argon2 software package provides memory-hard hashing function - utility, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install argon2
argon2 is installed in your system.
Make ensure the argon2 package were installed using the commands given below,
$ sudo dpkg-query -l | grep argon2 *
You will get with argon2 package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Libraries |
| Package | argon2 |
| Version | 0~20160821-1 |
| Description | memory-hard hashing function - utility |
| Sub Section | Libs |