As can be seen the C++ application appears to be much faster than the C# application. Also, in my humble opinion, C++ with header files and C++ source code files is much more elegant than C# with only class source code. I leave it to someone else to add C# interfaces to my class source code files.
A few years ago, I implemented the LLL lattice reduction algorithm found in two references: “Handbook of Applied Cryptography” Edited by Alfred J. Menezes et al and “A Course in Computational Algebraic Number Theory” by Henri Cohen. My new implementation in C# uses 64-bit integers and BigIntegers. Here are some results.
See the following website for the used algorithms pages 119 to 121:
In Winter and Spring 2018 I wrote a simple C# computer program to perform machine cryptanalysis of the following basic (elementary and easily breakable) cryptosystems:
The key ingredient in this program is a relatively extensive English language dictionary.
Numerical Explorations 