<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE erlref SYSTEM "erlref.dtd">

<erlref>
  <header>
    <copyright>
      <year>2012</year>
      <year>2021</year>
      <holder>Ericsson AB, All Rights Reserved</holder>
    </copyright>
    <legalnotice>
      Licensed under the Apache License, Version 2.0 (the "License");
      you may not use this file except in compliance with the License.
      You may obtain a copy of the License at
 
          http://www.apache.org/licenses/LICENSE-2.0

      Unless required by applicable law or agreed to in writing, software
      distributed under the License is distributed on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      See the License for the specific language governing permissions and
      limitations under the License.

      The Initial Developer of the Original Code is Ericsson AB.
    </legalnotice>
    <title>ssh_server_key_api</title>
    <prepared></prepared>
    <docno></docno>
    <date></date>
    <rev></rev>
  </header>
  <module since="OTP R16B">ssh_server_key_api</module>
  <modulesummary>
    -behaviour(ssh_server_key_api).
  </modulesummary>
  <description>
    <p>Behaviour describing the API for public key handling of an SSH server. By implementing
    the callbacks defined in this behavior, the public key handling of an SSH server can
    be customized. By default the SSH application implements this behavior
    with help of the standard OpenSSH files,
    see the <seeapp marker="SSH_app"> ssh(6)</seeapp> application manual.</p>
  </description>

  <!-- section>
    <title>DATA TYPES</title>

    <p>Type definitions that are used more than once in this module,
    or abstractions to indicate the intended use of the data
    type, or both. For more details on public key data types,
    refer to Section 2 Public Key Records in the
    <seeguide marker="public_key:public_key_records"> public_key user's guide</seeguide>.
    </p>

    <taglist>
      <tag><c>boolean() =</c></tag>
      <item><p><c>true | false</c></p></item>
      <tag><c>string() =</c></tag>
      <item><p><c>[byte()]</c></p></item>
      <tag><c>public_key() =</c></tag>
      <item><p><c>#'RSAPublicKey'{} 
      | {integer(),#'Dss-Parms'{}} 
      | {#'ECPoint'{},{namedCurve,Curve::string()}}</c></p></item>
      <tag><c>private_key() =</c></tag>
      <item><p><c>#'RSAPrivateKey'{} 
      | #'DSAPrivateKey'{} 
      | #'ECPrivateKey'{}</c></p></item>      
      <tag><c>public_key_algorithm() =</c></tag>
      <item><p><c>'ssh-rsa' | 'ssh-dss' 
      | 'rsa-sha2-256' | 'rsa-sha2-384' | 'rsa-sha2-512'
      | 'ecdsa-sha2-nistp256' | 'ecdsa-sha2-nistp384' | 'ecdsa-sha2-nistp521' </c></p></item>
    </taglist>
  </section -->
  
  <datatypes>
    <datatype>
      <name name="daemon_key_cb_options"/>
      <desc>
	<p>Options provided to <seemfa marker="ssh#daemon/2">ssh:daemon/2,3</seemfa>.
	</p>
	<p>The option list given in the
	<seetype marker="ssh#key_cb_common_option"><c>key_cb</c></seetype>
	option is available with the key <c>key_cb_private</c>.
	</p>
      </desc>
    </datatype>
  </datatypes>

  <funcs>
    <func>
      <name since="OTP R16B">Module:host_key(Algorithm, DaemonOptions) ->
      {ok, PrivateKey} | {error, Reason}</name>
      <fsummary>Fetches the host’s private key.</fsummary>
      <type>
	<v>Algorithm = <seetype marker="ssh#pubkey_alg">ssh:pubkey_alg()</seetype></v>
	<d>Host key algorithm.</d>

	<v>DaemonOptions =  <seetype marker="#daemon_key_cb_options">daemon_key_cb_options()</seetype></v>

	<v>PrivateKey = <seetype marker="public_key:public_key#private_key">public_key:private_key()</seetype>
	   | <seetype marker="crypto:crypto#engine_key_ref">crypto:engine_key_ref()</seetype>
	</v>

	<d>Private key of the host matching the <c>Algorithm</c>.
	It may be a reference to a 'ssh-rsa', rsa-sha2-* or 'ssh-dss' (NOT ecdsa) key stored in a loaded Engine.</d>

	<v>Reason = term()</v>
      </type>
      <desc>
	  <p>Fetches the private key of the host.</p>
      </desc>
    </func>

    <func>
      <name since="OTP R16B">Module:is_auth_key(PublicUserKey, User, DaemonOptions) -> Result</name>
      <fsummary>Checks if the user key is authorized.</fsummary>
      <type>
	<v>PublicUserKey = <seetype marker="public_key:public_key#public_key">public_key:public_key()</seetype></v>
	<d>Normally an RSA, DSA or ECDSA public key, but handling of other public keys can be added</d>

	<v>User = string()</v>
	<d>User owning the public key.</d>

	<v>DaemonOptions =  <seetype marker="#daemon_key_cb_options">daemon_key_cb_options()</seetype></v>

	<v>Result = boolean()</v>
      </type>
      <desc>
	 <p>Checks if the user key is authorized.</p>
      </desc>
    </func>

  </funcs>

</erlref>
