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

2 files changed, 55 insertions, 0 deletions

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"
+  }
+}