Missing files + start working on offline patcher

SafeExamBrowser.Proctoring/ScreenProctoring/Encryptor.cs

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+/*
+ * Copyright (c) 2025 ETH Zürich, IT Services
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+using System;
+using System.Linq;
+using System.Text;
+using Org.BouncyCastle.Crypto.Engines;
+using Org.BouncyCastle.Crypto.Modes;
+using Org.BouncyCastle.Crypto.Parameters;
+using SafeExamBrowser.Settings.Proctoring;
+
+namespace SafeExamBrowser.Proctoring.ScreenProctoring
+{
+	internal class Encryptor
+	{
+		private const int IV_BYTES = 16;
+		private const int MAC_BITS = 128;
+
+		private readonly Lazy<byte[]> encryptionSecret;
+
+		internal Encryptor(ScreenProctoringSettings settings)
+		{
+			encryptionSecret = new Lazy<byte[]>(() => Encoding.UTF8.GetBytes(settings.EncryptionSecret));
+		}
+
+		internal byte[] Decrypt(byte[] data)
+		{
+			var (iv, encrypted) = Split(data);
+			var cipher = new GcmBlockCipher(new AesEngine());
+			var key = new KeyParameter(encryptionSecret.Value);
+			var parameters = new AeadParameters(key, MAC_BITS, iv);
+
+			cipher.Init(false, parameters);
+
+			var outputSize = cipher.GetOutputSize(encrypted.Length);
+			var decrypted = new byte[outputSize];
+			var offset = cipher.ProcessBytes(encrypted, 0, encrypted.Length, decrypted, 0);
+
+			cipher.DoFinal(decrypted, offset);
+
+			return decrypted;
+		}
+
+		internal byte[] Encrypt(byte[] data)
+		{
+			var cipher = new GcmBlockCipher(new AesEngine());
+			var iv = GenerateInitializationVector();
+			var key = new KeyParameter(encryptionSecret.Value);
+			var parameters = new AeadParameters(key, MAC_BITS, iv);
+
+			cipher.Init(true, parameters);
+
+			var outputSize = cipher.GetOutputSize(data.Length);
+			var encrypted = new byte[outputSize];
+			var offset = cipher.ProcessBytes(data, 0, data.Length, encrypted, 0);
+
+			cipher.DoFinal(encrypted, offset);
+
+			return Merge(iv, encrypted);
+		}
+
+		private byte[] GenerateInitializationVector()
+		{
+			var vector = new byte[IV_BYTES];
+			var random = new Random();
+
+			random.NextBytes(vector);
+
+			return vector;
+		}
+
+		private byte[] Merge(byte[] iv, byte[] encrypted)
+		{
+			return iv.Concat(encrypted).ToArray();
+		}
+
+		private (byte[] iv, byte[] encrypted) Split(byte[] data)
+		{
+			var iv = data.Take(IV_BYTES).ToArray();
+			var encrypted = data.Skip(IV_BYTES).ToArray();
+
+			return (iv, encrypted);
+		}
+	}
+}

SafeExamBrowser.Proctoring/ScreenProctoring/Service/Sanitizer.cs

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+/*
+ * Copyright (c) 2025 ETH Zürich, IT Services
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+using System;
+using System.Reflection;
+
+namespace SafeExamBrowser.Proctoring.ScreenProctoring.Service
+{
+	internal class Sanitizer
+	{
+		internal Uri Sanitize(string serviceUrl)
+		{
+			return new Uri(serviceUrl.EndsWith("/") ? serviceUrl : $"{serviceUrl}/");
+		}
+
+		internal void Sanitize(Api api)
+		{
+			foreach (var property in api.GetType().GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic))
+			{
+				var value = property.GetValue(api) as string;
+				var sanitized = value.TrimStart('/');
+
+				property.SetValue(api, sanitized);
+			}
+		}
+	}
+}

SafeExamBrowser.Proctoring/app.config

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+<?xml version="1.0" encoding="utf-8"?>
+<configuration>
+  <runtime>
+    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
+      <dependentAssembly>
+        <assemblyIdentity name="KGySoft.CoreLibraries" publicKeyToken="b45eba277439ddfe" culture="neutral" />
+        <bindingRedirect oldVersion="0.0.0.0-8.3.0.0" newVersion="8.3.0.0" />
+      </dependentAssembly>
+      <dependentAssembly>
+        <assemblyIdentity name="KGySoft.Drawing.Core" publicKeyToken="b45eba277439ddfe" culture="neutral" />
+        <bindingRedirect oldVersion="0.0.0.0-8.2.0.0" newVersion="8.2.0.0" />
+      </dependentAssembly>
+    </assemblyBinding>
+  </runtime>
+</configuration>