release of the toolkit , used to organize the work of the anonymous Tor network. Tor 0.4.1.5 is recognized as the first stable release of the 0.4.1 branch, which has been in development for the past four months. The 0.4.1 branch will be maintained according to the standard support cycle — updates will cease 9 months after release or 3 months after the release of the 0.4.2.x branch. Long-term support (LTS) is provided for the 0.3.5 branch, with updates being released until February 1, 2022.
Key innovations:
- Experimental support for padding at the chain level has been implemented, allowing for enhanced protection against traffic analysis methods for Tor. The client now adds padding cells at the beginning of the chains , making the traffic of these chains more similar to normal outgoing traffic. The cost of this increased protection is the addition of two extra cells in each direction for RENDEZVOUS chains, as well as one upstream and 10 downstream cells for INTRODUCE chains. This method is activated by specifying the MiddleNodes option in the settings and can be disabled via the CircuitPadding option;
- support for authenticated SENDME cells to protect against , based on creating parasitic load when the client requests the download of large files and pauses reading operations after sending requests, but continues to send SENDME control commands instructing entry nodes to continue delivering data. Each cell
SENDME now includes a traffic hash that it confirms, and the exit node upon receiving the SENDME cell can ensure that the other party has already received the traffic sent during the processing of previous cells; - The implementation of a generalized subsystem for message transmission in publisher-subscriber mode has been included, which can be used for intra-module interaction;
- A generalized parsing subsystem for processing control commands has been employed instead of separate parsing for the input data of each command;
- Performance optimization has been implemented, reducing the load on the CPU. Tor now uses a separate fast pseudorandom number generator (PRNG) for each thread, based on the AES-CTR encryption mode and utilizing buffering constructs as in libottery and the new arc4random() code from OpenBSD. For small outputs, the proposed generator works nearly 100 times faster than the CSPRNG from OpenSSL 1.1.1. While the new PRNG is considered cryptographically secure by Tor developers, it is currently only used in areas requiring high performance, such as in the code for scheduling padding attachment.
- The option "--list-modules" has been added to output a list of enabled modules.
- For the third version of the hidden services protocol, the HSFETCH command has been implemented, which was previously supported only in the second version.
- Errors in the Tor bootstrap code have been fixed to ensure the functionality of the third version of the hidden services protocol.
Source: opennet.ru
