FaCT is an actively used programming language created in 2017. FaCT is a domain-specific language that aids you in writing constant-time code for cryptographic routines that need to be free from timing side channels. This is the compiler for the Flexible and Constant Time cryptographic programming language.

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  • FaCT on github
  • FaCT first appeared in 2017
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Example code from the web:

swap_conditional(secret mut uint64[5] a, secret mut uint64[5] b, secret uint64 swapi) {
  if (swapi == 1) {
    for (uint32 i from 0 to 5) {
      secret uint64 x = a[i];
      a[i] = b[i];
      b[i] = x;

Last updated January 24th, 2020

Edit FaCT on GitHub