Primo is a primality proving program based on the ECPP (Elliptic Curve Primality Proving) algorithm. Given positive odd integers, it tests whether these integers are prime, and if they are it produces primality certificates. With Primo, one can check crypto-primes and prove whether they are actually prime... or not.

Executable for Linux 64-bit (Ubuntu 16.04/x86-64 architecture)
Compiled with Free Pascal 3.0.0 and Lazarus 1.6.0
Primo for Linux screenshot

A short description of the ECPP algorithm can be found at Elliptic Curve Primality Proving by Eric Weisstein (from MathWorld — A Wolfram Web Resource).

  • What does "LX64" stand for?
    Linux 64-bit.
  • Does it exist a Primo version for an other operating system than Linux?
    No, there is not and there will not be. (Why paying for an OS? Linux is free.)
  • Is the LX64 version for multicore processors?
    Yes, it is. It can work with up to 48 processors.
  • Does the LX64 version run with Linux distributions other than Ubuntu 16.04?
    It should do (but I do not know).
  • Does it exist a command line version?
    No, there is not and I do not plan to write a one.

v4.3.0 (February 21, 2018)
  • Maximal size of candidates increased up to 132,928 bits (~ 40,000 decimal digits).
  • Modified the "Phase 1" strategy. There are now three possible passes (due to this modification, the binary format of the .t files was modified making impossible to resume a certification started with a previous version of Primo). The goal was to produce smaller certificates that are slightly faster to check.
  • Modified the "Phase 2" strategy. The tests are now sorted in order to improve the parallelization.
  • Modified the "Setup" dialog box.
  • Modified the primo.ini file structure.
  • Modified the primo.html help file.
  • Added data in order to speed a little up polynomial factorizations.
  • Suppressed the certification report generation (i.e., no more .cr files).
  • Suppressed the cumbersome and useless "extended factorization" stuff.
  • Fixed a bug that could raise the internal error Thanks to Tom Wu who reported it.
  • Fixed bugs that could raise the internal errors, and Thanks to Ed Hall who reported them.
 Previous changes


The software Primo may be used free of charge but it might be a good idea to read the End-User License Agreement before downloading and using it.

Due to numerous changes, it is impossible to resume with the 4.3.0 version a certification started with a previous version.

  primo-430-lx64.7z    32.7 MB   Executables  (binary files)

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