Created Alternative Passphrase Methods (markdown)

Alternative-Passphrase-Methods.md

@@ -0,0 +1,18 @@
+* New subpacket
+As a general mechanism, we can add a non-exportable direct key signature to any keyring which carries a "hint" to the key's passphrase in one of its subpackets. This way, we can store auxiliary semantics about a passphrase while retaining the design principle that all information stored in the database is contained entirely in the keyring blobs.
+Exemplary types of such auxiliary information could be flags that the passphrase should be entered as a pin, lock pattern, or obtained via nfc.
+
+### NFC
+
+### Lockpattern
+
+### PIN
+
+## Export
+As on private key export for a new extra long passphrase to protect against offline attacks!
+
+## Attack model
+| Attack                      | Passphrase | NFC | PIN | Lockpattern |
+| Offline brute force attacks | yes |        yes | no  | no |
+| Lend smartphone to other guy | | | | |
+| Shoulder surfing            | no | yes | | |