better error handling for bad encrypted data checksum

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

@@ -1037,6 +1037,7 @@
     <string name="msg_dc_clear_signature">"Saving signature data for later"</string>
     <string name="msg_dc_clear">"Processing cleartext data"</string>
     <string name="msg_dc_error_bad_passphrase">"Error unlocking key, bad password!"</string>
+    <string name="msg_dc_error_corrupt_data">"Data is corrupt!"</string>
     <string name="msg_dc_error_extract_key">"Unknown error unlocking key!"</string>
     <string name="msg_dc_error_integrity_check">"Integrity check error!"</string>
     <string name="msg_dc_error_integrity_missing">"Missing integrity check! This can happen because the encrypting application is out of date, or from a downgrade attack."</string>