diff --git a/Resources/config.json b/Resources/config.json
index 5f23903..057eb42 100644
--- a/Resources/config.json
+++ b/Resources/config.json
@@ -1,4 +1,7 @@
 {
     "logPath": "\/var\/log\/caps.log",
-    "serveFiles": true
+    "serveFiles": true,
+    "writers" : [
+        "auth_key_1"
+    ]
 }
diff --git a/Sources/App/CapServer.swift b/Sources/App/CapServer.swift
index aa6a784..67df1c6 100644
--- a/Sources/App/CapServer.swift
+++ b/Sources/App/CapServer.swift
@@ -16,6 +16,8 @@ final class CapServer {
 
     private var saveImmediatelly = true
 
+    private var writers: Set<String>
+
     private var caps = [Int: Cap]() {
         didSet {
             guard saveImmediatelly else {
@@ -26,12 +28,13 @@ final class CapServer {
     }
 
     var nextClassifierVersion: Int {
-        caps.values.map { $0.classifierVersion }.max() ?? 1
+        caps.values.compactMap { $0.classifierVersion }.max() ?? 1
     }
     
-    init(in folder: URL) throws {
+    init(in folder: URL, writers: [String]) throws {
         self.imageFolder = folder.appendingPathComponent("images")
         self.dbFile = folder.appendingPathComponent("caps.json")
+        self.writers = Set(writers)
         
         var isDirectory: ObjCBool = false
         guard fm.fileExists(atPath: folder.path, isDirectory: &isDirectory),
@@ -65,6 +68,17 @@ final class CapServer {
     func file(of cap: Int, version: Int) -> URL {
         folder(of: cap).appendingPathComponent(String(format: "%04d-%02d.jpg", cap, version))
     }
+
+    // MARK: Authentication
+
+    func hasAuthorization(for key: String) -> Bool {
+        // Note: This is not a constant-time compare, so there may be an opportunity
+        // for timing attack here. Sets perform hashed lookups, so this may be less of an issue,
+        // and we're not doing anything critical in this application.
+        // Worst case, an unauthorized person with a lot of free time and energy to hack this system
+        // is able to change contents of the database, which are backed up in any case.
+        writers.contains(key)
+    }
     
     // MARK: Counts
 
diff --git a/Sources/App/Config.swift b/Sources/App/Config.swift
index e1740cd..b361f61 100644
--- a/Sources/App/Config.swift
+++ b/Sources/App/Config.swift
@@ -2,15 +2,20 @@ import Foundation
 
 struct Config: Codable {
 
+    /// The path to the log file
     let logPath: String
 
+    /// Serve files in the Public directory using Vapor
     let serveFiles: Bool
 
+    /// Authentication tokens for remotes allowed to write
+    let writers: [String]
+
     var logURL: URL {
         .init(fileURLWithPath: logPath)
     }
 
     static var `default`: Config {
-        .init(logPath: "/var/log/caps.log", serveFiles: true)
+        .init(logPath: "/var/log/caps.log", serveFiles: true, writers: [])
     }
 }
diff --git a/Sources/App/configure.swift b/Sources/App/configure.swift
index c37b4f0..b620b89 100755
--- a/Sources/App/configure.swift
+++ b/Sources/App/configure.swift
@@ -30,7 +30,8 @@ public func configure(_ app: Application) throws {
         app.middleware.use(middleware)
     }
 
-    server = try CapServer(in: URL(fileURLWithPath: publicDirectory))
+    server = try CapServer(in: URL(fileURLWithPath: publicDirectory),
+                           writers: config.writers)
     
     // Register routes to the router
     try routes(app)
diff --git a/Sources/App/routes.swift b/Sources/App/routes.swift
index 161df1f..c75d979 100755
--- a/Sources/App/routes.swift
+++ b/Sources/App/routes.swift
@@ -1,5 +1,12 @@
 import Vapor
 
+private func authorize(_ request: Request) throws {
+    let key = try request.query.get(String.self, at: "key")
+    guard server.hasAuthorization(for: key) else {
+        throw Abort(.forbidden)
+    }
+}
+
 /// Register your application's routes here.
 ///
 /// [Learn More →](https://docs.vapor.codes/3.0/getting-started/structure/#routesswift)
@@ -7,6 +14,7 @@ func routes(_ app: Application) throws {
     
     // Set the name of a cap
     app.postCatching("name", ":n") { request in
+        try authorize(request)
         guard let cap = request.parameters.get("n", as: Int.self) else {
             log("Invalid parameter for cap")
             throw Abort(.badRequest)
@@ -20,6 +28,7 @@ func routes(_ app: Application) throws {
     
     // Upload an image
     app.postCatching("images", ":n") { request -> Data in
+        try authorize(request)
         guard let cap = request.parameters.get("n", as: Int.self) else {
             log("Invalid parameter for cap")
             throw Abort(.badRequest)
@@ -35,6 +44,7 @@ func routes(_ app: Application) throws {
     
     // Set a different version as the main image
     app.getCatching("switch", ":n", ":v") { request in
+        try authorize(request)
         guard let cap = request.parameters.get("n", as: Int.self), cap >= 0 else {
             log("Invalid parameter for cap")
             throw Abort(.badRequest)