websession.rs

Web Session Support for Rust

Overview

websession provides a simple interface to web session management, with reliably encrypted passwords (currently bcrypt) and automatically expiring identifiers.

Users can be identified by any UTF-8, including a username, an email address, a number, or anything else you can think of that does not contain an embedded : (as : is used as the delimiter in the FileBackingStore and prohibited by the MemoryBackingStore for compatibility reasons).

Be advised that as of 0.6.0, the FileBackingStore and the MemoryBackingStore silently replace "\n" with "\u{FFFD}", just as String::from_utf8_lossy does for invalid UTF-8. This is unlikely to cause problems in production because users with embedded newlines in their name already can't log in properly.

It is expected that metadata (real names, contact information, user-based permissions, etc.) are managed by the consuming app.

Usage

To use this software, you need to select a BackingStore implementation.

The FileBackingStore needs an existing file which will contain identifiers and passwords. At a minimum, you can use an empty file and then add users to it. See the test in backingstore.rs for syntax. This file will persist across runs, and is assumed by the implementation to have appropriate read/write permissions.

If you use the MemoryBackingStore, changes will not persist across restarts.

Implementation Notes

Implementations of the BackingStore trait are responsible for appropriate management of passwords and especially not to store them in plaintext. The provided implementations do not store plaintext passwords on disk (and the MemoryBackingStore attempts not to save plaintext passwords in memory). [N.B., preventing a leak of unencrypted passwords to swap space is beyond the scope of this project, though we would welcome pull requests that reduce the probability of such a leak.]

Some effort is made to protect the FileBackingStore's file by copying the mode of the existing file when rewriting it, but this is only implemented under UNIX-like operating systems. A pull request which sets appropriate file permissions under Windows would be gratefully accepted.

bcrypt Notes

The default implementation uses eight (8) rounds of bcrypt. You should run cargo bench to see how long it takes to run bcrypt on your target system. If 8 rounds takes less than 0.01 seconds (10,000,000 nanoseconds) or more than 0.25 seconds (250,000,000, you should use implement your own BackingStore which uses more or fewer rounds, as needed (or, of course, a different encryption method). (Each additional round doubles computation time, so increase the number by 2 to quadruple the time per hash or decrease it by 2 to quarter the time per hash.)

Licensing

This software is dual-licensed under the Apache and MIT licenses.