Add initial implementation of Gopenpgp-backed PGP (#1441)

20 files changed, 966 insertions, 4 deletions

diff --git a/app/build.gradle.kts b/app/build.gradle.kts
index c6440adb..a5716989 100644
--- a/app/build.gradle.kts
+++ b/app/build.gradle.kts
@@ -76,6 +76,7 @@ dependencies {
   implementation(libs.androidx.annotation)
   coreLibraryDesugaring(libs.android.desugarJdkLibs)
   implementation(projects.autofillParser)
+  implementation(projects.cryptoPgp)
   implementation(projects.formatCommon)
   implementation(projects.openpgpKtx)
   implementation(libs.androidx.activity.ktx)
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index a2c6003c..98d28f0a 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -45,6 +45,10 @@
       android:windowSoftInputMode="adjustResize" />
 
     <activity
+      android:name=".ui.crypto.GopenpgpDecryptActivity"
+      android:exported="true" />
+
+    <activity
       android:name=".ui.main.LaunchActivity"
       android:configChanges="orientation|screenSize"
       android:label="@string/app_name"
@@ -91,6 +95,10 @@
       android:label="@string/new_password_title"
       android:windowSoftInputMode="adjustResize" />
 
+    <activity android:name=".ui.crypto.GopenpgpPasswordCreationActivity"
+      android:label="@string/new_password_title"
+      android:windowSoftInputMode="adjustResize" />
+
     <activity
       android:name=".ui.crypto.DecryptActivity"
       android:windowSoftInputMode="adjustResize" />
@@ -129,6 +137,9 @@
       android:name=".ui.autofill.AutofillDecryptActivity"
       android:theme="@style/NoBackgroundTheme" />
     <activity
+      android:name=".ui.autofill.GopenpgpAutofillDecryptActivity"
+      android:theme="@style/NoBackgroundTheme" />
+    <activity
       android:name=".ui.autofill.AutofillFilterView"
       android:configChanges="orientation|keyboardHidden"
       android:theme="@style/DialogLikeTheme"
diff --git a/app/src/main/java/dev/msfjarvis/aps/injection/crypto/CryptoHandlerModule.kt b/app/src/main/java/dev/msfjarvis/aps/injection/crypto/CryptoHandlerModule.kt
new file mode 100644
index 00000000..fdd37bf3
--- /dev/null
+++ b/app/src/main/java/dev/msfjarvis/aps/injection/crypto/CryptoHandlerModule.kt
@@ -0,0 +1,31 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+package dev.msfjarvis.aps.injection.crypto
+
+import dagger.Module
+import dagger.Provides
+import dagger.hilt.InstallIn
+import dagger.hilt.components.SingletonComponent
+import dagger.multibindings.IntoSet
+import dev.msfjarvis.aps.data.crypto.CryptoHandler
+import dev.msfjarvis.aps.data.crypto.GopenpgpCryptoHandler
+
+/**
+ * This module adds all [CryptoHandler] implementations into a Set which makes it easier to build
+ * generic UIs which are not tied to a specific implementation because of injection.
+ */
+@Module
+@InstallIn(SingletonComponent::class)
+object CryptoHandlerModule {
+  @Provides
+  @IntoSet
+  fun providePgpCryptoHandler(): CryptoHandler {
+    return GopenpgpCryptoHandler()
+  }
+}
+
+/** Typealias for a [Set] of [CryptoHandler] instances injected by Dagger. */
+typealias CryptoSet = Set<@JvmSuppressWildcards CryptoHandler>
diff --git a/app/src/main/java/dev/msfjarvis/aps/ui/autofill/AutofillFilterActivity.kt b/app/src/main/java/dev/msfjarvis/aps/ui/autofill/AutofillFilterActivity.kt
index afa2a6a0..1d5160e2 100644
--- a/app/src/main/java/dev/msfjarvis/aps/ui/autofill/AutofillFilterActivity.kt
+++ b/app/src/main/java/dev/msfjarvis/aps/ui/autofill/AutofillFilterActivity.kt
@@ -29,6 +29,7 @@ import com.github.androidpasswordstore.autofillparser.FormOrigin
 import dev.msfjarvis.aps.R
 import dev.msfjarvis.aps.data.password.PasswordItem
 import dev.msfjarvis.aps.databinding.ActivityOreoAutofillFilterBinding
+import dev.msfjarvis.aps.util.FeatureFlags
 import dev.msfjarvis.aps.util.autofill.AutofillMatcher
 import dev.msfjarvis.aps.util.autofill.AutofillPreferences
 import dev.msfjarvis.aps.util.autofill.DirectoryStructure
@@ -220,7 +221,11 @@ class AutofillFilterView : AppCompatActivity() {
       AutofillMatcher.addMatchFor(applicationContext, formOrigin, item.file)
     // intent?.extras? is checked to be non-null in onCreate
     decryptAction.launch(
-      AutofillDecryptActivity.makeDecryptFileIntent(item.file, intent!!.extras!!, this)
+      if (FeatureFlags.ENABLE_GOPENPGP) {
+        GopenpgpAutofillDecryptActivity.makeDecryptFileIntent(item.file, intent!!.extras!!, this)
+      } else {
+        AutofillDecryptActivity.makeDecryptFileIntent(item.file, intent!!.extras!!, this)
+      }
     )
   }
 }
diff --git a/app/src/main/java/dev/msfjarvis/aps/ui/autofill/GopenpgpAutofillDecryptActivity.kt b/app/src/main/java/dev/msfjarvis/aps/ui/autofill/GopenpgpAutofillDecryptActivity.kt
new file mode 100644
index 00000000..1c9f19d7
--- /dev/null
+++ b/app/src/main/java/dev/msfjarvis/aps/ui/autofill/GopenpgpAutofillDecryptActivity.kt
@@ -0,0 +1,155 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+package dev.msfjarvis.aps.ui.autofill
+
+import android.app.PendingIntent
+import android.content.Context
+import android.content.Intent
+import android.content.IntentSender
+import android.os.Build
+import android.os.Bundle
+import android.view.autofill.AutofillManager
+import androidx.annotation.RequiresApi
+import androidx.appcompat.app.AppCompatActivity
+import androidx.lifecycle.lifecycleScope
+import com.github.ajalt.timberkt.d
+import com.github.ajalt.timberkt.e
+import com.github.androidpasswordstore.autofillparser.AutofillAction
+import com.github.androidpasswordstore.autofillparser.Credentials
+import com.github.michaelbull.result.getOrElse
+import com.github.michaelbull.result.onFailure
+import com.github.michaelbull.result.onSuccess
+import com.github.michaelbull.result.runCatching
+import dagger.hilt.android.AndroidEntryPoint
+import dev.msfjarvis.aps.injection.crypto.CryptoSet
+import dev.msfjarvis.aps.injection.password.PasswordEntryFactory
+import dev.msfjarvis.aps.ui.crypto.GopenpgpDecryptActivity
+import dev.msfjarvis.aps.util.autofill.AutofillPreferences
+import dev.msfjarvis.aps.util.autofill.AutofillResponseBuilder
+import dev.msfjarvis.aps.util.autofill.DirectoryStructure
+import java.io.File
+import javax.inject.Inject
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+
+@RequiresApi(Build.VERSION_CODES.O)
+@AndroidEntryPoint
+class GopenpgpAutofillDecryptActivity : AppCompatActivity() {
+
+  companion object {
+
+    private const val EXTRA_FILE_PATH = "dev.msfjarvis.aps.autofill.oreo.EXTRA_FILE_PATH"
+    private const val EXTRA_SEARCH_ACTION = "dev.msfjarvis.aps.autofill.oreo.EXTRA_SEARCH_ACTION"
+
+    private var decryptFileRequestCode = 1
+
+    fun makeDecryptFileIntent(file: File, forwardedExtras: Bundle, context: Context): Intent {
+      return Intent(context, GopenpgpAutofillDecryptActivity::class.java).apply {
+        putExtras(forwardedExtras)
+        putExtra(EXTRA_SEARCH_ACTION, true)
+        putExtra(EXTRA_FILE_PATH, file.absolutePath)
+      }
+    }
+
+    fun makeDecryptFileIntentSender(file: File, context: Context): IntentSender {
+      val intent =
+        Intent(context, GopenpgpAutofillDecryptActivity::class.java).apply {
+          putExtra(EXTRA_SEARCH_ACTION, false)
+          putExtra(EXTRA_FILE_PATH, file.absolutePath)
+        }
+      return PendingIntent.getActivity(
+          context,
+          decryptFileRequestCode++,
+          intent,
+          PendingIntent.FLAG_CANCEL_CURRENT
+        )
+        .intentSender
+    }
+  }
+
+  @Inject lateinit var passwordEntryFactory: PasswordEntryFactory
+  @Inject lateinit var cryptos: CryptoSet
+
+  private lateinit var directoryStructure: DirectoryStructure
+
+  override fun onStart() {
+    super.onStart()
+    val filePath =
+      intent?.getStringExtra(EXTRA_FILE_PATH)
+        ?: run {
+          e { "GopenpgpAutofillDecryptActivity started without EXTRA_FILE_PATH" }
+          finish()
+          return
+        }
+    val clientState =
+      intent?.getBundleExtra(AutofillManager.EXTRA_CLIENT_STATE)
+        ?: run {
+          e { "GopenpgpAutofillDecryptActivity started without EXTRA_CLIENT_STATE" }
+          finish()
+          return
+        }
+    val isSearchAction = intent?.getBooleanExtra(EXTRA_SEARCH_ACTION, true)!!
+    val action = if (isSearchAction) AutofillAction.Search else AutofillAction.Match
+    directoryStructure = AutofillPreferences.directoryStructure(this)
+    d { action.toString() }
+    lifecycleScope.launch {
+      val credentials = decryptCredential(File(filePath))
+      if (credentials == null) {
+        setResult(RESULT_CANCELED)
+      } else {
+        val fillInDataset =
+          AutofillResponseBuilder.makeFillInDataset(
+            this@GopenpgpAutofillDecryptActivity,
+            credentials,
+            clientState,
+            action
+          )
+        withContext(Dispatchers.Main) {
+          setResult(
+            RESULT_OK,
+            Intent().apply { putExtra(AutofillManager.EXTRA_AUTHENTICATION_RESULT, fillInDataset) }
+          )
+        }
+      }
+      withContext(Dispatchers.Main) { finish() }
+    }
+  }
+
+  private suspend fun decryptCredential(file: File): Credentials? {
+    runCatching { file.inputStream() }
+      .onFailure { e ->
+        e(e) { "File to decrypt not found" }
+        return null
+      }
+      .onSuccess { encryptedInput ->
+        runCatching {
+          val crypto = cryptos.first { it.canHandle(file.absolutePath) }
+          withContext(Dispatchers.IO) {
+            crypto.decrypt(
+              GopenpgpDecryptActivity.PRIV_KEY,
+              GopenpgpDecryptActivity.PASS.toByteArray(charset = Charsets.UTF_8),
+              encryptedInput.readBytes()
+            )
+          }
+        }
+          .onFailure { e ->
+            e(e) { "Decryption with Gopenpgp failed" }
+            return null
+          }
+          .onSuccess { result ->
+            return runCatching {
+              val entry = passwordEntryFactory.create(lifecycleScope, result)
+              AutofillPreferences.credentialsFromStoreEntry(this, file, entry, directoryStructure)
+            }
+              .getOrElse { e ->
+                e(e) { "Failed to parse password entry" }
+                return null
+              }
+          }
+      }
+    return null
+  }
+}
diff --git a/app/src/main/java/dev/msfjarvis/aps/ui/crypto/GopenpgpDecryptActivity.kt b/app/src/main/java/dev/msfjarvis/aps/ui/crypto/GopenpgpDecryptActivity.kt
new file mode 100644
index 00000000..b2e710f8
--- /dev/null
+++ b/app/src/main/java/dev/msfjarvis/aps/ui/crypto/GopenpgpDecryptActivity.kt
@@ -0,0 +1,177 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+package dev.msfjarvis.aps.ui.crypto
+
+import android.content.Intent
+import android.os.Bundle
+import android.view.Menu
+import android.view.MenuItem
+import androidx.lifecycle.lifecycleScope
+import dagger.hilt.android.AndroidEntryPoint
+import dev.msfjarvis.aps.R
+import dev.msfjarvis.aps.data.passfile.PasswordEntry
+import dev.msfjarvis.aps.data.password.FieldItem
+import dev.msfjarvis.aps.databinding.DecryptLayoutBinding
+import dev.msfjarvis.aps.injection.crypto.CryptoSet
+import dev.msfjarvis.aps.injection.password.PasswordEntryFactory
+import dev.msfjarvis.aps.ui.adapters.FieldItemAdapter
+import dev.msfjarvis.aps.util.extensions.unsafeLazy
+import dev.msfjarvis.aps.util.extensions.viewBinding
+import java.io.File
+import javax.inject.Inject
+import kotlin.time.Duration
+import kotlin.time.ExperimentalTime
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+
+@AndroidEntryPoint
+class GopenpgpDecryptActivity : BasePgpActivity() {
+
+  private val binding by viewBinding(DecryptLayoutBinding::inflate)
+  @Inject lateinit var passwordEntryFactory: PasswordEntryFactory
+  @Inject lateinit var cryptos: CryptoSet
+  private val relativeParentPath by unsafeLazy { getParentPath(fullPath, repoPath) }
+
+  private var passwordEntry: PasswordEntry? = null
+
+  override fun onCreate(savedInstanceState: Bundle?) {
+    super.onCreate(savedInstanceState)
+    supportActionBar?.setDisplayHomeAsUpEnabled(true)
+    title = name
+    with(binding) {
+      setContentView(root)
+      passwordCategory.text = relativeParentPath
+      passwordFile.text = name
+      passwordFile.setOnLongClickListener {
+        copyTextToClipboard(name)
+        true
+      }
+    }
+    decrypt()
+  }
+
+  override fun onCreateOptionsMenu(menu: Menu?): Boolean {
+    menuInflater.inflate(R.menu.pgp_handler, menu)
+    passwordEntry?.let { entry ->
+      if (menu != null) {
+        menu.findItem(R.id.edit_password).isVisible = true
+        if (!entry.password.isNullOrBlank()) {
+          menu.findItem(R.id.share_password_as_plaintext).isVisible = true
+          menu.findItem(R.id.copy_password).isVisible = true
+        }
+      }
+    }
+    return true
+  }
+
+  override fun onOptionsItemSelected(item: MenuItem): Boolean {
+    when (item.itemId) {
+      android.R.id.home -> onBackPressed()
+      R.id.edit_password -> editPassword()
+      R.id.share_password_as_plaintext -> shareAsPlaintext()
+      R.id.copy_password -> copyPasswordToClipboard(passwordEntry?.password)
+      else -> return super.onOptionsItemSelected(item)
+    }
+    return true
+  }
+
+  /**
+   * Automatically finishes the activity 60 seconds after decryption succeeded to prevent
+   * information leaks from stale activities.
+   */
+  @OptIn(ExperimentalTime::class)
+  private fun startAutoDismissTimer() {
+    lifecycleScope.launch {
+      delay(Duration.seconds(60))
+      finish()
+    }
+  }
+
+  /**
+   * Edit the current password and hide all the fields populated by encrypted data so that when the
+   * result triggers they can be repopulated with new data.
+   */
+  private fun editPassword() {
+    val intent = Intent(this, PasswordCreationActivity::class.java)
+    intent.putExtra("FILE_PATH", relativeParentPath)
+    intent.putExtra("REPO_PATH", repoPath)
+    intent.putExtra(PasswordCreationActivity.EXTRA_FILE_NAME, name)
+    intent.putExtra(PasswordCreationActivity.EXTRA_PASSWORD, passwordEntry?.password)
+    intent.putExtra(PasswordCreationActivity.EXTRA_EXTRA_CONTENT, passwordEntry?.extraContentString)
+    intent.putExtra(PasswordCreationActivity.EXTRA_EDITING, true)
+    startActivity(intent)
+    finish()
+  }
+
+  private fun shareAsPlaintext() {
+    val sendIntent =
+      Intent().apply {
+        action = Intent.ACTION_SEND
+        putExtra(Intent.EXTRA_TEXT, passwordEntry?.password)
+        type = "text/plain"
+      }
+    // Always show a picker to give the user a chance to cancel
+    startActivity(
+      Intent.createChooser(sendIntent, resources.getText(R.string.send_plaintext_password_to))
+    )
+  }
+
+  private fun decrypt() {
+    lifecycleScope.launch {
+      // TODO(msfjarvis): native methods are fallible, add error handling once out of testing
+      val message = withContext(Dispatchers.IO) { File(fullPath).readBytes() }
+      val result =
+        withContext(Dispatchers.IO) {
+          val crypto = cryptos.first { it.canHandle(fullPath) }
+          crypto.decrypt(
+            PRIV_KEY,
+            PASS.toByteArray(charset = Charsets.UTF_8),
+            message,
+          )
+        }
+      startAutoDismissTimer()
+
+      val entry = passwordEntryFactory.create(lifecycleScope, result)
+      passwordEntry = entry
+      invalidateOptionsMenu()
+
+      val items = arrayListOf<FieldItem>()
+      val adapter = FieldItemAdapter(emptyList(), true) { text -> copyTextToClipboard(text) }
+      if (!entry.password.isNullOrBlank()) {
+        items.add(FieldItem.createPasswordField(entry.password!!))
+      }
+
+      if (entry.hasTotp()) {
+        lifecycleScope.launch {
+          items.add(FieldItem.createOtpField(entry.totp.value))
+          entry.totp.collect { code ->
+            withContext(Dispatchers.Main) { adapter.updateOTPCode(code) }
+          }
+        }
+      }
+
+      if (!entry.username.isNullOrBlank()) {
+        items.add(FieldItem.createUsernameField(entry.username!!))
+      }
+
+      entry.extraContent.forEach { (key, value) ->
+        items.add(FieldItem(key, value, FieldItem.ActionType.COPY))
+      }
+
+      binding.recyclerView.adapter = adapter
+      adapter.updateItems(items)
+    }
+  }
+
+  companion object {
+    // TODO(msfjarvis): source these from storage and user input
+    const val PRIV_KEY = ""
+    const val PASS = ""
+  }
+}
diff --git a/app/src/main/java/dev/msfjarvis/aps/ui/crypto/GopenpgpPasswordCreationActivity.kt b/app/src/main/java/dev/msfjarvis/aps/ui/crypto/GopenpgpPasswordCreationActivity.kt
new file mode 100644
index 00000000..2228a758
--- /dev/null
+++ b/app/src/main/java/dev/msfjarvis/aps/ui/crypto/GopenpgpPasswordCreationActivity.kt
@@ -0,0 +1,432 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+package dev.msfjarvis.aps.ui.crypto
+
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.os.Bundle
+import android.text.InputType
+import android.view.Menu
+import android.view.MenuItem
+import android.view.View
+import androidx.activity.result.contract.ActivityResultContracts.StartActivityForResult
+import androidx.core.content.edit
+import androidx.core.view.isVisible
+import androidx.core.widget.doOnTextChanged
+import androidx.lifecycle.lifecycleScope
+import com.github.ajalt.timberkt.e
+import com.github.michaelbull.result.onFailure
+import com.github.michaelbull.result.onSuccess
+import com.github.michaelbull.result.runCatching
+import com.google.android.material.dialog.MaterialAlertDialogBuilder
+import com.google.zxing.integration.android.IntentIntegrator
+import com.google.zxing.integration.android.IntentIntegrator.QR_CODE
+import dagger.hilt.android.AndroidEntryPoint
+import dev.msfjarvis.aps.R
+import dev.msfjarvis.aps.databinding.PasswordCreationActivityBinding
+import dev.msfjarvis.aps.injection.crypto.CryptoSet
+import dev.msfjarvis.aps.injection.password.PasswordEntryFactory
+import dev.msfjarvis.aps.ui.dialogs.OtpImportDialogFragment
+import dev.msfjarvis.aps.ui.dialogs.PasswordGeneratorDialogFragment
+import dev.msfjarvis.aps.ui.dialogs.XkPasswordGeneratorDialogFragment
+import dev.msfjarvis.aps.util.autofill.AutofillPreferences
+import dev.msfjarvis.aps.util.autofill.DirectoryStructure
+import dev.msfjarvis.aps.util.extensions.base64
+import dev.msfjarvis.aps.util.extensions.commitChange
+import dev.msfjarvis.aps.util.extensions.getString
+import dev.msfjarvis.aps.util.extensions.isInsideRepository
+import dev.msfjarvis.aps.util.extensions.snackbar
+import dev.msfjarvis.aps.util.extensions.unsafeLazy
+import dev.msfjarvis.aps.util.extensions.viewBinding
+import dev.msfjarvis.aps.util.settings.PreferenceKeys
+import java.io.File
+import java.io.IOException
+import javax.inject.Inject
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+
+@AndroidEntryPoint
+class GopenpgpPasswordCreationActivity : BasePgpActivity() {
+
+  private val binding by viewBinding(PasswordCreationActivityBinding::inflate)
+  @Inject lateinit var passwordEntryFactory: PasswordEntryFactory
+  @Inject lateinit var cryptos: CryptoSet
+
+  private val suggestedName by unsafeLazy { intent.getStringExtra(EXTRA_FILE_NAME) }
+  private val suggestedPass by unsafeLazy { intent.getStringExtra(EXTRA_PASSWORD) }
+  private val suggestedExtra by unsafeLazy { intent.getStringExtra(EXTRA_EXTRA_CONTENT) }
+  private val shouldGeneratePassword by unsafeLazy {
+    intent.getBooleanExtra(EXTRA_GENERATE_PASSWORD, false)
+  }
+  private val editing by unsafeLazy { intent.getBooleanExtra(EXTRA_EDITING, false) }
+  private val oldFileName by unsafeLazy { intent.getStringExtra(EXTRA_FILE_NAME) }
+  private var oldCategory: String? = null
+  private var copy: Boolean = false
+
+  private val otpImportAction =
+    registerForActivityResult(StartActivityForResult()) { result ->
+      if (result.resultCode == RESULT_OK) {
+        binding.otpImportButton.isVisible = false
+        val intentResult = IntentIntegrator.parseActivityResult(RESULT_OK, result.data)
+        val contents = "${intentResult.contents}\n"
+        val currentExtras = binding.extraContent.text.toString()
+        if (currentExtras.isNotEmpty() && currentExtras.last() != '\n')
+          binding.extraContent.append("\n$contents")
+        else binding.extraContent.append(contents)
+        snackbar(message = getString(R.string.otp_import_success))
+      } else {
+        snackbar(message = getString(R.string.otp_import_failure))
+      }
+    }
+
+  override fun onCreate(savedInstanceState: Bundle?) {
+    super.onCreate(savedInstanceState)
+    supportActionBar?.setDisplayHomeAsUpEnabled(true)
+    bindToOpenKeychain(this)
+    title =
+      if (editing) getString(R.string.edit_password) else getString(R.string.new_password_title)
+    with(binding) {
+      setContentView(root)
+      generatePassword.setOnClickListener { generatePassword() }
+      otpImportButton.setOnClickListener {
+        supportFragmentManager.setFragmentResultListener(
+          OTP_RESULT_REQUEST_KEY,
+          this@GopenpgpPasswordCreationActivity
+        ) { requestKey, bundle ->
+          if (requestKey == OTP_RESULT_REQUEST_KEY) {
+            val contents = bundle.getString(RESULT)
+            val currentExtras = binding.extraContent.text.toString()
+            if (currentExtras.isNotEmpty() && currentExtras.last() != '\n')
+              binding.extraContent.append("\n$contents")
+            else binding.extraContent.append(contents)
+          }
+        }
+        val hasCamera = packageManager?.hasSystemFeature(PackageManager.FEATURE_CAMERA_ANY) == true
+        if (hasCamera) {
+          val items =
+            arrayOf(
+              getString(R.string.otp_import_qr_code),
+              getString(R.string.otp_import_manual_entry)
+            )
+          MaterialAlertDialogBuilder(this@GopenpgpPasswordCreationActivity)
+            .setItems(items) { _, index ->
+              when (index) {
+                0 ->
+                  otpImportAction.launch(
+                    IntentIntegrator(this@GopenpgpPasswordCreationActivity)
+                      .setOrientationLocked(false)
+                      .setBeepEnabled(false)
+                      .setDesiredBarcodeFormats(QR_CODE)
+                      .createScanIntent()
+                  )
+                1 -> OtpImportDialogFragment().show(supportFragmentManager, "OtpImport")
+              }
+            }
+            .show()
+        } else {
+          OtpImportDialogFragment().show(supportFragmentManager, "OtpImport")
+        }
+      }
+
+      directoryInputLayout.apply {
+        if (suggestedName != null || suggestedPass != null || shouldGeneratePassword) {
+          isEnabled = true
+        } else {
+          setBackgroundColor(getColor(android.R.color.transparent))
+        }
+        val path = getRelativePath(fullPath, repoPath)
+        // Keep empty path field visible if it is editable.
+        if (path.isEmpty() && !isEnabled) visibility = View.GONE
+        else {
+          directory.setText(path)
+          oldCategory = path
+        }
+      }
+      if (suggestedName != null) {
+        filename.setText(suggestedName)
+      } else {
+        filename.requestFocus()
+      }
+      // Allow the user to quickly switch between storing the username as the filename or
+      // in the encrypted extras. This only makes sense if the directory structure is
+      // FileBased.
+      if (suggestedName == null &&
+          AutofillPreferences.directoryStructure(this@GopenpgpPasswordCreationActivity) ==
+            DirectoryStructure.FileBased
+      ) {
+        encryptUsername.apply {
+          visibility = View.VISIBLE
+          setOnClickListener {
+            if (isChecked) {
+              // User wants to enable username encryption, so we add it to the
+              // encrypted extras as the first line.
+              val username = filename.text.toString()
+              val extras = "username:$username\n${extraContent.text}"
+
+              filename.text?.clear()
+              extraContent.setText(extras)
+            } else {
+              // User wants to disable username encryption, so we extract the
+              // username from the encrypted extras and use it as the filename.
+              val entry =
+                passwordEntryFactory.create(
+                  lifecycleScope,
+                  "PASSWORD\n${extraContent.text}".encodeToByteArray()
+                )
+              val username = entry.username
+
+              // username should not be null here by the logic in
+              // updateViewState, but it could still happen due to
+              // input lag.
+              if (username != null) {
+                filename.setText(username)
+                extraContent.setText(entry.extraContentWithoutAuthData)
+              }
+            }
+          }
+        }
+        listOf(filename, extraContent).forEach {
+          it.doOnTextChanged { _, _, _, _ -> updateViewState() }
+        }
+      }
+      suggestedPass?.let {
+        password.setText(it)
+        password.inputType = InputType.TYPE_CLASS_TEXT or InputType.TYPE_TEXT_VARIATION_PASSWORD
+      }
+      suggestedExtra?.let { extraContent.setText(it) }
+      if (shouldGeneratePassword) {
+        generatePassword()
+        password.inputType = InputType.TYPE_CLASS_TEXT or InputType.TYPE_TEXT_VARIATION_PASSWORD
+      }
+    }
+    updateViewState()
+  }
+
+  override fun onCreateOptionsMenu(menu: Menu?): Boolean {
+    menuInflater.inflate(R.menu.pgp_handler_new_password, menu)
+    return true
+  }
+
+  override fun onOptionsItemSelected(item: MenuItem): Boolean {
+    when (item.itemId) {
+      android.R.id.home -> {
+        setResult(RESULT_CANCELED)
+        onBackPressed()
+      }
+      R.id.save_password -> {
+        copy = false
+        encrypt()
+      }
+      R.id.save_and_copy_password -> {
+        copy = true
+        encrypt()
+      }
+      else -> return super.onOptionsItemSelected(item)
+    }
+    return true
+  }
+
+  private fun generatePassword() {
+    supportFragmentManager.setFragmentResultListener(PASSWORD_RESULT_REQUEST_KEY, this) {
+      requestKey,
+      bundle ->
+      if (requestKey == PASSWORD_RESULT_REQUEST_KEY) {
+        binding.password.setText(bundle.getString(RESULT))
+      }
+    }
+    when (settings.getString(PreferenceKeys.PREF_KEY_PWGEN_TYPE) ?: KEY_PWGEN_TYPE_CLASSIC) {
+      KEY_PWGEN_TYPE_CLASSIC ->
+        PasswordGeneratorDialogFragment().show(supportFragmentManager, "generator")
+      KEY_PWGEN_TYPE_XKPASSWD ->
+        XkPasswordGeneratorDialogFragment().show(supportFragmentManager, "xkpwgenerator")
+    }
+  }
+
+  private fun updateViewState() =
+    with(binding) {
+      // Use PasswordEntry to parse extras for username
+      val entry =
+        passwordEntryFactory.create(
+          lifecycleScope,
+          "PLACEHOLDER\n${extraContent.text}".encodeToByteArray()
+        )
+      encryptUsername.apply {
+        if (visibility != View.VISIBLE) return@apply
+        val hasUsernameInFileName = filename.text.toString().isNotBlank()
+        val hasUsernameInExtras = !entry.username.isNullOrBlank()
+        isEnabled = hasUsernameInFileName xor hasUsernameInExtras
+        isChecked = hasUsernameInExtras
+      }
+      otpImportButton.isVisible = !entry.hasTotp()
+    }
+
+  /** Encrypts the password and the extra content */
+  private fun encrypt() {
+    with(binding) {
+      val editName = filename.text.toString().trim()
+      val editPass = password.text.toString()
+      val editExtra = extraContent.text.toString()
+
+      if (editName.isEmpty()) {
+        snackbar(message = resources.getString(R.string.file_toast_text))
+        return@with
+      } else if (editName.contains('/')) {
+        snackbar(message = resources.getString(R.string.invalid_filename_text))
+        return@with
+      }
+
+      if (editPass.isEmpty() && editExtra.isEmpty()) {
+        snackbar(message = resources.getString(R.string.empty_toast_text))
+        return@with
+      }
+
+      if (copy) {
+        copyPasswordToClipboard(editPass)
+      }
+
+      val content = "$editPass\n$editExtra"
+      val path =
+        when {
+          // If we allowed the user to edit the relative path, we have to consider it here
+          // instead
+          // of fullPath.
+          directoryInputLayout.isEnabled -> {
+            val editRelativePath = directory.text.toString().trim()
+            if (editRelativePath.isEmpty()) {
+              snackbar(message = resources.getString(R.string.path_toast_text))
+              return
+            }
+            val passwordDirectory = File("$repoPath/${editRelativePath.trim('/')}")
+            if (!passwordDirectory.exists() && !passwordDirectory.mkdir()) {
+              snackbar(message = "Failed to create directory ${editRelativePath.trim('/')}")
+              return
+            }
+
+            "${passwordDirectory.path}/$editName.gpg"
+          }
+          else -> "$fullPath/$editName.gpg"
+        }
+
+      lifecycleScope.launch(Dispatchers.Main) {
+        runCatching {
+          val crypto = cryptos.first { it.canHandle(path) }
+          val result =
+            withContext(Dispatchers.IO) { crypto.encrypt(PUB_KEY, content.encodeToByteArray()) }
+          val file = File(path)
+          // If we're not editing, this file should not already exist!
+          // Additionally, if we were editing and the incoming and outgoing
+          // filenames differ, it means we renamed. Ensure that the target
+          // doesn't already exist to prevent an accidental overwrite.
+          if ((!editing || (editing && suggestedName != file.nameWithoutExtension)) && file.exists()
+          ) {
+            snackbar(message = getString(R.string.password_creation_duplicate_error))
+            return@runCatching
+          }
+
+          if (!file.isInsideRepository()) {
+            snackbar(message = getString(R.string.message_error_destination_outside_repo))
+            return@runCatching
+          }
+
+          withContext(Dispatchers.IO) { file.outputStream().use { it.write(result) } }
+
+          // associate the new password name with the last name's timestamp in
+          // history
+          val preference = getSharedPreferences("recent_password_history", Context.MODE_PRIVATE)
+          val oldFilePathHash = "$repoPath/${oldCategory?.trim('/')}/$oldFileName.gpg".base64()
+          val timestamp = preference.getString(oldFilePathHash)
+          if (timestamp != null) {
+            preference.edit {
+              remove(oldFilePathHash)
+              putString(file.absolutePath.base64(), timestamp)
+            }
+          }
+
+          val returnIntent = Intent()
+          returnIntent.putExtra(RETURN_EXTRA_CREATED_FILE, path)
+          returnIntent.putExtra(RETURN_EXTRA_NAME, editName)
+          returnIntent.putExtra(RETURN_EXTRA_LONG_NAME, getLongName(fullPath, repoPath, editName))
+
+          if (shouldGeneratePassword) {
+            val directoryStructure = AutofillPreferences.directoryStructure(applicationContext)
+            val entry = passwordEntryFactory.create(lifecycleScope, content.encodeToByteArray())
+            returnIntent.putExtra(RETURN_EXTRA_PASSWORD, entry.password)
+            val username = entry.username ?: directoryStructure.getUsernameFor(file)
+            returnIntent.putExtra(RETURN_EXTRA_USERNAME, username)
+          }
+
+          if (directoryInputLayout.isVisible &&
+              directoryInputLayout.isEnabled &&
+              oldFileName != null
+          ) {
+            val oldFile = File("$repoPath/${oldCategory?.trim('/')}/$oldFileName.gpg")
+            if (oldFile.path != file.path && !oldFile.delete()) {
+              setResult(RESULT_CANCELED)
+              MaterialAlertDialogBuilder(this@GopenpgpPasswordCreationActivity)
+                .setTitle(R.string.password_creation_file_fail_title)
+                .setMessage(
+                  getString(R.string.password_creation_file_delete_fail_message, oldFileName)
+                )
+                .setCancelable(false)
+                .setPositiveButton(android.R.string.ok) { _, _ -> finish() }
+                .show()
+              return@runCatching
+            }
+          }
+
+          val commitMessageRes =
+            if (editing) R.string.git_commit_edit_text else R.string.git_commit_add_text
+          lifecycleScope.launch {
+            commitChange(
+              resources.getString(commitMessageRes, getLongName(fullPath, repoPath, editName))
+            )
+              .onSuccess {
+                setResult(RESULT_OK, returnIntent)
+                finish()
+              }
+          }
+        }
+          .onFailure { e ->
+            if (e is IOException) {
+              e(e) { "Failed to write password file" }
+              setResult(RESULT_CANCELED)
+              MaterialAlertDialogBuilder(this@GopenpgpPasswordCreationActivity)
+                .setTitle(getString(R.string.password_creation_file_fail_title))
+                .setMessage(getString(R.string.password_creation_file_write_fail_message))
+                .setCancelable(false)
+                .setPositiveButton(android.R.string.ok) { _, _ -> finish() }
+                .show()
+            } else {
+              e(e)
+            }
+          }
+      }
+    }
+  }
+
+  companion object {
+
+    private const val KEY_PWGEN_TYPE_CLASSIC = "classic"
+    private const val KEY_PWGEN_TYPE_XKPASSWD = "xkpasswd"
+    const val PASSWORD_RESULT_REQUEST_KEY = "PASSWORD_GENERATOR"
+    const val OTP_RESULT_REQUEST_KEY = "OTP_IMPORT"
+    const val RESULT = "RESULT"
+    const val RETURN_EXTRA_CREATED_FILE = "CREATED_FILE"
+    const val RETURN_EXTRA_NAME = "NAME"
+    const val RETURN_EXTRA_LONG_NAME = "LONG_NAME"
+    const val RETURN_EXTRA_USERNAME = "USERNAME"
+    const val RETURN_EXTRA_PASSWORD = "PASSWORD"
+    const val EXTRA_FILE_NAME = "FILENAME"
+    const val EXTRA_PASSWORD = "PASSWORD"
+    const val EXTRA_EXTRA_CONTENT = "EXTRA_CONTENT"
+    const val EXTRA_GENERATE_PASSWORD = "GENERATE_PASSWORD"
+    const val EXTRA_EDITING = "EDITING"
+    // TODO(msfjarvis): source this from storage
+    const val PUB_KEY = ""
+  }
+}
diff --git a/app/src/main/java/dev/msfjarvis/aps/ui/passwords/PasswordStore.kt b/app/src/main/java/dev/msfjarvis/aps/ui/passwords/PasswordStore.kt
index 892289af..38c97f36 100644
--- a/app/src/main/java/dev/msfjarvis/aps/ui/passwords/PasswordStore.kt
+++ b/app/src/main/java/dev/msfjarvis/aps/ui/passwords/PasswordStore.kt
@@ -38,6 +38,7 @@ import dev.msfjarvis.aps.data.password.PasswordItem
 import dev.msfjarvis.aps.data.repo.PasswordRepository
 import dev.msfjarvis.aps.ui.crypto.BasePgpActivity.Companion.getLongName
 import dev.msfjarvis.aps.ui.crypto.DecryptActivity
+import dev.msfjarvis.aps.ui.crypto.GopenpgpDecryptActivity
 import dev.msfjarvis.aps.ui.crypto.PasswordCreationActivity
 import dev.msfjarvis.aps.ui.dialogs.BasicBottomSheet
 import dev.msfjarvis.aps.ui.dialogs.FolderCreationDialogFragment
@@ -46,6 +47,7 @@ import dev.msfjarvis.aps.ui.git.base.BaseGitActivity
 import dev.msfjarvis.aps.ui.onboarding.activity.OnboardingActivity
 import dev.msfjarvis.aps.ui.settings.DirectorySelectionActivity
 import dev.msfjarvis.aps.ui.settings.SettingsActivity
+import dev.msfjarvis.aps.util.FeatureFlags
 import dev.msfjarvis.aps.util.autofill.AutofillMatcher
 import dev.msfjarvis.aps.util.extensions.base64
 import dev.msfjarvis.aps.util.extensions.commitChange
@@ -422,7 +424,14 @@ class PasswordStore : BaseGitActivity() {
     val authDecryptIntent = item.createAuthEnabledIntent(this)
     val decryptIntent =
       (authDecryptIntent.clone() as Intent).setComponent(
-        ComponentName(this, DecryptActivity::class.java)
+        ComponentName(
+          this,
+          if (FeatureFlags.ENABLE_GOPENPGP) {
+            GopenpgpDecryptActivity::class.java
+          } else {
+            DecryptActivity::class.java
+          }
+        )
       )
 
     startActivity(decryptIntent)
diff --git a/app/src/main/java/dev/msfjarvis/aps/util/FeatureFlags.kt b/app/src/main/java/dev/msfjarvis/aps/util/FeatureFlags.kt
new file mode 100644
index 00000000..09544267
--- /dev/null
+++ b/app/src/main/java/dev/msfjarvis/aps/util/FeatureFlags.kt
@@ -0,0 +1,6 @@
+package dev.msfjarvis.aps.util
+
+/** Naive feature flagging functionality to allow merging incomplete features */
+object FeatureFlags {
+  const val ENABLE_GOPENPGP = false
+}
diff --git a/app/src/main/java/dev/msfjarvis/aps/util/autofill/Api30AutofillResponseBuilder.kt b/app/src/main/java/dev/msfjarvis/aps/util/autofill/Api30AutofillResponseBuilder.kt
index ea03bb23..80891f3a 100644
--- a/app/src/main/java/dev/msfjarvis/aps/util/autofill/Api30AutofillResponseBuilder.kt
+++ b/app/src/main/java/dev/msfjarvis/aps/util/autofill/Api30AutofillResponseBuilder.kt
@@ -25,6 +25,8 @@ import dev.msfjarvis.aps.ui.autofill.AutofillDecryptActivity
 import dev.msfjarvis.aps.ui.autofill.AutofillFilterView
 import dev.msfjarvis.aps.ui.autofill.AutofillPublisherChangedActivity
 import dev.msfjarvis.aps.ui.autofill.AutofillSaveActivity
+import dev.msfjarvis.aps.ui.autofill.GopenpgpAutofillDecryptActivity
+import dev.msfjarvis.aps.util.FeatureFlags
 import java.io.File
 
 /** Implements [AutofillResponseBuilder]'s methods for API 30 and above */
@@ -68,7 +70,12 @@ class Api30AutofillResponseBuilder(form: FillableForm) {
   ): Dataset? {
     if (!scenario.hasFieldsToFillOn(AutofillAction.Match)) return null
     val metadata = makeFillMatchMetadata(context, file)
-    val intentSender = AutofillDecryptActivity.makeDecryptFileIntentSender(file, context)
+    val intentSender =
+      if (FeatureFlags.ENABLE_GOPENPGP) {
+        GopenpgpAutofillDecryptActivity.makeDecryptFileIntentSender(file, context)
+      } else {
+        AutofillDecryptActivity.makeDecryptFileIntentSender(file, context)
+      }
     return makeIntentDataset(context, AutofillAction.Match, intentSender, metadata, imeSpec)
   }
 
diff --git a/app/src/main/java/dev/msfjarvis/aps/util/autofill/AutofillResponseBuilder.kt b/app/src/main/java/dev/msfjarvis/aps/util/autofill/AutofillResponseBuilder.kt
index 9dabf914..2f3568c4 100644
--- a/app/src/main/java/dev/msfjarvis/aps/util/autofill/AutofillResponseBuilder.kt
+++ b/app/src/main/java/dev/msfjarvis/aps/util/autofill/AutofillResponseBuilder.kt
@@ -25,6 +25,8 @@ import dev.msfjarvis.aps.ui.autofill.AutofillDecryptActivity
 import dev.msfjarvis.aps.ui.autofill.AutofillFilterView
 import dev.msfjarvis.aps.ui.autofill.AutofillPublisherChangedActivity
 import dev.msfjarvis.aps.ui.autofill.AutofillSaveActivity
+import dev.msfjarvis.aps.ui.autofill.GopenpgpAutofillDecryptActivity
+import dev.msfjarvis.aps.util.FeatureFlags
 import java.io.File
 
 @RequiresApi(Build.VERSION_CODES.O)
@@ -56,7 +58,12 @@ class AutofillResponseBuilder(form: FillableForm) {
   private fun makeMatchDataset(context: Context, file: File): Dataset? {
     if (!scenario.hasFieldsToFillOn(AutofillAction.Match)) return null
     val metadata = makeFillMatchMetadata(context, file)
-    val intentSender = AutofillDecryptActivity.makeDecryptFileIntentSender(file, context)
+    val intentSender =
+      if (FeatureFlags.ENABLE_GOPENPGP) {
+        GopenpgpAutofillDecryptActivity.makeDecryptFileIntentSender(file, context)
+      } else {
+        AutofillDecryptActivity.makeDecryptFileIntentSender(file, context)
+      }
     return makeIntentDataset(context, AutofillAction.Match, intentSender, metadata)
   }
 
diff --git a/crypto-common/api/crypto-common.api b/crypto-common/api/crypto-common.api
new file mode 100644
index 00000000..7493379c
--- /dev/null
+++ b/crypto-common/api/crypto-common.api
@@ -0,0 +1,6 @@
+public abstract interface class dev/msfjarvis/aps/data/crypto/CryptoHandler {
+	public abstract fun canHandle (Ljava/lang/String;)Z
+	public abstract fun decrypt (Ljava/lang/String;[B[B)[B
+	public abstract fun encrypt (Ljava/lang/String;[B)[B
+}
+
diff --git a/crypto-common/build.gradle.kts b/crypto-common/build.gradle.kts
new file mode 100644
index 00000000..c1f3eef8
--- /dev/null
+++ b/crypto-common/build.gradle.kts
@@ -0,0 +1,8 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+plugins {
+  kotlin("jvm")
+  `aps-plugin`
+}
diff --git a/crypto-common/src/main/kotlin/dev/msfjarvis/aps/data/crypto/CryptoHandler.kt b/crypto-common/src/main/kotlin/dev/msfjarvis/aps/data/crypto/CryptoHandler.kt
new file mode 100644
index 00000000..453613a4
--- /dev/null
+++ b/crypto-common/src/main/kotlin/dev/msfjarvis/aps/data/crypto/CryptoHandler.kt
@@ -0,0 +1,25 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+package dev.msfjarvis.aps.data.crypto
+
+/** Generic interface to implement cryptographic operations on top of. */
+public interface CryptoHandler {
+
+  /**
+   * Decrypt the given [ciphertext] using a [privateKey] and [passphrase], returning a [ByteArray]
+   * corresponding to the decrypted plaintext.
+   */
+  public fun decrypt(privateKey: String, passphrase: ByteArray, ciphertext: ByteArray): ByteArray
+
+  /**
+   * Encrypt the given [plaintext] to the provided [publicKey], returning the encrypted ciphertext
+   * as a [ByteArray]
+   */
+  public fun encrypt(publicKey: String, plaintext: ByteArray): ByteArray
+
+  /** Given a [fileName], return whether this instance can handle it. */
+  public fun canHandle(fileName: String): Boolean
+}
diff --git a/crypto-pgp/api/crypto-pgp.api b/crypto-pgp/api/crypto-pgp.api
new file mode 100644
index 00000000..2164360c
--- /dev/null
+++ b/crypto-pgp/api/crypto-pgp.api
@@ -0,0 +1,7 @@
+public final class dev/msfjarvis/aps/data/crypto/GopenpgpCryptoHandler : dev/msfjarvis/aps/data/crypto/CryptoHandler {
+	public fun <init> ()V
+	public fun canHandle (Ljava/lang/String;)Z
+	public fun decrypt (Ljava/lang/String;[B[B)[B
+	public fun encrypt (Ljava/lang/String;[B)[B
+}
+
diff --git a/crypto-pgp/build.gradle.kts b/crypto-pgp/build.gradle.kts
new file mode 100644
index 00000000..493062b6
--- /dev/null
+++ b/crypto-pgp/build.gradle.kts
@@ -0,0 +1,15 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+plugins {
+  id("com.android.library")
+  kotlin("android")
+  `aps-plugin`
+}
+
+dependencies {
+  api(projects.cryptoCommon)
+  implementation(libs.aps.gopenpgp)
+  implementation(libs.dagger.hilt.core)
+}
diff --git a/crypto-pgp/src/main/AndroidManifest.xml b/crypto-pgp/src/main/AndroidManifest.xml
new file mode 100644
index 00000000..f72b702d
--- /dev/null
+++ b/crypto-pgp/src/main/AndroidManifest.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+  ~ SPDX-License-Identifier: LGPL-3.0-only WITH LGPL-3.0-linking-exception
+  -->
+
+<manifest package="dev.msfjarvis.aps.cryptopgp"></manifest>
diff --git a/crypto-pgp/src/main/kotlin/dev/msfjarvis/aps/data/crypto/GopenpgpCryptoHandler.kt b/crypto-pgp/src/main/kotlin/dev/msfjarvis/aps/data/crypto/GopenpgpCryptoHandler.kt
new file mode 100644
index 00000000..5d14b160
--- /dev/null
+++ b/crypto-pgp/src/main/kotlin/dev/msfjarvis/aps/data/crypto/GopenpgpCryptoHandler.kt
@@ -0,0 +1,49 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+package dev.msfjarvis.aps.data.crypto
+
+import com.proton.Gopenpgp.crypto.Crypto
+import com.proton.Gopenpgp.helper.Helper
+import javax.inject.Inject
+
+/** Gopenpgp backed implementation of [CryptoHandler]. */
+public class GopenpgpCryptoHandler @Inject constructor() : CryptoHandler {
+
+  /**
+   * Decrypt the given [ciphertext] using the given PGP [privateKey] and corresponding [passphrase].
+   */
+  override fun decrypt(
+    privateKey: String,
+    passphrase: ByteArray,
+    ciphertext: ByteArray,
+  ): ByteArray {
+    // Decode the incoming cipher into a string and try to guess if it's armored.
+    val cipherString = ciphertext.decodeToString()
+    val isArmor = cipherString.startsWith("-----BEGIN PGP MESSAGE-----")
+    val message =
+      if (isArmor) {
+        Crypto.newPGPMessageFromArmored(cipherString)
+      } else {
+        Crypto.newPGPMessage(ciphertext)
+      }
+    return Helper.decryptBinaryMessageArmored(
+      privateKey,
+      passphrase,
+      message.armored,
+    )
+  }
+
+  override fun encrypt(publicKey: String, plaintext: ByteArray): ByteArray {
+    return Helper.encryptBinaryMessage(
+      publicKey,
+      plaintext,
+    )
+  }
+
+  override fun canHandle(fileName: String): Boolean {
+    return fileName.split('.').last() == "gpg"
+  }
+}
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index dca7c641..77ae2d0a 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -72,6 +72,7 @@ dagger-hilt-core = { module = "com.google.dagger:hilt-core", version.ref = "hilt
 android-desugarJdkLibs = "com.android.tools:desugar_jdk_libs:1.1.5"
 
 # First-party libraries
+aps-gopenpgp = "com.github.android-password-store:gopenpgp:0.1.5"
 aps-sublimeFuzzy = "com.github.android-password-store:sublime-fuzzy:1.0.0"
 aps-zxingAndroidEmbedded = "com.github.android-password-store:zxing-android-embedded:4.2.0"
 
diff --git a/settings.gradle.kts b/settings.gradle.kts
index 37ce4d98..bcb9fae4 100644
--- a/settings.gradle.kts
+++ b/settings.gradle.kts
@@ -8,6 +8,10 @@ include(":app")
 
 include(":autofill-parser")
 
+include(":crypto-common")
+
+include(":crypto-pgp")
+
 include(":format-common")
 
 include(":openpgp-ktx")