Use openpgp keys for openssh, how to use gpg with ssh this is, section howto, feedback to. Encryption part 4 sign git commits and ssh with piv. Use openpgp keys for openssh, how to use gpg with ssh. As mentioned, switching to this smartcard will be required whenever you want to sign somebody elses key or make modifications to your key. After the setup the smart cards key shows up in gpg listsecretkeys output. Gpg and ssh with yubikey for mac richard norths blog. Configuration to use gpg smartcards for ssh authentication lfitssh gpg smartcardconfig. Populating this field will make it much easier to start using the card on our normal computer because well be able to use the fetch command in this menu to add our public key and some private key stubs to our keyring.
Ive gone through the initial setup and i am able to use the smart card to sign and encrypt files. So it can pretend to be a smart card, but it cant read a smart card. Im not sure why this is happening but i can generally fix it by closing kleopatra, killing the gpg agent process, and restarting kleopatra. These in turn can be used by several other useful tools, like git, pass, etc. Cards exist to either run openpgp or x509cms operations. All smart card functionality works with the gpg wsl toolchain. Instead, we can use homebrew to install the required components. If the smart card isnt present then the above operations would fail immediately. You can list public keys on the card directly using ssh keygen.
This guide will help you set up the required software for getting things to work. Nitrokey and yubico provide usb tokens implementing the same protocol through smart card emulation. We are now ready to use our yubikey for ssh authentication. Using a yubikey as smartcard for ssh public key authentication. To configure your system to use a gpg smart card for ssh authentication, visit the appropriate link below. On linux at least, if the other yubikey containing a copy of the same gpg keys is inserted, gpg agent will ask that the correct smartcard be inserted. In part three i detailed how to create a secure environment and then how to create a master gpg key and then create signing, encrypting, and authentication subkeys that exist only on the smart card.
This will reevocably destroy all data stoerd on the card thus also all keys. In order to try this, see the howto links above, you may need to acquire a smartcard and a reader or an integrated combination of both. I didnt buy my smart card so i could use it with ssh. Its been quite a while, but i do recall trying this in the past and having it not work, even when i did not put enablessh in gpg nf. Ssh authentication with gnupg and smart cards netways gmbh. These instructions apply primarily to os x and linux systems. Estonian id card uses opensc project to access private keys on the smart card. Getting estonian id card and gnupg scdaemon yubikey work together. That said, i currently, with the above patches, use gpg for code signingemail signaturesssh authentication and smart card for local login, at the same time with no issues. To obtain the the gemalto usb shell token v2 visit. The users ssh private key will be stored on the yubikey and u2f will be used to authenticate with pritunl zero when obtaining an ssh certificate. This is caused by the fact that if there is more than one smartcard reader in the system, scdaemon just defaults to checking the first one and if that is not a gpg compatible smart card in our case the yubikey, it does not try the other ones. I wanted to use my yubikeys with wsl ssh and gpg toolchains, so i wrote a python wsl gpg bridge to bridge the tcp assuan sockets exposed by the gnupg windows binaries to the usual unix sockets in wsl. Passwordencrypted, ssh keygen o a 500 t ed25519 keys stored within the macs home dir.
This howto describes how to use gnupg with a smart card distributed to fellows of the free software foundation europe. Smart cards are designed to wipe themselves after a few failed pin attempts. This document covers the procedure for configurating a system to use gpg smartcards for ssh authentication. This is a decent solution for twofactor authentication. Guide to using yubikey as a smartcard for gpg and ssh. How to use the fellowship smartcard gnu privacy guard. Smart cards are designed so that once the private keys are imported to the device they cannot be extracted. Problems using an openpgp smartcard for ssh with gpg agent 3 replies i have been using an openpgp smartcard for encryption, signing and authentication for over a year now and ive found it to be really useful as a root of trust. If found, that key will be used by the ssh client to authenticate with the remote machine. The yubikey neo is a great, inexpensive security device that supports universal 2nd factor authentication to web services and openpgp smart card support.
In this post, ill show how i recently set up my new openpgp key and smart card. This means that the private key doesnt leave the card. Configuring a gpg smart card for ssh authentication on linux is nontrivial. Hot network questions what prevents laws from being interpreted pedantically. To set up yubikey as a smart card holding your pgp keys, you need first to replace your sshagent that comes preinstalled with macos with a gnupg solution.
Note that i have a total of 3 smartcard readers, with the yubikey counting as its own reader. The benefit is a good model for twofactor authentication, something you have and something you know. Gpg key, along side an ssh key via pivsmartcard, on the. This blog post is now out of date and shouldnt be relied upon. How to use a gpg key for ssh authentication linode. Provision the smartcard with yubicopivtool, install opensc and switch from sshing with gpg rsa enabled 4096 bit keys to pkcs11 module im assuming that these could make use of ecc p384 piv cert generated by either the cli or gui version of yubicopivtool.
I then detailed how to install keybase and then import this externally generated pgp public key. The yubikey 4 and yubikey neo support the openpgp interface for smart cards which can be used with gpg4win for encryption and signing, as well as for ssh authentication. I recently bought a yubikey neo which can act as a openpgp smart card. Smart card support was introduced around 2010 with openssh 5. Since the gpg agent understands about an openpgp smart card, a ssh client requesting the private key will prompt the gpg agent, which looks for an authentication key on the yubikey.
Rationale this post generating more secure gpg keys. To solve this, you will need to add readerport to nf. This tutorial will explain configuring ssh authentication using a yubikey with smart card key storage and u2f authentication. A smart card stores certificates such as your ssh key and provides functionality for operating on those certificates e. The gpg2 stub pointing to the smart card will point to one of the keys only. The documentation also shows how much the developers care. Smart card pins cant be brute forced, so its not a huge security problem if they are lost.
With gpg agent in gnupg 2, an sshagent implementation using gnupg, an openpgp card can be used. First, lets talk about some of the risks of using gpg in the naive way i demonstrated. I have this exact setup working with a yubikey and was a very happy user until i upgraded my mac to highsierra, it would appear with the new native piv integration with osx that the yubikey is hogged by the os and gpg cant get access to read it as a smart card. The smart card daemon, in combination with the supported smart card readers, as implemented in gnupg, can be used for many cryptographic applications. There might be conflict in access to the smart card via the scdaemon process.
A smart card like yubikey is basically a physical device that can store private keys and perform the cryptographic operations directly on the device. You can kill try to disable scdaemon service, and run gpg card. Windows gnupg gpg smart card status not detecting yubikey. The inital scope was restricted to the rsa keys the only supported key type at that time in openssh other than legacy dsa keys. In this example, there is a token and a passphrase. This worked fine, and i could sign and use gnupg as expected. Yeah the yubikey also presents itself as a gpg smart card which of course you can then use for ssh by making your ssh agent env variable point to the gpg agent. In the fourth and final installment of this encryption series, i will explain. All that is required is to plug the yubikey into an usb slot. While editing the card, you can also set other metadata like the card owners name and login. This document covers the procedure for configuring a yubikey as a gpg smartcard for ssh authentication. Keys written to a card can only be used in combination with a pin code, so even if a yubikey is stolen, a thief would not be able to authenticate directly.
After exporting my private key, i moved my private key on a smart card using keytocard. Gpg tools will have added gpg agent to your launchd configuration, so it should already be running. The smart card is then to be shipped off to the user. Problems using an openpgp smartcard for ssh with gpgagent. I purchased it mainly so i could use it for signing and encrypting email. However, ssh1 has another method to talk to smartcards. Especially at work where other peple have root access on your machine it is not save to store your secret key. One field well want to make sure to set is the url to fetch our public key from. How to get public key from an openpgp smart card without using key servers. How to get public key from an openpgp smart card without. Before you can use your existing card, your should import the public key associated with the private key on the card. Ssh is configured to use the smart card socket for authentication, and authenticating with the gpg key with authentication capabilities work fine. Opensc also supports yubikey and that will create conflicts with gnupg scdaemon. In order to deal with this, gpg connectagent has to be told via kleopatra that we want to explicitly use the yubikey reader.