feat(pgpainless): add detection for passphrase-less messages (#3069)

* WIP: feat(pgpainless): add detection for passphrase-less messages

* refactor: test keys instead of the message

This makes more logical sense

3 files changed, 36 insertions, 0 deletions

diff --git a/crypto/common/src/main/kotlin/app/passwordstore/crypto/CryptoHandler.kt b/crypto/common/src/main/kotlin/app/passwordstore/crypto/CryptoHandler.kt
index 898cf058..c823342b 100644
--- a/crypto/common/src/main/kotlin/app/passwordstore/crypto/CryptoHandler.kt
+++ b/crypto/common/src/main/kotlin/app/passwordstore/crypto/CryptoHandler.kt
@@ -41,4 +41,9 @@ public interface CryptoHandler<Key, EncOpts : CryptoOptions, DecryptOpts : Crypt
 
   /** Given a [fileName], return whether this instance can handle it. */
   public fun canHandle(fileName: String): Boolean
+
+  /**
+   * Inspects the given [keys] and returns `false` if none of them require a passphrase to decrypt.
+   */
+  public fun isPassphraseProtected(keys: List<Key>): Boolean
 }
diff --git a/crypto/pgpainless/src/main/kotlin/app/passwordstore/crypto/PGPainlessCryptoHandler.kt b/crypto/pgpainless/src/main/kotlin/app/passwordstore/crypto/PGPainlessCryptoHandler.kt
index 1aabe54f..b3f2a64b 100644
--- a/crypto/pgpainless/src/main/kotlin/app/passwordstore/crypto/PGPainlessCryptoHandler.kt
+++ b/crypto/pgpainless/src/main/kotlin/app/passwordstore/crypto/PGPainlessCryptoHandler.kt
@@ -11,6 +11,7 @@ import app.passwordstore.crypto.errors.NoKeysProvidedException
 import app.passwordstore.crypto.errors.NonStandardAEAD
 import app.passwordstore.crypto.errors.UnknownError
 import com.github.michaelbull.result.Result
+import com.github.michaelbull.result.mapBoth
 import com.github.michaelbull.result.mapError
 import com.github.michaelbull.result.runCatching
 import java.io.InputStream
@@ -140,4 +141,14 @@ public class PGPainlessCryptoHandler @Inject constructor() :
   public override fun canHandle(fileName: String): Boolean {
     return fileName.substringAfterLast('.', "") == "gpg"
   }
+
+  public override fun isPassphraseProtected(keys: List<PGPKey>): Boolean =
+    keys
+      .mapNotNull { key -> PGPainless.readKeyRing().secretKeyRing(key.contents) }
+      .map(::keyringHasPassphrase)
+      .all { it }
+
+  internal fun keyringHasPassphrase(keyRing: PGPSecretKeyRing) =
+    runCatching { keyRing.secretKey.extractPrivateKey(null) }
+      .mapBoth(success = { false }, failure = { true })
 }
diff --git a/crypto/pgpainless/src/test/kotlin/app/passwordstore/crypto/PGPainlessCryptoHandlerTest.kt b/crypto/pgpainless/src/test/kotlin/app/passwordstore/crypto/PGPainlessCryptoHandlerTest.kt
index 5de2bf4f..600cc39d 100644
--- a/crypto/pgpainless/src/test/kotlin/app/passwordstore/crypto/PGPainlessCryptoHandlerTest.kt
+++ b/crypto/pgpainless/src/test/kotlin/app/passwordstore/crypto/PGPainlessCryptoHandlerTest.kt
@@ -156,6 +156,26 @@ class PGPainlessCryptoHandlerTest {
   }
 
   @Test
+  fun detectsKeysWithPassphrase() {
+    assertTrue(cryptoHandler.isPassphraseProtected(listOf(PGPKey(TestUtils.getArmoredSecretKey()))))
+    assertTrue(
+      cryptoHandler.isPassphraseProtected(
+        listOf(PGPKey(TestUtils.getArmoredSecretKeyWithMultipleIdentities()))
+      )
+    )
+  }
+
+  @Test
+  fun detectsKeysWithoutPassphrase() {
+    // Uses the internal method instead of the public API because GnuPG seems to have made it
+    // impossible to generate a key without a passphrase and I can't care to find a magical
+    // incantation to convince it I am smarter than whatever they are protecting against.
+    assertFalse(
+      cryptoHandler.keyringHasPassphrase(PGPainless.generateKeyRing().modernKeyRing("John Doe"))
+    )
+  }
+
+  @Test
   fun canHandleFiltersFormats() {
     assertFalse { cryptoHandler.canHandle("example.com") }
     assertTrue { cryptoHandler.canHandle("example.com.gpg") }