Introduction to the YubiKey PIV Application
===========================================

The YubiKey supports the Personal Identity Verification (PIV) card
interface specified in NIST SP 800-73 document "Cryptographic
Algorithms and Key Sizes for PIV".  This enables you to perform RSA or
ECC sign/decrypt operations using a private key stored on the
smartcard, through common interfaces like PKCS#11.

* PIV Standards http://csrc.nist.gov/groups/SNS/piv/standards.html

General information
-------------------

The default PIN code is 123456.  The default PUK code is 12345678.

The default 3DES management key (9B) is
010203040506070801020304050607080102030405060708.

The following key slots exists:

* 9A, 9C, 9D, 9E: RSA 1024, RSA 2048, or ECC secp256r1 keys
  (algorithms 6, 7, 11 respectively).

* 9B: Triple-DES key (algorithm 3) for PIV management.

The maximum size of stored objects is 2005 bytes.

Currently all functionality are available over both contact and
contactless interfaces (contrary to what the specifications mandate).

Preparing a for real use
------------------------

You would typically change the management key to make sure nobody but
you can modify the state of the PIV application on the.  Make sure to
keep a copy of the key around for later use.

  key=`dd if=/dev/random bs=1 count=24 2>/dev/null | hexdump -v -e '/1 "%02X"'`
  echo $key
  yubico-piv-tool -a set-mgm-key -n $key

The PIN and PUK should be changed as well.

  pin=`dd if=/dev/random bs=1 count=6 2>/dev/null | hexdump -v -e '/1 "%u"'|cut -c1-6`
  echo $pin

  puk=`dd if=/dev/random bs=1 count=6 2>/dev/null | hexdump -v -e '/1 "%u"'|cut -c1-8`
  echo $puk

  yubico-piv-tool -a change-pin -P 123456 -N $pin
  yubico-piv-tool -a change-puk -P 12345678 -N $puk

Other useful commands
---------------------

To generate a new private key:

  yubico-piv-tool -k $key -a generate -s 9c

To reset PIN/PUK retry counter AND codes (default pin 123456 puk
12345678):

  yubico-piv-tool -k $key -a verify -P $pin -a pin-retries --pin-retries 3 --puk-retries 3

To reset the application (PIN/PUK need to be blocked hence trying a couple
of times -- you need to modify this if you have changed the default
number of PIN/PUK retries).

  yubico-piv-tool -a verify-pin -P 471112
  yubico-piv-tool -a verify-pin -P 471112
  yubico-piv-tool -a verify-pin -P 471112
  yubico-piv-tool -a verify-pin -P 471112
  yubico-piv-tool -a change-puk -P 471112 -N 6756789
  yubico-piv-tool -a change-puk -P 471112 -N 6756789
  yubico-piv-tool -a change-puk -P 471112 -N 6756789
  yubico-piv-tool -a change-puk -P 471112 -N 6756789
  yubico-piv-tool -a reset

Software
--------

Card management has been tested with the tools from the OpenSC
project, specifically piv-tool, and Yubico's PIV software (see
below).  Basic features should work with any PIV compliant 
middleware.

* https://github.com/OpenSC/OpenSC/wiki
* https://developers.yubico.com/yubico-piv-tool/
* https://developers.yubico.com/yubikey-piv-manager/
* https://github.com/OpenSC/OpenSC/wiki/US-PIV
* https://github.com/OpenSC/OpenSC/wiki/PivTool

Card Holder Unique Identifier
-----------------------------

For the application to be usable in windows the object CHUID (Card Holder
Unique Identifier) has to be set and unique. The card contents are
also aggressively cached so the CHUID has to be changed if the card
contents change.