agent-transfer software package provides copy a secret key from GnuPGs gpg-agent to OpenSSHs ssh-agent, 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 agent-transfer
agent-transfer is installed in your system.
Make ensure the agent-transfer package were installed using the commands given below,
$ sudo dpkg-query -l | grep agent-transfer *
You will get with agent-transfer package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Network |
| Package | agent-transfer |
| Version | 0.40-2 |
| Description | copy a secret key from GnuPGs gpg-agent to OpenSSHs ssh-agent |
| Sub Section | Net |