During using HElib, if the calculation made Ctxt‘s noise too big, it will cause Ctxt can’t be decrypted successfully, and the decrypted result is messy like this:
333317397173303 1016371194582039 217550837977960
737191953777559 1103851234911944 454685807668230
625213263895453 743713807221034 1036409711005678
447878070619549 603715795412661 948856958008786
......
You can leverage Ctxt::isCorrect() method to check whether Ctxt is still valid or not:
std::cout << "Ctxt is valid: " << c.isCorrect() << '\n';
Reference:
Maybe the bug in EncryptedArray’s shift function.