module iana-crypt-hash {

  namespace "urn:ietf:params:xml:ns:yang:iana-crypt-hash";

  prefix ianach;

  organization "IANA";

  contact

    "        Internet Assigned Numbers Authority

     Postal: ICANN

             12025 Waterfront Drive, Suite 300

             Los Angeles, CA  90094-2536

             United States

     Tel:    +1 310 301 5800

     E-Mail: iana@iana.org>";

  description

    "This YANG module defines a type for storing passwords

     using a hash function and features to indicate which hash

     functions are supported by an implementation.

     The latest revision of this YANG module can be obtained from

     the IANA web site.

     Requests for new values should be made to IANA via

     email (iana@iana.org).

     Copyright (c) 2014 IETF Trust and the persons identified as

     authors of the code.  All rights reserved.

     Redistribution and use in source and binary forms, with or

     without modification, is permitted pursuant to, and subject

     to the license terms contained in, the Simplified BSD License

     set forth in Section 4.c of the IETF Trust's Legal Provisions

     Relating to IETF Documents

     (http://trustee.ietf.org/license-info).

     The initial version of this YANG module is part of RFC 7317;

     see the RFC itself for full legal notices.";

  revision 2014-08-06 {

    description

      "Initial revision.";

    reference

      "RFC 7317: A YANG Data Model for System Management";

  }

  typedef crypt-hash {

    type string {

      pattern

        '$0$.*'

      + '|$1$[a-zA-Z0-9./]{1,8}$[a-zA-Z0-9./]{22}'

      + '|$5$(rounds=\d+$)?[a-zA-Z0-9./]{1,16}$[a-zA-Z0-9./]{43}'

      + '|$6$(rounds=\d+$)?[a-zA-Z0-9./]{1,16}$[a-zA-Z0-9./]{86}';

    }

    description

      "The crypt-hash type is used to store passwords using

       a hash function.  The algorithms for applying the hash

       function and encoding the result are implemented in

       various UNIX systems as the function crypt(3).

       A value of this type matches one of the forms:

         $0$<clear text password>

         $<id>$<salt>$<password hash>

         $<id>$<parameter>$<salt>$<password hash>

       The '$0$' prefix signals that the value is clear text.  When

       such a value is received by the server, a hash value is

       calculated, and the string '$<id>$<salt>$' or

       $<id>$<parameter>$<salt>$ is prepended to the result.  This

       value is stored in the configuration data store.

       If a value starting with '$<id>$', where <id> is not '0', is

       received, the server knows that the value already represents a

       hashed value and stores it 'as is' in the data store.

       When a server needs to verify a password given by a user, it

       finds the stored password hash string for that user, extracts

       the salt, and calculates the hash with the salt and given

       password as input.  If the calculated hash value is the same

       as the stored value, the password given by the client is

       accepted.

       This type defines the following hash functions:

         id | hash function | feature

         ---+---------------+-------------------

          1 | MD5           | crypt-hash-md5

          5 | SHA-256       | crypt-hash-sha-256

          6 | SHA-512       | crypt-hash-sha-512

       The server indicates support for the different hash functions

       by advertising the corresponding feature.";

    reference

      "IEEE Std 1003.1-2008 - crypt() function

       RFC 1321: The MD5 Message-Digest Algorithm

       FIPS.180-4.2012: Secure Hash Standard (SHS)";

  }

  feature crypt-hash-md5 {

    description

      "Indicates that the device supports the MD5

       hash function in 'crypt-hash' values.";

    reference "RFC 1321: The MD5 Message-Digest Algorithm";

  }

  feature crypt-hash-sha-256 {

    description

      "Indicates that the device supports the SHA-256

       hash function in 'crypt-hash' values.";

    reference "FIPS.180-4.2012: Secure Hash Standard (SHS)";

  }

  feature crypt-hash-sha-512 {

    description

      "Indicates that the device supports the SHA-512

       hash function in 'crypt-hash' values.";

    reference "FIPS.180-4.2012: Secure Hash Standard (SHS)";

  }

}