Encrypted Client card data block added. Android public and private keeys separated into different files.

QRBee.Core/Data/ClientCardData.cs

@@ -2,49 +2,20 @@
 {
     public class ClientCardData
     {
-
+        public string TransactionId      { get; set; }
-        public string CardNumber
+        public string CardNumber         { get; set; }
-        {
+        public string ExpirationDateMMYY { get; set; }
-            get;
+        public string ValidFrom          { get; set; }
-            set;
+        public string CardHolderName     { get; set; }
-        }
+        public string CVC                { get; set; }
-
+        public int? IssueNo              { get; set; }
-        public string ExpirationDateMMYY
-        {
-            get;
-            set;
-        }
-
-        public string ValidFrom
-        {
-            get;
-            set;
-        }
-
-        public string CardHolderName
-        {
-            get;
-            set;
-        }
-
-        public string CVC
-        {
-            get;
-            set;
-        }
-
-        public int? IssueNo
-        {
-            get;
-            set;
-        }
 
         /// <summary>
         /// Convert ClientCardData to string to be used as a source for encryption.
         /// WARNING: this should always be encrypted and never transmitted in clear text form.
         /// </summary>
         /// <returns>Converted string</returns>
-        public string AsString() => $"{CardNumber}|{ExpirationDateMMYY}|{ValidFrom}|{CardHolderName}|{CVC}|{IssueNo}";
+        public string AsString() => $"{TransactionId}|{CardNumber}|{ExpirationDateMMYY}|{ValidFrom}|{CardHolderName}|{CVC}|{IssueNo}";
 
     }
 }

QRBee.Core/Data/RegistrationResponse.cs

@@ -12,7 +12,13 @@ namespace QRBee.Core.Data
             set;
         }
 
-        public string Certificate
+        public string ClientCertificate
+        {
+            get;
+            set;
+        }
+
+        public string APIServerCertificate
         {
             get;
             set;

QRBee.Core/Security/IPrivateKeyHandler.cs

@@ -1,4 +1,5 @@
-using System.Security.Cryptography.X509Certificates;
+using System.Security.Cryptography;
+using System.Security.Cryptography.X509Certificates;
 
 namespace QRBee.Core.Security
 {
@@ -38,6 +39,12 @@ namespace QRBee.Core.Security
         /// self-signed until CA issues a proper certificate
         /// </summary>
         /// <returns></returns>
-        X509Certificate2 LoadPrivateKey();
+        RSA LoadPrivateKey();
+
+        /// <summary>
+        /// Get public key certificate
+        /// </summary>
+        /// <returns>Public key certificate</returns>
+        X509Certificate2 GetCertificate();
     }
 }

QRBee.Core/Security/ISecurityService.cs

@@ -47,6 +47,11 @@ namespace QRBee.Core.Security
 
         // -------------------------- certificate services --------------------------
 
+        /// <summary>
+        /// API Server certificate
+        /// </summary>
+        X509Certificate2 APIServerCertificate { get; set; }
+
         /// <summary>
         /// Convert binary block to X509Certificate2.
         /// <see cref="X509Certificate2.CreateFromPem"/>

QRBee.Core/Security/SecurityServiceBase.cs

@@ -39,12 +39,13 @@ namespace QRBee.Core.Security
         /// <inheritdoc/>
         public byte[] Decrypt(byte[] data)
         {
-            using var myCert = LoadPrivateKey();
+            using var rsa = LoadPrivateKey();
-            using var rsa = myCert.GetRSAPrivateKey();
             var res = rsa?.Decrypt(data, RSAEncryptionPadding.Pkcs1) ?? throw new CryptographicException("No private key found");
             return res;
         }
 
+        public abstract X509Certificate2 APIServerCertificate { get; set; }
+
         /// <inheritdoc/>
         public byte [] Encrypt(byte[] data, X509Certificate2 destCert)
         {
@@ -63,8 +64,7 @@ namespace QRBee.Core.Security
         /// <inheritdoc/>
         public byte[] Sign(byte[] data)
         {
-            using var myCert = LoadPrivateKey();
+            using var rsa = LoadPrivateKey();
-            using var rsa = myCert.GetRSAPrivateKey();
             var res = rsa?.SignData(data, 0, data.Length, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1) ?? throw new CryptographicException("No private key found");
             return res;
         }
@@ -86,16 +86,12 @@ namespace QRBee.Core.Security
             return serNo;
         }
 
-        private X509Certificate2 LoadPrivateKey()
+        private RSA LoadPrivateKey()
         {
             if (!PrivateKeyHandler.Exists())
                 PrivateKeyHandler.GeneratePrivateKey(); //TODO: subject name
 
             var pk = PrivateKeyHandler.LoadPrivateKey();
-            if (!IsValid(pk) )
-            {
-                throw new CryptographicException("CA private key is not valid");
-            }
 
             return pk;
         }

QRBee/QRBee.Android/Services/AndroidPrivateKeyHandler.cs

@@ -81,7 +81,7 @@ namespace QRBee.Droid.Services
         /// <inheritdoc/>
         public ReadableCertificateRequest CreateCertificateRequest(string subjectName)
         {
-            using var rsa = LoadRsaPrivateKey();
+            using var rsa = LoadPrivateKey();
 
             var request = new ReadableCertificateRequest
             {
@@ -96,85 +96,68 @@ namespace QRBee.Droid.Services
             return request;
         }
 
-        /// <summary>
+        ///// <summary>
-        /// Generate EXPORTABLE certificate
+        ///// Generate EXPORTABLE certificate
-        /// </summary>
+        ///// </summary>
-        /// <param name="subjectName"></param>
+        ///// <param name="subjectName"></param>
-        /// <returns></returns>
+        ///// <returns></returns>
-        private X509Certificate2 CreateSelfSignedClientCertificate(string subjectName)
+        //private X509Certificate2 CreateSelfSignedClientCertificate(string subjectName)
+        //{
+        //    // https://stackoverflow.com/questions/42786986/how-to-create-a-valid-self-signed-x509certificate2-programmatically-not-loadin
+
+        //    var distinguishedName = new X500DistinguishedName($"CN={subjectName}");
+
+        //    using var rsa = RSA.Create(RSABits);
+        //    var request = CreateRequest(distinguishedName, rsa);
+
+        //    var certificate = request.CreateSelfSigned(
+        //        new DateTimeOffset(DateTime.UtcNow.AddDays(-1)),
+        //        new DateTimeOffset(DateTime.UtcNow.AddDays(CertificateValidityDays))
+        //        );
+
+        //    return certificate;
+        //}
+
+        ///// <summary>
+        ///// Generate CA certificate request (i.e. with KeyCertSign usage extension)
+        ///// </summary>
+        ///// <param name="distinguishedName"></param>
+        ///// <param name="rsa"></param>
+        ///// <returns></returns>
+        //private static CertificateRequest CreateRequest(X500DistinguishedName distinguishedName, RSA rsa)
+        //{
+        //    //TODO not supported on Android
+        //    var request = new CertificateRequest(
+        //        distinguishedName,
+        //        rsa,
+        //        HashAlgorithmName.SHA256,
+        //        RSASignaturePadding.Pkcs1
+        //        );
+
+        //    request.CertificateExtensions.Add(
+        //        new X509KeyUsageExtension(
+        //              X509KeyUsageFlags.DataEncipherment
+        //            | X509KeyUsageFlags.KeyEncipherment
+        //            | X509KeyUsageFlags.DigitalSignature,
+        //    false));
+
+        //    return request;
+        //}
+
+
+        public X509Certificate2 GetCertificate()
         {
-            // https://stackoverflow.com/questions/42786986/how-to-create-a-valid-self-signed-x509certificate2-programmatically-not-loadin
+            
-
+            var cert = new X509Certificate2(PrivateKeyFileName);
-            var distinguishedName = new X500DistinguishedName($"CN={subjectName}");
+            return cert;
-
-            using var rsa = RSA.Create(RSABits);
-            var request = CreateRequest(distinguishedName, rsa);
-
-            var certificate = request.CreateSelfSigned(
-                new DateTimeOffset(DateTime.UtcNow.AddDays(-1)),
-                new DateTimeOffset(DateTime.UtcNow.AddDays(CertificateValidityDays))
-                );
-
-            return certificate;
-        }
-
-        /// <summary>
-        /// Generate CA certificate request (i.e. with KeyCertSign usage extension)
-        /// </summary>
-        /// <param name="distinguishedName"></param>
-        /// <param name="rsa"></param>
-        /// <returns></returns>
-        private static CertificateRequest CreateRequest(X500DistinguishedName distinguishedName, RSA rsa)
-        {
-            //TODO not supported on Android
-            var request = new CertificateRequest(
-                distinguishedName,
-                rsa,
-                HashAlgorithmName.SHA256,
-                RSASignaturePadding.Pkcs1
-                );
-
-            request.CertificateExtensions.Add(
-                new X509KeyUsageExtension(
-                      X509KeyUsageFlags.DataEncipherment
-                    | X509KeyUsageFlags.KeyEncipherment
-                    | X509KeyUsageFlags.DigitalSignature,
-            false));
-
-            return request;
-        }
-
-        /// <inheritdoc/>
-        public X509Certificate2 LoadPrivateKey()
-        {
-            if (_certificate != null)
-                return _certificate;
-
-            // double locking 
-            lock ( _syncObject )
-            {
-                if (_certificate != null)
-                    return _certificate;
-
-                if (!Exists())
-                    throw new CryptographicException("PrivateKey does not exist");
-
-                _certificate = new X509Certificate2(PrivateKeyFileName, VeryBadNeverUsePrivateKeyPassword);
-                return _certificate;
-            }
         }
 
         /// <inheritdoc/>
         public void AttachCertificate(X509Certificate2 cert)
         {
-            // heavily modified version of:
+            var bytes = cert.Export(X509ContentType.Cert);
-            // https://stackoverflow.com/questions/18462064/associate-a-private-key-with-the-x509certificate2-class-in-net
-            using var rsa = LoadRsaPrivateKey();
 
-            var newPk = cert.CopyWithPrivateKey(rsa);
+            File.WriteAllBytes(PrivateKeyFileName, bytes);
-
-            var pkcs12data = newPk.Export(X509ContentType.Pfx, VeryBadNeverUsePrivateKeyPassword);
-            File.WriteAllBytes(PrivateKeyFileName, pkcs12data);
 
             lock ( _syncObject )
             {
@@ -184,7 +167,7 @@ namespace QRBee.Droid.Services
             }
         }
 
-        private RSA LoadRsaPrivateKey()
+        public RSA LoadPrivateKey()
         {
             var bytes = File.ReadAllBytes(PrivateRsaKeyFileName);
             var s = CryptoHelper.DecryptStringAES(bytes, VeryBadNeverUsePrivateKeyPassword);

QRBee/QRBee.Android/Services/AndroidSecurityService.cs

@@ -1,12 +1,15 @@
 using System;
 using System.Security.Cryptography.X509Certificates;
 using System.Text;
+using System.IO;
 using QRBee.Core.Security;
 
 namespace QRBee.Droid.Services
 {
     internal class AndroidSecurityService : SecurityServiceBase
     {
+        private X509Certificate2 _apiServerCertificate;
+        private string ApiServerCertificateFileName => $"{Environment.GetFolderPath(System.Environment.SpecialFolder.LocalApplicationData)}/ApiServerCertificate.bin";
 
         public AndroidSecurityService(IPrivateKeyHandler privateKeyHandler)
         : base(privateKeyHandler)
@@ -51,6 +54,29 @@ namespace QRBee.Droid.Services
 
             return builder.ToString();
         }
+
+        public override X509Certificate2 APIServerCertificate
+        {
+            get
+            {
+                if (_apiServerCertificate != null)
+                {
+                    return _apiServerCertificate;
+                }
+
+                if (!File.Exists(ApiServerCertificateFileName))
+                    throw new ApplicationException($"File not found: {ApiServerCertificateFileName}");
+                var bytes = File.ReadAllBytes(ApiServerCertificateFileName);
+                _apiServerCertificate = new X509Certificate2(bytes);
+                return _apiServerCertificate;
+            }
+            set
+            {
+                _apiServerCertificate = value;
+                var bytes = _apiServerCertificate.Export(X509ContentType.Cert);
+                File.WriteAllBytes(ApiServerCertificateFileName,bytes);
+            }
+        }
     }
 
 }

QRBee/QRBee/Services/ILocalSettings.cs

@@ -7,7 +7,7 @@ namespace QRBee.Services
 {
     public class Settings
     {
-        //TODO add ClientId
+        
         public string ClientId       { get; set; }
         public string PIN            { get; set; }
         public bool IsRegistered => !string.IsNullOrWhiteSpace(ClientId); 
@@ -20,7 +20,7 @@ namespace QRBee.Services
         public string ExpirationDate { get; set; }
         public string CardHolderName { get; set; }
         public string CVC            { get; set; }
-        public string IssueNo        { get; set; }
+        public int? IssueNo        { get; set; }
         public string Password       { get; set; }
     }
 

QRBee/QRBee/ViewModels/ClientPageViewModel.cs

@@ -12,6 +12,7 @@ namespace QRBee.ViewModels
     {
         private readonly IQRScanner _scanner;
         private readonly ISecurityService _securityService;
+        private readonly ILocalSettings _localSettings;
         public bool _isAcceptDenyButtonVisible;
         public bool _isQrVisible;
         public bool _isScanButtonVisible;
@@ -21,10 +22,11 @@ namespace QRBee.ViewModels
         private string _qrCode;
         private MerchantToClientRequest _merchantToClientRequest;
 
-        public ClientPageViewModel(IQRScanner scanner, ISecurityService securityService)
+        public ClientPageViewModel(IQRScanner scanner, ISecurityService securityService, ILocalSettings localSettings)
         {
             _scanner = scanner;
             _securityService = securityService;
+            _localSettings = localSettings;
             ScanCommand = new Command(OnScanButtonClicked);
             AcceptQrCommand = new Command(OnAcceptQrCommand);
             DenyQrCommand = new Command(OnDenyQrCommand);
@@ -149,16 +151,14 @@ namespace QRBee.ViewModels
 
             var answer = await Application.Current.MainPage.DisplayAlert("Confirmation", "Would you like to accept the offer?", "Yes", "No");
             if (!answer) return;
-
+            var settings = _localSettings.LoadSettings();
             var response = new ClientToMerchantResponse
             {
-                //TODO get client id from database
+                ClientId = settings.ClientId,
-                ClientId = Guid.NewGuid().ToString("D"),
                 TimeStampUTC = DateTime.UtcNow,
-                MerchantRequest = _merchantToClientRequest
+                MerchantRequest = _merchantToClientRequest,
-
+                EncryptedClientCardData = EncryptCardData(settings, _merchantToClientRequest.MerchantTransactionId)
             };
-            // TODO Create client signature.
             var clientSignature = _securityService.Sign(Encoding.UTF8.GetBytes(response.AsDataForSignature()));
             response.ClientSignature = Convert.ToBase64String(clientSignature);
 
@@ -168,13 +168,30 @@ namespace QRBee.ViewModels
             IsScanButtonVisible = true;
         }
 
+        private string EncryptCardData(Settings settings, string transactionId)
+        {
+           var clientCardData = new ClientCardData
+           {
+               TransactionId      = transactionId,
+               CardNumber         = settings.CardNumber,
+               ExpirationDateMMYY = settings.ExpirationDate,
+               ValidFrom          = settings.ValidFrom,
+               CardHolderName     = settings.CardHolderName,
+               CVC                = settings.CVC,
+               IssueNo            = settings.IssueNo
+           };
+
+           var bytes = _securityService.Encrypt(Encoding.UTF8.GetBytes(clientCardData.AsString()),_securityService.APIServerCertificate);
+           return Convert.ToBase64String(bytes);
+        }
+
         public void OnDenyQrCommand(object obj)
         {
-            QrCode = null;
+            QrCode                    = null;
-            IsQrVisible = false;
+            IsQrVisible               = false;
             IsAcceptDenyButtonVisible = false;
-            IsScanButtonVisible = true;
+            IsScanButtonVisible       = true;
-            Amount = "";
+            Amount                    = "";
         }
 
     }

QRBee/QRBee/ViewModels/MerchantPageViewModel.cs

@@ -131,8 +131,7 @@ namespace QRBee.ViewModels
             {
                 var trans = new MerchantToClientRequest
                 {
-                    //TODO get merchant id from database
+                    MerchantId = _settings.LoadSettings().ClientId,
-                    MerchantId = Guid.NewGuid().ToString("D"),
                     MerchantTransactionId = Guid.NewGuid().ToString("D"),
                     Name = Name,
                     Amount = Amount,

QRBee/QRBee/ViewModels/RegisterViewModel.cs

@@ -50,7 +50,7 @@ namespace QRBee.ViewModels
         public string ExpirationDate { get; set; }
         public string CardHolderName { get; set; }
         public string CVC { get; set; }
-        public string IssueNo { get; set; }
+        public int? IssueNo { get; set; }
 
         public Color Password1Color { get; set; }
         public Color Password2Color { get; set;}
@@ -125,7 +125,7 @@ namespace QRBee.ViewModels
 
                 await _settings.SaveSettings(settings);
 
-                if (!_privateKeyHandler.Exists())
+                //if (!_privateKeyHandler.Exists())
                 {
                     _privateKeyHandler.GeneratePrivateKey(settings.Name);
                 }
@@ -149,6 +149,7 @@ namespace QRBee.ViewModels
 
             try
             {
+                //TODO Register if not, otherwise update
                 // FOR TESTING PURPOSES
                 //!settings.IsRegistered
                 if (true)
@@ -158,10 +159,14 @@ namespace QRBee.ViewModels
                     // Save ClientId to LocalSettings
                     settings = _settings.LoadSettings();
                     settings.ClientId = response.ClientId;
+
+                    // Save server public key certificate
+                    _securityService.APIServerCertificate = _securityService.Deserialize(response.APIServerCertificate);
+
                     await _settings.SaveSettings(settings);
 
                     // Attach certificate to privateKey (replace self-sighed with server issued certificate)
-                    _privateKeyHandler.AttachCertificate(_securityService.Deserialize(response.Certificate));
+                    _privateKeyHandler.AttachCertificate(_securityService.Deserialize(response.ClientCertificate));
 
                     var page = Application.Current.MainPage.Navigation.NavigationStack.LastOrDefault();
                     await page.DisplayAlert("Success", "You have been registered successfully", "Ok");

QRBeeApi/Services/QRBeeAPIService.cs

@@ -62,7 +62,8 @@ namespace QRBee.Api.Services
             return new RegistrationResponse
             {
                 ClientId = clientId,
-                Certificate = _securityService.Serialize(clientCertificate)
+                ClientCertificate = _securityService.Serialize(clientCertificate),
+                APIServerCertificate = _securityService.Serialize(_securityService.APIServerCertificate)
             };
         }
 

QRBeeApi/Services/SecurityService.cs

@@ -29,7 +29,10 @@ namespace QRBee.Api.Services
             var req = CreateClientCertRequest(distinguishedName, rsa);
 
             var pk = PrivateKeyHandler.LoadPrivateKey();
-            var clientCert = req.Create(pk,
+            var cert = PrivateKeyHandler.GetCertificate();
+            var newCert = cert.CopyWithPrivateKey(pk);
+
+            var clientCert = req.Create(newCert,
                 DateTimeOffset.UtcNow - TimeSpan.FromDays(1),
                 DateTimeOffset.UtcNow + TimeSpan.FromDays(CertificateValidityPeriodDays),
                 Guid.NewGuid()
@@ -92,6 +95,13 @@ namespace QRBee.Api.Services
 
             return builder.ToString();
         }
+
+        /// <inheritdoc/>
+        public override X509Certificate2 APIServerCertificate
+        {
+            get => PrivateKeyHandler.GetCertificate();
+            set => throw new ApplicationException("Do not call this");
+        }
     }
 
 }

QRBeeApi/Services/ServerPrivateKeyHandler.cs

@@ -55,7 +55,7 @@ namespace QRBee.Api.Services
         public ReadableCertificateRequest CreateCertificateRequest(string subjectName)
         {
             //TODO in fact server should create certificate request in standard format if we ever want to get externally sighed certificate.
-            var pk = LoadPrivateKey();
+            var pk = Load();
             var rsa = pk.GetRSAPrivateKey();
 
             if (rsa == null)
@@ -172,7 +172,7 @@ namespace QRBee.Api.Services
 
 
         /// <inheritdoc/>
-        public X509Certificate2 LoadPrivateKey()
+        private X509Certificate2 Load()
         {
             if (_certificate != null)
                 return _certificate;
@@ -191,6 +191,20 @@ namespace QRBee.Api.Services
             }
         }
 
+        public RSA LoadPrivateKey()
+        {
+            var pk = Load();
+            return pk.GetRSAPrivateKey()?? throw new ApplicationException("Private key not found");
+        }
+
+        public X509Certificate2 GetCertificate()
+        {
+            var pk = Load();
+            var bytes = pk.Export(X509ContentType.Cert);
+            var cert = new X509Certificate2(bytes);
+            return cert;
+        }
+
         /// <inheritdoc/>
         public void AttachCertificate(X509Certificate2 cert)
         {