diff --git a/app/app/build.gradle.kts b/app/app/build.gradle.kts
index b8ed094..66015a4 100644
--- a/app/app/build.gradle.kts
+++ b/app/app/build.gradle.kts
@@ -1,8 +1,30 @@
+import com.google.protobuf.gradle.*
+
 plugins {
     alias(libs.plugins.android.application)
     alias(libs.plugins.jetbrains.kotlin.android)
     alias(libs.plugins.compose.compiler)
     alias(libs.plugins.serialization)
+    alias(libs.plugins.protobuf)
+}
+
+protobuf {
+    protoc {
+        artifact = "com.google.protobuf:protoc:3.24.1"
+    }
+
+    generateProtoTasks {
+        all().forEach { task ->
+            task.builtins {
+                id("java") {
+                    option("lite")
+                }
+                id("kotlin") {
+                    option("lite")
+                }
+            }
+        }
+    }
 }
 
 android {
@@ -76,6 +98,8 @@ dependencies {
     implementation(platform(libs.androidx.compose.bom))
     implementation(libs.okhttp)
     implementation(libs.okhttp.logging.interceptor)
+    implementation(libs.protobuf.javalite)
+    implementation(libs.protobuf.kotlinlite)
 
     testImplementation(libs.junit)
     androidTestImplementation(libs.androidx.junit)
diff --git a/app/app/src/main/java/ing/bikeshedengineer/debtpirate/Store.kt b/app/app/src/main/java/ing/bikeshedengineer/debtpirate/Store.kt
new file mode 100644
index 0000000..a0157e5
--- /dev/null
+++ b/app/app/src/main/java/ing/bikeshedengineer/debtpirate/Store.kt
@@ -0,0 +1,30 @@
+package ing.bikeshedengineer.debtpirate
+
+import android.content.Context
+import androidx.datastore.core.CorruptionException
+import androidx.datastore.core.DataStore
+import androidx.datastore.core.Serializer
+import androidx.datastore.dataStore
+import com.google.protobuf.InvalidProtocolBufferException
+import java.io.InputStream
+import java.io.OutputStream
+
+object StoreSerializer : Serializer<Store> {
+    override val defaultValue: Store
+        get() = Store.getDefaultInstance()
+
+    override suspend fun readFrom(input: InputStream): Store {
+        try {
+            return Store.parseFrom(input)
+        } catch (exception: InvalidProtocolBufferException) {
+            throw CorruptionException("Cannot read proto file.", exception)
+        }
+    }
+
+    override suspend fun writeTo(t: Store, output: OutputStream) = t.writeTo(output)
+}
+
+val Context.dataStore: DataStore<Store> by dataStore(
+    fileName = "store.proto",
+    serializer = StoreSerializer
+)
\ No newline at end of file
diff --git a/app/app/src/main/proto/store.proto b/app/app/src/main/proto/store.proto
new file mode 100644
index 0000000..7a4eafb
--- /dev/null
+++ b/app/app/src/main/proto/store.proto
@@ -0,0 +1,15 @@
+syntax = "proto3";
+
+option java_package = "ing.bikeshedengineer.debtpirate";
+option java_multiple_files = true;
+
+message Token {
+    string token = 1;
+    int64 expires_at = 2;
+}
+
+message Store {
+    int32 user_id = 1;
+    Token auth_token = 2;
+    Token session_token = 3;
+}
\ No newline at end of file
diff --git a/app/build.gradle.kts b/app/build.gradle.kts
index 143b7d2..a5cb1bf 100644
--- a/app/build.gradle.kts
+++ b/app/build.gradle.kts
@@ -4,4 +4,5 @@ plugins {
     alias(libs.plugins.jetbrains.kotlin.android) apply false
     alias(libs.plugins.compose.compiler) apply false
     alias(libs.plugins.serialization) apply false
+    alias(libs.plugins.protobuf) apply false
 }
diff --git a/app/gradle/libs.versions.toml b/app/gradle/libs.versions.toml
index 1afa73c..47832a0 100644
--- a/app/gradle/libs.versions.toml
+++ b/app/gradle/libs.versions.toml
@@ -18,8 +18,10 @@ lifecycleViewmodelCompose = "2.8.6"
 material = "1.12.0"
 material3 = "1.3.0"
 navigation = "2.8.2"
-retrofit = "2.9.0"
+protobuf = "0.9.4"
+protoLite = "3.21.11"
 okhttp = "4.10.0"
+retrofit = "2.9.0"
 
 [libraries]
 androidx-activity-compose = { group = "androidx.activity", name = "activity-compose", version.ref = "activityCompose" }
@@ -50,9 +52,12 @@ retrofit = { group = "com.squareup.retrofit2", name = "retrofit", version.ref =
 retrofit-gson = { group = "com.squareup.retrofit2", name = "converter-gson", version.ref = "retrofit" }
 okhttp = { group = "com.squareup.okhttp3", name = "okhttp", version.ref = "okhttp" }
 okhttp-logging-interceptor = { group = "com.squareup.okhttp3", name = "logging-interceptor", version.ref = "okhttp" }
+protobuf-javalite = { group = "com.google.protobuf", name = "protobuf-javalite", version.ref = "protoLite" }
+protobuf-kotlinlite = { group = "com.google.protobuf", name = "protobuf-kotlin-lite", version.ref = "protoLite" }
 
 [plugins]
 android-application = { id = "com.android.application", version.ref = "agp" }
 jetbrains-kotlin-android = { id = "org.jetbrains.kotlin.android", version.ref = "kotlin" }
 compose-compiler = { id = "org.jetbrains.kotlin.plugin.compose", version.ref = "kotlin" }
 serialization = { id = "org.jetbrains.kotlin.plugin.serialization", version.ref = "kotlin" }
+protobuf = { id = "com.google.protobuf", version.ref = "protobuf" }
\ No newline at end of file