challenger

OAuth 2.0-based authentication service that validates user can receive messages at a certain address
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README (3591B)

      1 About CHALLENGER
      2 ----------------
      3 
      4 
      5 Challenger implements an HTTP server that allows clients to validate
      6 that a user is able to receive TAN codes at a given address using
      7 OAuth 2.0-style authorization.
      8 
      9 Envisioned use-cases are KYC checks where a user must prove that they
     10 are able to receive SMS, e-mails or physical mail.
     11 
     12 
     13 Accountability:
     14 ===============
     15 
     16 Clients must be registered before they can use the service. To
     17 initiate an address verification, clients must first setup an
     18 authorization session before directing the user agent towards the
     19 ``/login`` endpoint.  The system automatically tracks how many address
     20 verification session a particular client has authorized.  This is
     21 expected to be useful in cases where address verifications have
     22 non-negligible cost.  The system also limits how often a user-agent
     23 may change the address per authorization session as well as the number
     24 of times the TAN code is transmitted to each address. Finally, it
     25 of course also limits the number of times a user may enter a TAN
     26 code.
     27 
     28 
     29 Time limits:
     30 ============
     31 
     32 Once authorized, a client has limited time to use the user agent's
     33 authorization code.  The resulting grant also has limited lifetime
     34 during which the client must download the verified address of the
     35 user.
     36 
     37 
     38 Flexibility:
     39 ============
     40 
     41 The actual transmission of the TAN code is done via a separate
     42 program that is simply invoked by the challenger service. This makes
     43 the code useful for all types of address validations.  Simple shell
     44 scripts are provided for SMS, e-mail and physical address validation.
     45 
     46 All user-facing forms are fully customizable and provided as Mustach
     47 templates.  By changing the templates, the look-and-feel of the
     48 service can be freely adapted.
     49 
     50 
     51 Usability:
     52 ==========
     53 
     54 Challenger uses a simple REST-based API documented at
     55 https://docs.taler.net/.  The authorization flow is believed
     56 to be fully compatible with OAuth 2.0.
     57 
     58 
     59 Limitations:
     60 ============
     61 
     62 Challenger does at this time not include HTTPS support. While this could
     63 be trivially added, we expect Challenger to be run behind a reverse proxy
     64 that terminates TLS.
     65 
     66 At this time, Challenger only works with a Postgres database. Other database
     67 backends could easily be written in the future.
     68 
     69 
     70 Installation
     71 ============
     72 
     73 See INSTALL for generic installation instructions.  In addition,
     74 Challenger requires GNUnet, GNU Taler Exchange, and GNU Taler Merchant
     75 libraries.  If these are installed in a non-standard place, use the
     76 configure script options --with-gnunet=DIR, --with-exchange=DIR, and
     77 --with-merchant=DIR, respectively.
     78 
     79 The following are likewise required:
     80 
     81   libmicrohttpd --with-microhttpd=DIR
     82   PostgreSQL    --with-postgresql=PATH-TO-PG-CONFIG
     83 
     84 Other non-essential dependencies are indicated by --with-FOO
     85 in the "./configure --help" output.
     86 
     87 
     88 
     89 Dependencies:
     90 =============
     91 
     92 Build tools for compiling Challenger from source:
     93 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     94 
     95 - gcc or clang
     96 - autoconf           >= 2.69        (building from git)
     97 - automake           >= 1.11.1      (building from git)
     98 - recutils           >= 1.0         (building from git)
     99 - libtool            >= 2.2
    100 - makeinfo           >= 4.8
    101 - make[*3]
    102 - pkgconf or pkg-config
    103 - sphinx
    104 - sphinx-rtd-theme
    105 - sphinx-multiversion
    106 
    107 
    108 Direct dependencies
    109 ~~~~~~~~~~~~~~~~~~~
    110 
    111 These are the direct dependencies for running Challenger:
    112 
    113 - GNU Taler exchange >= 0.14.0
    114 - PostgreSQL         >= 15.0
    115 
    116 
    117 License:
    118 ========
    119 
    120 Challenger is released under the Affero GPL v3 or later.
    121 
    122 The primary source code is maintained at
    123 https://git.taler.net/challenger.git by the GNU Taler team.