diff --git a/android/uhabits-android/src/androidTest/java/org/isoron/uhabits/utils/EncryptionExtTest.kt b/android/uhabits-android/src/androidTest/java/org/isoron/uhabits/utils/EncryptionExtTest.kt
index 48f37d75f..5569ef1f7 100644
--- a/android/uhabits-android/src/androidTest/java/org/isoron/uhabits/utils/EncryptionExtTest.kt
+++ b/android/uhabits-android/src/androidTest/java/org/isoron/uhabits/utils/EncryptionExtTest.kt
@@ -18,11 +18,36 @@
  */
 package org.isoron.uhabits.utils
 
+import androidx.test.filters.*
+import org.hamcrest.Matchers.*
 import org.isoron.uhabits.*
 import org.junit.*
+import org.junit.Assert.*
 import java.io.*
+import java.util.*
 
+@MediumTest
 class EncryptionExtTest : BaseAndroidTest() {
+
+    @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() {
+        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() {
         val original = File.createTempFile("file", ".txt")
@@ -30,12 +55,15 @@ class EncryptionExtTest : BaseAndroidTest() {
         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())
     }
 }
diff --git a/android/uhabits-android/src/main/java/org/isoron/uhabits/utils/EncryptionExt.kt b/android/uhabits-android/src/main/java/org/isoron/uhabits/utils/EncryptionExt.kt
index e77267ce4..86f0cce44 100644
--- a/android/uhabits-android/src/main/java/org/isoron/uhabits/utils/EncryptionExt.kt
+++ b/android/uhabits-android/src/main/java/org/isoron/uhabits/utils/EncryptionExt.kt
@@ -38,17 +38,17 @@ import javax.crypto.spec.*
  */
 class EncryptionKey private constructor(
         val base64: String,
-        val secretKey: SecretKey,
+        val secretKey: SecretKey
 ) {
     companion object {
 
         fun fromBase64(base64: String): EncryptionKey {
-            val keySpec = SecretKeySpec(Base64.decode(base64, Base64.DEFAULT), "AES")
+            val keySpec = SecretKeySpec(base64.decodeBase64(), "AES")
             return EncryptionKey(base64, keySpec)
         }
 
         private fun fromSecretKey(spec: SecretKey): EncryptionKey {
-            val base64 = Base64.encodeToString(spec.encoded, Base64.DEFAULT).trim()
+            val base64 = spec.encoded.encodeBase64().trim()
             return EncryptionKey(base64, spec)
         }
 
@@ -99,7 +99,7 @@ fun ByteArray.decrypt(key: EncryptionKey): ByteArray {
  * gzip, decrypts it with the provided key, then writes the output to the specified file.
  */
 fun String.decryptToFile(key: EncryptionKey, output: File) {
-    val bytes = Base64.decode(this, Base64.DEFAULT).decrypt(key)
+    val bytes = this.decodeBase64().decrypt(key)
     ByteArrayInputStream(bytes).use { bytesInputStream ->
         GZIPInputStream(bytesInputStream).use { gzipInputStream ->
             FileOutputStream(output).use { fileOutputStream ->
@@ -120,10 +120,14 @@ fun File.encryptToString(key: EncryptionKey): String {
         FileInputStream(this).use { inputStream ->
             GZIPOutputStream(bytesOutputStream).use { gzipOutputStream ->
                 ByteStreams.copy(inputStream, gzipOutputStream)
+                gzipOutputStream.close()
                 val bytes = bytesOutputStream.toByteArray()
-                return Base64.encodeToString(bytes.encrypt(key), Base64.DEFAULT)
+                return bytes.encrypt(key).encodeBase64()
             }
         }
     }
 }
 
+fun ByteArray.encodeBase64(): String = Base64.encodeToString(this, Base64.DEFAULT)
+fun String.decodeBase64(): ByteArray = Base64.decode(this, Base64.DEFAULT)
+