Introduction
CADONFS is a complete implementation in C/C++ of the Number Field Sieve (NFS) algorithm for factoring integers. It consists in various programs corresponding to all the phases of the algorithm, and a general script that runs them, possibly in parallel over a network of computers. Starting with version 2.0 there are some functionalities for computing discrete logarithms in finite fields. CADONFS is distributed under the Gnu Lesser General Public License (LGPL) version 2.1 (or any later version).
CADONFS is the result of a collaborative effort involving many persons, over various periods of time. The current list of active contributors can be extracted from the git repository or from the openhub.net page. A tentative list of CADONFS authors is (alphabetical order):


Citing CADONFS
The recommended way to cite CADONFS in a scientific publication is (bibtex entry):
 The CADONFS Development Team. CADONFS, An Implementation of the Number Field Sieve Algorithm, Release 2.2.0, 2015, http://cadonfs.gforge.inria.fr/
where the release number and date should be changed to correspond to the version you actually used. If you used the development version, it is a good idea to give the git revision number.
Features
Algorithms used in CADONFS 2.2.0 are the following:
 The polynomial selection uses the algorithm of Kleinjung (2008) then candidate polynomials are optimized using the algorithm of Bai, Bouvier, Kruppa and Zimmermann (2014)
 The filtering step follows Cavallar's thesis and Bouvier's work. Right now it is partly parallel.
 Relation search is done using lattice sieving, including multithread support to reduce memory.
 The linear algebra step is implemented using block Wiedemann algorithm. This implementation is parallel at multithread and MPI levels.
 The square root step uses the naive algorithm and is parallel. An alternate (experimental) implementation is available for very large computations, or pathological Galois groups.
Speed comparison of CADONFS versions 1.1 and 2.0, obtained on a dual
8core Intel(R) Xeon(R) CPU E52650 at 2.00GHz, running Linux 3.2.0.
Both CADO releases were compiled with gcc 4.7.2.
With CADONFS 1.1 using cadofactor.pl, the timing runs used 16 processes
of 1 thread each for polynomial selection and 8 processes of 2 threads
each for sieving;
with CADONFS 2.0 using cadofactor.py, both phases used 8 processes of
two threads each,
with CADONFS 2.1 using ./factor.sh N s 8 t 2.
With CADONFS 2.3, the same behavior is obtained with ./cadonfs.py
clientthreads 2 serverthreads 16 slaves 8.
The table below lists CPU time [wall clock time in square brackets].
Input number  CADONFS 1.1  CADONFS 2.0  CADONFS 2.1  CADONFS 2.2.0  CADONFS 2.3.0 

RSA120  100 hours  45.6 hours  43.6 hours [4.3 hours]  32.2 hours [2.2 hours]  25.8 hours [1.8 hours] 
RSA130  288 hours  231 hours  219 hours [18.5 hours]  124 hours [8.2 hours]  107 hours [7.2 hours] 
RSA140  809 hours  614 hours  597 hours [49.4 hours]  469 hours [30.9 hours]  351 hours [23 hours] 
RSA155  268 days  141 days  126 days [12.2 days]  90 days [5.8 days]  82 days [5.2 days] 
For 85 to 100digits, Ben Buhrow compared various QS and NFS tools, see here.
You can browse into the development tree history to find the NEWS file for past releases:
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