1 files changed, 38 insertions, 0 deletions
diff --git a/app/src/main/java/dev/msfjarvis/aps/util/crypto/GpgIdentifier.kt b/app/src/main/java/dev/msfjarvis/aps/util/crypto/GpgIdentifier.kt
new file mode 100644
index 00000000..51b3b76b
--- /dev/null
+++ b/app/src/main/java/dev/msfjarvis/aps/util/crypto/GpgIdentifier.kt
@@ -0,0 +1,38 @@
+package dev.msfjarvis.aps.util.crypto
+
+import me.msfjarvis.openpgpktx.util.OpenPgpUtils
+
+sealed class GpgIdentifier {
+    data class KeyId(val id: Long) : GpgIdentifier()
+    data class UserId(val email: String) : GpgIdentifier()
+
+    companion object {
+        @OptIn(ExperimentalUnsignedTypes::class)
+        fun fromString(identifier: String): GpgIdentifier? {
+            if (identifier.isEmpty()) return null
+            // Match long key IDs:
+            // FF22334455667788 or 0xFF22334455667788
+            val maybeLongKeyId = identifier.removePrefix("0x").takeIf {
+                it.matches("[a-fA-F0-9]{16}".toRegex())
+            }
+            if (maybeLongKeyId != null) {
+                val keyId = maybeLongKeyId.toULong(16)
+                return KeyId(keyId.toLong())
+            }
+
+            // Match fingerprints:
+            // FF223344556677889900112233445566778899 or 0xFF223344556677889900112233445566778899
+            val maybeFingerprint = identifier.removePrefix("0x").takeIf {
+                it.matches("[a-fA-F0-9]{40}".toRegex())
+            }
+            if (maybeFingerprint != null) {
+                // Truncating to the long key ID is not a security issue since OpenKeychain only accepts
+                // non-ambiguous key IDs.
+                val keyId = maybeFingerprint.takeLast(16).toULong(16)
+                return KeyId(keyId.toLong())
+            }
+
+            return OpenPgpUtils.splitUserId(identifier).email?.let { UserId(it) }
+        }
+    }
+}