Feature/validation errors (eu-digital-green-certificates#48)

Added different validation errors logic

Author: oleksandrsarapulovgl

app/src/main/java/dgca/verifier/app/android/verification/VerificationDialogFragment.kt

@@ -44,7 +44,6 @@ import dgca.verifier.app.android.*
 import dgca.verifier.app.android.databinding.DialogFragmentVerificationBinding
 import dgca.verifier.app.android.model.CertificateData
 import dgca.verifier.app.android.model.CertificateModel
-import dgca.verifier.app.decoder.model.VerificationResult
 
 @ExperimentalUnsignedTypes
 @AndroidEntryPoint
@@ -84,9 +83,12 @@ class VerificationDialogFragment : BottomSheetDialogFragment() {
 
         viewModel.verificationResult.observe(viewLifecycleOwner, {
             setCertStatusUI(it.isValid())
-            setCertStatusError(it)
+
             setCertDataVisibility(it.isValid())
         })
+        viewModel.verificationError.observe(viewLifecycleOwner, {
+            setCertStatusError(it)
+        })
         viewModel.certificate.observe(viewLifecycleOwner, { certificate ->
             if (certificate != null) {
                 toggleButton(certificate)
@@ -145,16 +147,17 @@ class VerificationDialogFragment : BottomSheetDialogFragment() {
         binding.actionBtn.isVisible = true
     }
 
-    private fun setCertStatusError(verificationResult: VerificationResult) {
-        if (verificationResult.isSignatureInvalid()) {
-            binding.reasonForCertificateInvalidityTitle.visibility = View.VISIBLE
-            binding.reasonForCertificateInvalidityName.visibility = View.VISIBLE
-            binding.reasonForCertificateInvalidityName.text =
-                getString(R.string.cryptographic_signature_not_valid)
-        } else {
-            binding.reasonForCertificateInvalidityTitle.visibility = View.GONE
-            binding.reasonForCertificateInvalidityName.visibility = View.GONE
-        }
+    private fun setCertStatusError(verificationError: VerificationError) {
+        binding.reasonForCertificateInvalidityTitle.visibility = View.VISIBLE
+        binding.reasonForCertificateInvalidityName.visibility = View.VISIBLE
+        binding.reasonForCertificateInvalidityName.text = getString(
+            when (verificationError) {
+                VerificationError.CERTIFICATE_EXPIRED -> R.string.certificate_is_expired
+                VerificationError.CERTIFICATE_REVOKED -> R.string.certificate_was_revoked
+                VerificationError.VERIFICATION_FAILED -> R.string.verification_failed
+                VerificationError.CRYPTOGRAPHIC_SIGNATURE_INVALID -> R.string.cryptographic_signature_invalid
+            }
+        )
     }
 
     private fun setCertDataVisibility(isValid: Boolean) {

app/src/main/java/dgca/verifier/app/android/verification/VerificationError.kt

@@ -0,0 +1,37 @@
+/*
+ *  ---license-start
+ *  eu-digital-green-certificates / dgca-verifier-app-android
+ *  ---
+ *  Copyright (C) 2021 T-Systems International GmbH and all other contributors
+ *  ---
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *  ---license-end
+ *
+ *  Created by osarapulov on 5/24/21 11:39 PM
+ */
+
+package dgca.verifier.app.android.verification
+
+import dgca.verifier.app.decoder.model.VerificationResult
+
+enum class VerificationError {
+    CERTIFICATE_EXPIRED, CERTIFICATE_REVOKED, VERIFICATION_FAILED, CRYPTOGRAPHIC_SIGNATURE_INVALID
+}
+
+internal fun VerificationResult.fetchError(noPublicKeysFound: Boolean): VerificationError? =
+    when {
+        isValid() -> null
+        !isNotExpired -> VerificationError.CERTIFICATE_EXPIRED
+        noPublicKeysFound -> VerificationError.VERIFICATION_FAILED
+        else -> VerificationError.CRYPTOGRAPHIC_SIGNATURE_INVALID
+    }

app/src/main/java/dgca/verifier/app/android/verification/VerificationViewModel.kt

@@ -62,6 +62,9 @@ class VerificationViewModel @Inject constructor(
     private val _verificationResult = MutableLiveData<VerificationResult>()
     val verificationResult: LiveData<VerificationResult> = _verificationResult
 
+    private val _verificationError = MutableLiveData<VerificationError>()
+    val verificationError: LiveData<VerificationError> = _verificationError
+
     private val _certificate = MutableLiveData<CertificateModel?>()
     val certificate: LiveData<CertificateModel?> = _certificate
 
@@ -77,6 +80,7 @@ class VerificationViewModel @Inject constructor(
             _inProgress.value = true
             var greenCertificate: GreenCertificate? = null
             val verificationResult = VerificationResult()
+            var noPublicKeysFound = true
 
             withContext(Dispatchers.IO) {
                 val plainInput = prefixValidationService.decode(code, verificationResult)
@@ -104,6 +108,7 @@ class VerificationViewModel @Inject constructor(
                     Timber.d("Verification failed: failed to load certificate")
                     return@withContext
                 }
+                noPublicKeysFound = false
                 certificates.forEach { innerCertificate ->
                     cryptoService.validate(cose, innerCertificate, verificationResult)
                     if (verificationResult.coseVerified) {
@@ -112,6 +117,8 @@ class VerificationViewModel @Inject constructor(
                 }
             }
 
+            verificationResult.fetchError(noPublicKeysFound)?.apply { _verificationError.value = this }
+
             _inProgress.value = false
             _verificationResult.value = verificationResult
             _certificate.value = greenCertificate?.toCertificateModel()

app/src/main/res/values/strings.xml

@@ -53,5 +53,8 @@
     <string name="version">Version: %1$s</string>
     <string name="about">About</string>
     <string name="settings_version_title">Verifier App</string>
-    <string name="cryptographic_signature_not_valid">Cryptographic signature not valid.</string>
+    <string name="certificate_is_expired">Certificate is expired.</string>
+    <string name="certificate_was_revoked">Certificate was revoked.</string>
+    <string name="verification_failed">Verification failed.</string>
+    <string name="cryptographic_signature_invalid">Cryptographic signature invalid.</string>
 </resources>