw IllegalArgumentException("Invalid parameters for ConcreteStorageProvider. ConcreteStorageProvider requires at least 1 parameter and the first argument has to be an instance of Analytics")
+        }
+
+        val analytics = params[0] as Analytics
+        val key = params[1] as Key
+        val config = analytics.configuration
+
+        val directory = File("/tmp/analytics-kotlin/${config.writeKey}")
+        val eventDirectory = File(directory, "events")
+        val fileIndexKey = "segment.events.file.index.${config.writeKey}"
+        val userPrefs = File(directory, "analytics-kotlin-${config.writeKey}.properties")
+
+        val propertiesFile = PropertiesFile(userPrefs)
+        val eventStream = EncryptedEventStream(eventDirectory, key)
+        return StorageImpl(propertiesFile, eventStream, analytics.store, config.writeKey, fileIndexKey, analytics.fileIODispatcher)
+    }
+}
+
+object EncryptionUtil {
+    private const val ALGORITHM = "AES"
+
+    fun generateKey(): Key {
+        val keyGen = KeyGenerator.getInstance(ALGORITHM)
+        keyGen.init(128) // AES 128-bit key
+        return keyGen.generateKey()
+    }
+
+    fun getCipher(key: Key, mode: Int): Cipher {
+        val cipher = Cipher.getInstance(ALGORITHM)
+        cipher.init(mode, key)
+        return cipher
+    }
+}