Base32 encoder fix (#19)

- Fixed Base32 encoder #6, added test
- Updated NuGet packages

Author: XFox111

SimpleOTP.Test/Helpers/Base32UnitTest.cs

@@ -6,6 +6,7 @@
 // ------------------------------------------------------------
 
 using System;
+using System.Text;
 
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using SimpleOTP.Helpers;
@@ -19,19 +20,33 @@ namespace SimpleOTP.Test.Helpers
 	public class Base32UnitTest
 	{
 		/// <summary>
-		/// Test overall work of the encoder.
+		/// Test encoder with byte array.
 		/// </summary>
-		[TestMethod("Overall Base32 encoder test")]
+		[TestMethod("Byte array Base32 encoder test")]
 		public void EncoderTest()
 		{
-			// byte[] bytes = new byte[new Random().Next(128, 161)];    // FIXME: See SimpleOTP.Helpers.Base32Encoder.Encode()
-			byte[] bytes = new byte[160];
+			byte[] bytes = new byte[new Random().Next(16, 20)];
 			new Random().NextBytes(bytes);
 			string str = Base32Encoder.Encode(bytes);
 
-			bytes = Base32Encoder.Decode(str);
-			string result = Base32Encoder.Encode(bytes);
-			Assert.AreEqual(str, result);
+			byte[] result = Base32Encoder.Decode(str);
+			Assert.AreEqual(bytes.Length, result.Length);
+			for (int i = 0; i < bytes.Length; i++)
+				Assert.AreEqual(bytes[i], result[i]);
+		}
+
+		/// <summary>
+		/// Test encoder with string content.
+		/// </summary>
+		[TestMethod("String Base32 encoder test")]
+		public void EncoderStringTest()
+		{
+			string testStr = "Hello, World!";
+			string encodedStr = Base32Encoder.Encode(Encoding.UTF8.GetBytes(testStr));
+
+			byte[] resultBytes = Base32Encoder.Decode(encodedStr);
+			string result = Encoding.UTF8.GetString(resultBytes);
+			Assert.AreEqual(testStr, result);
 		}
 	}
 }

SimpleOTP.Test/Models/OTPConfigurationUnitTest.cs

@@ -87,4 +87,4 @@ public async Task GetQrImage()
 				"yEEBMhxEQIMRFCTIQQEyHERAgxEUJMhBATIcRECDERQkyEEBMhxEQIMRFCTIQQEyHE/gcIt5Gg5RNZHAAAAABJRU5ErkJggg==", imageStr);
 		}
 	}
-}
+}

SimpleOTP.Test/SimpleOTP.Test.csproj

@@ -24,8 +24,8 @@
 
 	<ItemGroup>
 		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.10.0" />
-		<PackageReference Include="MSTest.TestAdapter" Version="2.2.4" />
-		<PackageReference Include="MSTest.TestFramework" Version="2.2.4" />
+		<PackageReference Include="MSTest.TestAdapter" Version="2.2.5" />
+		<PackageReference Include="MSTest.TestFramework" Version="2.2.5" />
 		<PackageReference Include="coverlet.collector" Version="3.0.3">
 			<PrivateAssets>all</PrivateAssets>
 			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>

SimpleOTP/Helpers/Base32Encoder.cs

@@ -5,7 +5,8 @@
 // Licensed under MIT license (https://opensource.org/licenses/MIT)
 // ------------------------------------------------------------
 
-using System.Collections.Generic;
+using System;
+using System.Linq;
 
 namespace SimpleOTP.Helpers
 {
@@ -14,6 +15,7 @@ namespace SimpleOTP.Helpers
 	/// </summary>
 	internal static class Base32Encoder
 	{
+		// Standard RFC 4648 Base32 alphabet
 		private const string AllowedCharacters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
 
 		/// <summary>
@@ -23,16 +25,20 @@ internal static class Base32Encoder
 		/// <returns>Base32 string.</returns>
 		internal static string Encode(byte[] data)
 		{
-			// FIXME: Encoder works correctly only with 160-bit keys
+			string binary = string.Empty;
+			foreach (byte b in data)
+				binary += Convert.ToString(b, 2).PadLeft(8, '0');   // Getting binary sequence to split into 5 digits
+
+			int numberOfBlocks = (binary.Length / 5) + Math.Clamp(binary.Length % 5, 0, 1);
+			string[] sequence = Enumerable.Range(0, numberOfBlocks)
+				.Select(i => binary.Substring(i * 5, Math.Min(5, binary.Length - (i * 5))).PadRight(5, '0'))
+				.ToArray();   // Splitting sequence on groups of 5
+
 			string output = string.Empty;
-			for (int bitIndex = 0; bitIndex < data.Length * 8; bitIndex += 5)
-			{
-				int dualbyte = data[bitIndex / 8] << 8;
-				if ((bitIndex / 8) + 1 < data.Length)
-					dualbyte |= data[(bitIndex / 8) + 1];
-				dualbyte = 0x1f & (dualbyte >> (16 - (bitIndex % 8) - 5));
-				output += AllowedCharacters[dualbyte];
-			}
+			foreach (string str in sequence)
+				output += AllowedCharacters[Convert.ToInt32(str, 2)];
+
+			output = output.PadRight(output.Length + (output.Length % 8), '=');
 
 			return output;
 		}
@@ -44,21 +50,14 @@ internal static string Encode(byte[] data)
 		/// <returns>Initial byte array.</returns>
 		internal static byte[] Decode(string base32str)
 		{
-			List<byte> output = new ();
-			char[] bytes = base32str.ToCharArray();
-			for (var bitIndex = 0; bitIndex < base32str.Length * 5; bitIndex += 8)
-			{
-				var dualbyte = AllowedCharacters.IndexOf(bytes[bitIndex / 5]) << 10;
-				if ((bitIndex / 5) + 1 < bytes.Length)
-					dualbyte |= AllowedCharacters.IndexOf(bytes[(bitIndex / 5) + 1]) << 5;
-				if ((bitIndex / 5) + 2 < bytes.Length)
-					dualbyte |= AllowedCharacters.IndexOf(bytes[(bitIndex / 5) + 2]);
+			base32str = base32str.Replace("=", string.Empty);   // Removing padding
 
-				dualbyte = 0xff & (dualbyte >> (15 - (bitIndex % 5) - 8));
-				output.Add((byte)dualbyte);
-			}
+			string[] quintets = base32str.Select(i => Convert.ToString(AllowedCharacters.IndexOf(i), 2).PadLeft(5, '0')).ToArray();     // Getting quintets
+			string binary = string.Join(null, quintets);
 
-			return output.ToArray();
+			byte[] output = Enumerable.Range(0, binary.Length / 8).Select(i => Convert.ToByte(binary.Substring(i * 8, 8), 2)).ToArray();
+
+			return output;
 		}
 	}
 }

SimpleOTP/Helpers/SecretGenerator.cs

@@ -20,7 +20,7 @@ public static class SecretGenerator
 		/// <param name="length">Length of the key in bits<br/>
 		/// It should belong to [128-160] bit span<br/>
 		/// Default is: 160 bits.</param>
-		/// <remarks>CURRENTLY THIS GENERATOR WORKS CORRECTLY ONLY WITH 160-BIT LENGTHS. Set <paramref name="length"/> at your own risk.</remarks>
+		/// <remarks>Number of bits will be rounded down to the nearest number which divides by 8.</remarks>
 		/// <returns>Base32 encoded alphanumeric string with length form 16 to 20 characters.</returns>
 		public static string GenerateSecret(int length = 160)
 		{

SimpleOTP/SimpleOTP.csproj

@@ -12,7 +12,7 @@
 	<PropertyGroup>
 		<PackageId>SimpleOTP</PackageId>
 		<AssemblyName>SimpleOTP</AssemblyName>
-		<Version>1.2.1</Version>
+		<Version>1.2.2</Version>
 		<Description>.NET library for TOTP/HOTP implementation on server (ASP.NET) or client (Xamarin) side</Description>
 		<Authors>Eugene Fox</Authors>
 		<Company>FoxDev Studio</Company>
@@ -22,8 +22,8 @@
 		<RepositoryUrl>https://github.com/XFox111/SimpleOTP</RepositoryUrl>
 		<NeutralLanguage>en-US</NeutralLanguage>
 		<PackageTags>otp;totp;dotnet;hotp;authenticator;2fa;mfa;security;oath</PackageTags>
-		<PackageReleaseNotes>- Fixed generated secret length
-- Fixed URI encoding issues in 'OTPConfiguration.GetUri()'</PackageReleaseNotes>
+		<PackageReleaseNotes>- Fixed Base32 encoder
+- Updated NuGet dependency packages</PackageReleaseNotes>
 	</PropertyGroup>
 
 	<PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">