SecSIPId Module

Daniel-Constantin Mierla

   asipto.com
   <miconda@gmail.com>

Edited by

Daniel-Constantin Mierla

   <miconda@gmail.com>

   Copyright © 2020 http://www.asipto.com
     __________________________________________________________________

   Table of Contents

   1. Admin Guide

        1. Overview
        2. Dependencies

              2.1. Kamailio Modules
              2.2. External Libraries or Applications

        3. Parameters

              3.1. expire (int)
              3.2. timeout (int)
              3.3. cache_dir (str)
              3.4. cache_expire (int)
              3.5. modproc (str)
              3.6. libopt (str)

        4. Functions

              4.1. secsipid_check_identity(keyPath)
              4.2. secsipid_check_identity(pubkeyVal)
              4.3. secsipid_get_url(url, ovar)
              4.4. secsipid_add_identity(origTN, destTN, attest, origID,
                      x5u, keyPath)

        5. Installation

   List of Examples

   1.1. Set expire parameter
   1.2. Set timeout parameter
   1.3. Set cache_dir parameter
   1.4. Set cache_expire parameter
   1.5. Set modproc parameter
   1.6. Set libopt parameter
   1.7. secsipid_check_identity usage
   1.8. secsipid_check_identity_pubkey usage
   1.9. secsipid_get_url usage
   1.10. secsipid_add_identity usage
   1.11. Libsecsipid Usage

Chapter 1. Admin Guide

   Table of Contents

   1. Overview
   2. Dependencies

        2.1. Kamailio Modules
        2.2. External Libraries or Applications

   3. Parameters

        3.1. expire (int)
        3.2. timeout (int)
        3.3. cache_dir (str)
        3.4. cache_expire (int)
        3.5. modproc (str)
        3.6. libopt (str)

   4. Functions

        4.1. secsipid_check_identity(keyPath)
        4.2. secsipid_check_identity(pubkeyVal)
        4.3. secsipid_get_url(url, ovar)
        4.4. secsipid_add_identity(origTN, destTN, attest, origID, x5u,
                keyPath)

   5. Installation

1. Overview

   The module implements secure SIP identity specifications - STIR (Secure
   Telephony Identity Revisited) and SHAKEN (Signature-based Handling of
   Asserted information using toKENs) IETF extensions for SIP (RFC8224,
   RFC8588).

   It exports the functions to check and generate SIP Identity header.

   Note that this module needs "secsipid_proc.so" module to be installed,
   but without loading the "secsipid_proc.so" via "loadmodule". This
   module loads "secsipid_proc.so" in child init callback in order to
   initialize the "libsecsipid" per child process.

2. Dependencies

   2.1. Kamailio Modules
   2.2. External Libraries or Applications

2.1. Kamailio Modules

   The following modules must be installed (but not loaded) to use this
   module:
     * secsipid_proc.

2.2. External Libraries or Applications

   The following libraries or applications must be installed before
   running Kamailio with this module loaded:
     * none.

3. Parameters

   3.1. expire (int)
   3.2. timeout (int)
   3.3. cache_dir (str)
   3.4. cache_expire (int)
   3.5. modproc (str)
   3.6. libopt (str)

3.1. expire (int)

   The interval in seconds after which the Identity header JWT is
   considered to be expired.

   Default value is 300.

   Example 1.1. Set expire parameter
...
modparam("secsipid", "expire", 600)
...

3.2. timeout (int)

   The interval in seconds after which the HTTP GET operation to download
   the public key times out.

   Default value is 5.

   Example 1.2. Set timeout parameter
...
modparam("secsipid", "timeout", 2)
...

3.3. cache_dir (str)

   The path to the directory where to save cached pyblic keys. If set, it
   activates the public key file caching in the libsecsipid library.

   Default value is "".

   Example 1.3. Set cache_dir parameter
...
modparam("secsipid", "cache_dir", "/tmp/kamailio/secsipid")
...

3.4. cache_expire (int)

   The interval in seconds after which a cached public key is considered
   expired. This value is passed to the libsecsipid library.

   Default value is 3600.

   Example 1.4. Set cache_expire parameter
...
modparam("secsipid", "cache_expire", 7200)
...

3.5. modproc (str)

   The name of or the path to the required per-process API module.

   Default value is "secsipid_proc.so".

   Example 1.5. Set modproc parameter
...
modparam("secsipid", "modproc", "secsipid_proc2.so")
...

3.6. libopt (str)

   Set a libsecsipid option. The value has to be name=value. The parameter
   can be set many times.

   Default value is "" (not set).

   Example 1.6. Set libopt parameter
...
modparam("secsipid", "libopt", "CacheExpires=0")
...

4. Functions

   4.1. secsipid_check_identity(keyPath)
   4.2. secsipid_check_identity(pubkeyVal)
   4.3. secsipid_get_url(url, ovar)
   4.4. secsipid_add_identity(origTN, destTN, attest, origID, x5u,
          keyPath)

4.1.  secsipid_check_identity(keyPath)

   Check the validity of the Identity header using the keys stored in the
   file specified by "keyPath". If the parameter is empty, the function is
   downloading the key using the URL from "info" parameter of the Identity
   header, using the value od "timeout" parameter to limit the download
   time. The validity of the JWT body in the Identity header is also
   checked against the "expire" parameter.

   The parameters can contain pseudo-variables.

   This function can be used from ANY_ROUTE.

   Example 1.7. secsipid_check_identity usage
...
request_route {
    ...
        if(secsipid_check_identity("/secsipid/$si/cert.pem")) { ... }
    ...
        if(secsipid_check_identity("")) { ... }
    ...
}
...

   Further checks can be done with config operations, decoding the JWT
   header and payload using {s.select} and {s.decode.base64t}
   transformations together with jansson module.

4.2.  secsipid_check_identity(pubkeyVal)

   Similar to secsipid_check_identity() with the public key value provided
   in the parameter.

   The parameters can contain pseudo-variables.

   This function can be used from ANY_ROUTE.

   Example 1.8. secsipid_check_identity_pubkey usage
...
request_route {
  ...
  http_client_query("https://provider.com/stir-shaken/cert.pem", "$var(pubkey)")
;
  ...
  if(secsipid_check_identity_pubkey("$var(pubkey)")) { ... }
  ...
}
...

4.3.  secsipid_get_url(url, ovar)

   Get the content of a URL and store the result in a variable.

   The url parameters can contain pseudo-variables and ovar has to be the
   name of a writtable pseudo-variable.

   This function can be used from ANY_ROUTE.

   Example 1.9. secsipid_get_url usage
...
request_route {
  ...
  if(secsipid_get_url("https://$fd/stirshaken/cert.pem", "$var(pubkey)")) { ...
}
  ...
}
...

4.4.  secsipid_add_identity(origTN, destTN, attest, origID, x5u, keyPath)

   Add Identity header using the key specified by "keyPath" to sign the
   JWT body. If origID is empty, a UUID string is generated to fill the
   field. The origTN represents the origination telephone number; destTN
   represents the destination telephone number; x5u is the HTTP URL
   referencing to the public key that should be used to verify the
   signature; attest represents the attestation level (should be "A", "B"
   or "C").

   The parameters can contain pseudo-variables.

   This function can be used from ANY_ROUTE.

   Example 1.10. secsipid_add_identity usage
...
request_route {
    ...
    secsipid_add_identity("$fU", "$rU", "A", "",
        "https://kamailio.org/stir/$rd/cert.pem", "/secsipid/$rd/key.pem");
    ...
}
...

5. Installation

   The module needs "secsipdi_proc.so" module thatdepends on
   "libsecsipid", which is a component of "sipsecidx" project from
   https://github.com/asipto/secsipidx/. The library is implemented in Go
   language, with generated C API and library. Until the libsecsipid is
   going to be packaged in OS distributions, the secsipid_proc module can
   be compiled by copying secsipid.h libsecsipid.h and libsecsipid.a files
   in the folder of the module.

   To generate the libsecsipid.a file, it requires to have Go language
   installed and its environment configured, then run the following
   commands:

   Example 1.11. Libsecsipid Usage
...
go get https://github.com/asipto/secsipidx
cd $GOPATH/src/github.com/asipto/secsipidx/csecsipid/
make liba
cp secsipid.h libsecsipid.h libsecsipid.a \
    /path/to/kamailio/src/modules/secsipid_proc/

cd /path/to/kamailio/
make include_modules="secsipid secsipid_proc ..." cfg
make all
make install

## or compiling individual modules for use inside source tree
# make modules modules=src/modules/secsipid_proc
# make modules modules=src/modules/secsipid
...