Version 3.0.381

LockIt.BusinessLogic/Services/BluetoothLock/Crypto/AuthCryptoHelper.cs

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+using Serilog;
+using ShareeBike.Model.Device;
+
+namespace ShareeBike.Services.BluetoothLock.Crypto
+{
+	public class AuthCryptoHelper
+	{
+		private ICipher Cipher { get; }
+
+		/// <summary> Encrypted seed (random number) created inside ILOCKIT and passd to app.</summary>
+		private byte[] SeedLockEncrypted { get; }
+
+		/// <summary> Contstructs a auth crypto helper object.</summary>
+		/// <param name="seedLockEncrypted">Encrypted seed to deocode using <see cref="KeyCopri"/>.</param>
+		/// <param name="keyCopri">Key used to to decrypt <see cref="SeedLockEncrypted"/>.</param>
+		public AuthCryptoHelper(
+			 byte[] seedLockEncrypted,
+			 byte[] keyCopri,
+			 ICipher cipher)
+		{
+			KeyCopri = keyCopri;
+			SeedLockEncrypted = seedLockEncrypted;
+			Cipher = cipher ?? new Cipher();
+		}
+
+
+		/// <summary> Public for testing purposes only.</summary>
+		public byte[] GetSeedLock()
+		{
+			byte[] seedLockDecrypted;
+			var seedLockEncrypted = SeedLockEncrypted;
+			var keyCopri = KeyCopri;
+			try
+			{
+				seedLockDecrypted = Cipher.Decrypt(
+						keyCopri,
+						seedLockEncrypted);
+			}
+			catch (System.Exception exception)
+			{
+				Log.ForContext<AuthCryptoHelper>().Error("Decrypting seed from lock failed. {Exception}", exception);
+				throw;
+			}
+
+			Log.ForContext<AuthCryptoHelper>().Verbose($"Lock random number decrypted from {string.Join(",", seedLockEncrypted)} to {string.Join(",", seedLockDecrypted)} using {string.Join(", ", keyCopri)}.");
+			return seedLockDecrypted;
+		}
+
+		public byte[] GetAccessKeyEncrypted()
+		{
+
+			var accessKey = GetSeedLock();
+
+			if (accessKey == null || accessKey.Length <= 0)
+			{
+				Log.ForContext<AuthCryptoHelper>().Error("Creating access key failed, Key must not be null or empty.");
+				throw new System.Exception();
+			}
+
+			accessKey[accessKey.Length - 1] += 1;
+
+			var keyCopri = KeyCopri;
+			byte[] acccessKeyEncrypted;
+			try
+			{
+				acccessKeyEncrypted = Cipher.Encrypt(
+					keyCopri,
+					accessKey);
+			}
+			catch (System.Exception exception)
+			{
+				Log.ForContext<AuthCryptoHelper>().Error("Encrypting access key failed. {Exception}", exception);
+				throw;
+			}
+
+			Log.ForContext<AuthCryptoHelper>().Verbose($"Access key encrypted from {string.Join(",", accessKey)} to {string.Join(",", acccessKeyEncrypted)} using {string.Join(", ", keyCopri)}.");
+			return acccessKeyEncrypted;
+		}
+
+		public byte[] KeyCopri { get; }
+	}
+}

LockIt.BusinessLogic/Services/BluetoothLock/Crypto/Cipher.cs

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+using System;
+using System.IO;
+using System.Security.Cryptography;
+using ShareeBike.Model.Device;
+
+namespace ShareeBike.Services.BluetoothLock.Crypto
+{
+	public class Cipher : ICipher
+	{
+		/// <summary> Decrypt data. </summary>
+		/// <remarks>
+		/// Further info see:
+		/// https://docs.microsoft.com/en-us/dotnet/api/system.security.cryptography.aes?view=netcore-3.1 for further info
+		//  https://docs.microsoft.com/en-us/dotnet/standard/security/cryptographic-services
+		//  https://stackoverflow.com/questions/24903575/how-to-return-byte-when-decrypt-using-cryptostream-descryptoserviceprovider/24903689
+
+		/// </remarks>
+		/// <param name="key">Key to decrypt data with.</param>
+		/// <param name="encrypted">Encrpyted data to decrypt.</param>
+		/// <returns>Decrypted data.</returns>
+		public byte[] Decrypt(byte[] key, byte[] encrypted)
+		{
+			// Check arguments.
+			if (encrypted == null || encrypted.Length <= 0)
+				throw new ArgumentNullException(nameof(encrypted));
+
+			if (key == null || key.Length <= 0)
+				throw new ArgumentNullException(nameof(key));
+
+			using (Aes aesAlg = Aes.Create())
+			{
+				aesAlg.KeySize = 192;
+				aesAlg.Mode = CipherMode.ECB;
+				aesAlg.Padding = PaddingMode.None;
+				aesAlg.Key = key;
+
+				// Create a decryptor to perform the stream transform.
+				ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);
+
+				// Create the streams used for decryption.
+				using (var msDecrypt = new MemoryStream())
+				{
+					using (var csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Write))
+					{
+						csDecrypt.Write(encrypted, 0, encrypted.Length);
+						csDecrypt.FlushFinalBlock();
+						return msDecrypt.ToArray();
+					}
+				}
+			}
+		}
+
+		public byte[] Encrypt(byte[] key, byte[] clear)
+		{
+			// Check arguments.
+			if (clear == null || clear.Length <= 0)
+				throw new ArgumentNullException("plainText");
+
+			if (key == null || key.Length <= 0)
+				throw new ArgumentNullException("Key");
+
+			// Create an AesCryptoServiceProvider object
+			// with the specified key and IV.
+			using (AesCryptoServiceProvider aesAlg = new AesCryptoServiceProvider())
+			{
+				aesAlg.KeySize = 192;
+				aesAlg.Mode = CipherMode.ECB;
+				aesAlg.Padding = PaddingMode.None;
+				aesAlg.Key = key;
+
+				// Create an encryptor to perform the stream transform.
+				ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);
+
+				// Create the streams used for encryption.
+				using (var msEncrypt = new MemoryStream())
+				{
+					using (var csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
+					{
+						csEncrypt.Write(clear, 0, clear.Length);
+						csEncrypt.FlushFinalBlock();
+						return msEncrypt.ToArray();
+					}
+				}
+			}
+
+		}
+	}
+}