gnupg-curl software package provides GNU privacy guard - a free PGP replacement (cURL), 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 gnupg-curl
gnupg-curl is installed in your system.
Make ensure the gnupg-curl package were installed using the commands given below,
$ sudo dpkg-query -l | grep gnupg-curl *
You will get with gnupg-curl package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Utilities |
| Package | gnupg-curl |
| Version | 1.4.20-6 |
| Description | GNU privacy guard - a free PGP replacement (cURL) |
| Sub Section | Utils |