txrestserver 1.0.0

A simple REST server for twisted-python with access authentication support

txrestserver

A twisted-python REST server that supports authentication. The server can also serve page and form resources, but the primary focus is a flexible and minimal implementation for REST services.

As authentication features, examples, and unit tests are added, the public interfaces to this module are subject to change. The design goal is to provide a small set of simple classes that can easily be configured for various access authentication mechanisms and for credentials/secrets storage.

Status:

Release History

Version	Notes
1.0.0	Upgrade module versions and target first release to be for Python 3.8 -> 3.10
0.4.0	Digest Authentication Supported. Only plain text dictionary checker tested at this time.
	Unit test coverage of basic-auth/plaintext authentication, verification of
	UnixPasswordChecker (docker image) - this version is not yet released
0.3.1	Bugfix to type in the init methods for the basic and digest access classes
0.3.0	Began initial separation of API from Realm/Checkers with some initial checker types defined
0.2.0	Reworked basic server API and added unit/security test coverage
0.1.0	Initial pre-release (Alpha) with basic access authentication Support

Authentication Support

Currently both Basic and Digest access authentication is supported at this time with work on TLS-SRP authentication planned for the next release.

Note: Authentication descriptions below are from Wikipedia.

Basic Authentication

In the context of an HTTP transaction, basic access authentication is a method for an HTTP user agent (e.g. a web browser) to provide a user name and password when making a request. In basic HTTP authentication, a request contains a header field in the form of Authorization: Basic , where credentials is the Base64 encoding of ID and password joined by a single colon :.

Digest Authentication

Digest access authentication is one of the agreed-upon methods a web server can use to negotiate credentials, such as username or password, with a user's web browser. This can be used to confirm the identity of a user before sending sensitive information, such as online banking transaction history. It applies a hash function to the username and password before sending them over the network. In contrast, basic access authentication uses the easily reversible Base64 encoding instead of hashing, making it non-secure unless used in conjunction with TLS.

Technically, digest authentication is an application of MD5 cryptographic hashing with usage of nonce values to prevent replay attacks. It uses the HTTP protocol.

JSON Web Token

JSON Web Token is an Internet standard for creating data with optional signature and/or optional encryption whose payload holds JSON that asserts some number of claims. The tokens are signed either using a private secret or a public/private key. For example, a server could generate a token that has the claim "logged in as admin" and provide that to a client. The client could then use that token to prove that it is logged in as admin. The tokens can be signed by one party's private key (usually the server's) so that party can subsequently verify the token is legitimate. If the other party, by some suitable and trustworthy means, is in possession of the corresponding public key, they too are able to verify the token's legitimacy. The tokens are designed to be compact, URL-safe, and usable especially in a web-browser single-sign-on (SSO) context. JWT claims can typically be used to pass identity of authenticated users between an identity provider and a service provider, or any other type of claims as required by business processes.

JWT relies on other JSON-based standards: JSON Web Signature and JSON Web Encryption.

TLS-SRP

Transport Layer Security Secure Remote Password (TLS-SRP) ciphersuites are a set of cryptographic protocols that provide secure communication based on passwords, using an SRP password-authenticated key exchange.

There are two classes of TLS-SRP ciphersuites: The first class of cipher suites uses only SRP authentication. The second class uses SRP authentication and public key certificates together for added security.

Usually, TLS uses only public key certificates for authentication. TLS-SRP uses a value derived from a password (the SRP verifier) and a salt, shared in advance among the communicating parties, to establish a TLS connection. There are several possible reasons one may choose to use TLS-SRP:

Using password-based authentication does not require reliance on certificate authorities.

• The end user does not need to check the URL being certified. If the server does not know data derived from the password then the connection simply cannot be made. This prevents Phishing.

• Password authentication is less prone than certificate authentication to certain types of configuration mistakes, such as expired certificates or mismatched common name fields.

• TLS-SRP provides mutual authentication (the client and server both authenticate each other), while TLS with server certificates only authenticates the server to the client. Client certificates can authenticate the client to the server, but it may be easier for a user to remember a password than to install a certificate.

Examples

Examples are available on Github

Acknowledgements

Thanks to iancmcci's txrestapi project. An ealier version of this project was available on pypi, but it has not been updated since 2015. The github repository is likewise a little stale but provided some great code to start with. This project's txrestapi subdirectory contains much of the original code, readme, and license file and has been cleaned up to run primarily on Python 3 with fewer imports.