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-# blue-app-openpgp-card
-OpenPGP Card Application 
+## GnuPG application: blue-app-gnupg
+
+GnuPG application for Ledger Blue and Nano S
+
+This application implements "The OpenPGP card" specification revision 3.0. This specification is available in *doc* directory and at:
+ttps://g10code.com/p-card.html
+
+The application supports:
+  - RSA with key up to 4096 bits 
+  - ECDSA with secp256k1, secp256r1, brainpool 256r1 and brainpool 256t1 curves
+  - EDDSA with Ed25519 curve 
+  - ECDH with  secp256k1, secp256r1, brainpool 256r1, brainpool 256t1 and curve25519 curves
+
+To compile it, use at least the Nano S SDK 1.3.1.3 on firmware 1.3.1
+
+This release is in beta stage with known missing parts (see also Add-on) :
+
+   * Ledger Blue support
+   * Seed mode ON/OFF via apdu
+
+
+## Add-on
+
+The GnuPG application implements the following addon:
+  - serial moddification
+  - on screen reset
+  - 3 independent key slots
+  - seeded key generation
+
+Technical specification is available in doc/gpgcard3.0-addon.rst
+
+   
+### Key slot
+
+"The OpenPGP card" specification specifies:
+  - 3 asymmetric keys : Signature, Decryption, Authentication
+  - 1 symmetric key
+
+The blue application allow you to store 3 different key sets, named slot. Each slot contains the above 4 keys.
+You can choose the active slot on the main screen.
+When installed the default slot is "1". You can change it in settings.
+
+   
+### seeded key generation
+
+A seeded mode is implemented in order to restore private keys on a new token.
+In this mode key material is generated from the global token seeded.
+
+More details to come... 
+
+### On screen reset
+
+The application can be reset as if it was fresh installed. In settings, choose reset and confirm.
+