All three key types are the same in form—Shim's built-in keys and MOKs are both generated using the same tools used to generate Secure Boot keys. The keys can be generated with the common openssl program, but signing EFI binaries requires either of two rarer programs: sbsign or pesign. If you use Shim with a distribution that doesn't support. Nov 30, 2015  Generating Your Own Keys. Secure boot keys are self-signed 2048-bit RSA keys, in X.509 certificate format. Note that most implementations do not support key lengths greater than 2048 bits at present. You can generate a 2048-bit keypair (with a validity period of 3650 days, or ten years) with the following openssl command. Jul 29, 2019 Establishing an SSH (Secure Shell) connection is essential to log in and effectively manage a remote server. Encrypted keys are a set of access credentials used to establish a secure connection. This guide will walk you how to generate SSH keys on Ubuntu 18.04.

1. Secure Boot Windows 10
2. Ubuntu Secure Boot Uefi
3. Secure Ubuntu Server

This section details secure boot in combination with shim (usually provided via the shim-signed package).If you choose another method (e.g. via PreLoader), please refer to the instructions provided by your distribution.For instructions to use PreLoader with HashTool on Gentoo, have a look at https://www.phuntoo.org/surface#uefisecureboot.As of 2019-09-29, new binary kernel releases (for Debian and Arch Linux) will be signed with one of our secure boot certificates, to allow easier installation and updates.

If you have Secure Boot enabled in the BIOS, then it's not possible to boot in insecure mode. Secure Boot causes the system's UEFI firmware to refuse to boot from any bootloader that isn't signed. You shouldn't have to mess with embedded keys and certificates for Secure Boot, because newer Ubuntu bootloaders are signed by an authority whose certificate is already included by default on systems that use Secure. Set policy for how frequently will you be rekeying keys Have a contingency plan for Secure Boot Key compromise Identify how many PK and other keys will you be generating Use HSM to pre-generate secure boot related keys and certificates Get the Microsoft KEK and other Secure Boot related keys and certificates Sign UEFI drivers.

The idea of secure boot is to only allow trusted software to boot on your PC, and thus lock out potential viruses and rootkits that would otherwise be undetectable by our operating system.As custom kernels, such as this one, can be built and distributed by anyone, they are considered not trustworthy by your bootloader, and thus, if you have secure boot enabled, won't be allowed to boot.Luckily there are methods to establish that trust with your bootloader, however, this also means that you have to go through some extra hoops.In the following, we will focus on shim, the default way to achieve this on Ubuntu, Debian, and Fedora.Please refer to the instructions provided by your distribution on how to set this up.Note that in some cases, this might already be set up for you.shim is a chainloader (usually) signed by Microsoft, meaning it is inherently trusted by your bootloader and can be used to load other EFI binaries (i.e. kernels) which it deems trustworthy.To tell shim that a kernel is trustworthy, we will, in the following, use signatures via public and private keys.

Using the Provided Secure Boot Certificate

For your convenience, future (as of 2019-09-29) binary kernel releases will be pre-signed with one of our secure boot keys.You can find the corresponding public key here: linux-surface/linux-surface/keys/MOK.cer

If you use/plan to use secure boot, please make sure that you have enrolled this key before attempting to boot the signed kernel.To help you enroll this key, we provide packages (linux-surface-secureboot-mok for Debian and Arch Linux based distributions or linux-surface-secureboot for Fedora based distributions) in the corresponding package repositories, which install the key and guide you through the enrollment process.

If you use Arch, or one of its derivates, you have to setup secureboot first, before you can enroll the linux-surface key. You need to install a signed shim binary from the AUR, generate a custom keypair to sign the bootloader with and enroll it before installing linux-surface-secureboot-mok. Please refer to the Arch Wiki entry about secureboot for more information.

UEFI Secure boot is a verification mechanism for ensuring that code launched by firmware is trusted. Proper, secure use of UEFI Secure Boot requires that each binary loaded at boot is validated against known keys, located in firmware, that denote trusted vendors and sources for the binaries, or trusted specific binaries that can be identified. Set policy for how frequently will you be rekeying keys Have a contingency plan for Secure Boot Key compromise Identify how many PK and other keys will you be generating Use HSM to pre-generate secure boot related keys and certificates Get the Microsoft KEK and other Secure Boot related keys and certificates Sign UEFI drivers.

Manually Enrolling a Public Key

To manually enroll a public key, we recommend using the mokutil tool (install mokutil-git for Arch Linux).Via this, you can manage your trusted secure boot certificates, e.g. view, enroll, or delete them.To enroll a public key, you need it in x509 DER format (the links above already provide this format).You can then enroll it using

During this, you will get asked for a password.You can freely choose it, but you will need to remember it to complete the process and manage your key.To finalize this operation, you need to reboot, which will then bring you to the MokManager tool.Here, you can finally enroll this key via the Enroll key option, which you need to confirm with your chosen password.Please make sure that this is indeed the key you want to enroll.

If you do not trust this key any more, you can delete/revoke it via

You, again, need to choose a password and reboot to complete this operation inside the MokManager tool.

Using your own Key Pair

Please note that this is not intended as an exhaustive tutorial, but rather as a quick overview of what to do.As always, please consult the instructions provided by your distribution in addition to this.To create your own keys you will need openssl, to sign your kernel you will need sbsign, usually provided by the sbsigntool package (sbsigntools on Arch Linux).

First, you will need to create your own public and private keys.The private key will be used to sign the kernel, whereas the public key will be used by shim to verify this signature.If you do not know anything about public and private key cryptography, please note that the private key is, as the name implies, to be kept private.If you have enrolled the corresponding public key, anyone with this private key can sign kernels that will then be allowed to boot on your system.In short, handing over your private key is like handing over your passport.

To create the key pair, run

You may want to adapt the output file names, subject line, and duration of validity (days) to your liking.To use the public key with mokutil, you next need to convert it to DER form via

You should now enroll this key as described in 'Manually Enrolling a Public Key', however, you can delay the restart until after you have signed the kernel.To finally sign the kernel, run

where [KERNEL-SUFFIX] is the version and suffix of the kernel you want to sign.

If you have not done so before installing the kernel, update your bootloader config (e.g. for GRUB run sudo update-grub), reboot, and finish the key enrollment process if not completed already.Please note that you will need to re-run the sbsign command each time you update your kernel and thus you should keep your generated keys (MOK.key, MOK.crt, and MOK.cer) secure and safe.

For further information, you may want to look at the Arch Linux wiki entry or this Ubuntu blog entry.

Snipe-it generate app key windows. Parent page: Internet and Networking >> SSH

Public key authentication is more secure than password authentication. This is particularly important if the computer is visible on the internet. If you don't think it's important, try logging the login attempts you get for the next week. My computer - a perfectly ordinary desktop PC - had over 4,000 attempts to guess my password and almost 2,500 break-in attempts in the last week alone.

With public key authentication, the authenticating entity has a public key and a private key. Each key is a large number with special mathematical properties. The private key is kept on the computer you log in from, while the public key is stored on the .ssh/authorized_keys file on all the computers you want to log in to. When you log in to a computer, the SSH server uses the public key to 'lock' messages in a way that can only be 'unlocked' by your private key - this means that even the most resourceful attacker can't snoop on, or interfere with, your session. As an extra security measure, most SSH programs store the private key in a passphrase-protected format, so that if your computer is stolen or broken in to, you should have enough time to disable your old public key before they break the passphrase and start using your key. Wikipedia has a more detailed explanation of how keys work.

Public key authentication is a much better solution than passwords for most people. In fact, if you don't mind leaving a private key unprotected on your hard disk, you can even use keys to do secure automatic log-ins - as part of a network backup, for example. Different SSH programs generate public keys in different ways, but they all generate public keys in a similar format:

Key-based authentication is the most secure of several modes of authentication usable with OpenSSH, such as plain password and Kerberos tickets. Key-based authentication has several advantages over password authentication, for example the key values are significantly more difficult to brute-force, or guess than plain passwords, provided an ample key length. Other authentication methods are only used in very specific situations.

SSH can use either 'RSA' (Rivest-Shamir-Adleman) or 'DSA' ('Digital Signature Algorithm') keys. Both of these were considered state-of-the-art algorithms when SSH was invented, but DSA has come to be seen as less secure in recent years. RSA is the only recommended choice for new keys, so this guide uses 'RSA key' and 'SSH key' interchangeably.

Key-based authentication uses two keys, one 'public' key that anyone is allowed to see, and another 'private' key that only the owner is allowed to see. To securely communicate using key-based authentication, one needs to create a key pair, securely store the private key on the computer one wants to log in from, and store the public key on the computer one wants to log in to.

Using key based logins with ssh is generally considered more secure than using plain password logins. This section of the guide will explain the process of generating a set of public/private RSA keys, and using them for logging into your Ubuntu computer(s) via OpenSSH.

The first step involves creating a set of RSA keys for use in authentication.

This should be done on the client.

To create your public and private SSH keys on the command-line:

You will be prompted for a location to save the keys, and a passphrase for the keys. This passphrase will protect your private key while it's stored on the hard drive:

Your public key is now available as .ssh/id_rsa.pub in your home folder.

Congratulations! You now have a set of keys. Now it's time to make your systems allow you to login with them

Choosing a good passphrase

You need to change all your locks if your RSA key is stolen. Otherwise the thief could impersonate you wherever you authenticate with that key.

An SSH key passphrase is a secondary form of security that gives you a little time when your keys are stolen. If your RSA key has a strong passphrase, it might take your attacker a few hours to guess by brute force. That extra time should be enough to log in to any computers you have an account on, delete your old key from the .ssh/authorized_keys file, and add a new key.

Your SSH key passphrase is only used to protect your private key from thieves. It's never transmitted over the Internet, and the strength of your key has nothing to do with the strength of your passphrase.

The decision to protect your key with a passphrase involves convenience x security. Note that if you protect your key with a passphrase, then when you type the passphrase to unlock it, your local computer will generally leave the key unlocked for a time. So if you use the key multiple times without logging out of your local account in the meantime, you will probably only have to type the passphrase once.

If you do adopt a passphrase, pick a strong one and store it securely in a password manager. You may also write it down on a piece of paper and keep it in a secure place. If you choose not to protect the key with a passphrase, then just press the return when ssh-keygen asks.

Key Encryption Level

Note: The default is a 2048 bit key. You can increase this to 4096 bits with the -b flag (Increasing the bits makes it harder to crack the key by brute force methods).

Password Authentication

The main problem with public key authentication is that you need a secure way of getting the public key onto a computer before you can log in with it. If you will only ever use an SSH key to log in to your own computer from a few other computers (such as logging in to your PC from your laptop), you should copy your SSH keys over on a memory stick, and disable password authentication altogether. If you would like to log in from other computers from time to time (such as a friend's PC), make sure you have a strong password.

Secure Boot Windows 10

The key you need to transfer to the host is the public one. If you can log in to a computer over SSH using a password, you can transfer your RSA key by doing the following from your own computer:

Where <username> and <host> should be replaced by your username and the name of the computer you're transferring your key to.

Due to this bug, you cannot specify a port other than the standard port 22. You can work around this by issuing the command like this: ssh-copy-id '<username>@<host> -p <port_nr>'. If you are using the standard port 22, you can ignore this tip.

Another alternative is to copy the public key file to the server and concatenate it onto the authorized_keys file manually. It is wise to back that up first:

You can make sure this worked by doing:

You should be prompted for the passphrase for your key:

Enter your passphrase, and provided host is configured to allow key-based logins, you should then be logged in as usual.

Encrypted Home Directory

If you have an encrypted home directory, SSH cannot access your authorized_keys file because it is inside your encrypted home directory and won't be available until after you are authenticated. Therefore, SSH will default to password authentication.

To solve this, create a folder outside your home named /etc/ssh/<username> (replace '<username>' with your actual username). This directory should have 755 permissions and be owned by the user. Move the authorized_keys file into it. The authorized_keys file should have 644 permissions and be owned by the user.

Then edit your /etc/ssh/sshd_config and add:

Finally, restart ssh with:

The next time you connect with SSH you should not have to enter your password.

Ubuntu Secure Boot Uefi

username@host's password:

If you are not prompted for the passphrase, and instead get just the

prompt as usual with password logins, then read on. There are a few things which could prevent this from working as easily as demonstrated above. On default Ubuntu installs however, the above examples should work. If not, then check the following condition, as it is the most frequent cause:

On the host computer, ensure that the /etc/ssh/sshd_config contains the following lines, and that they are uncommented;

If not, add them, or uncomment them, restart OpenSSH, and try logging in again. If you get the passphrase prompt now, then congratulations, you're logging in with a key!

Permission denied (publickey)

If you're sure you've correctly configured sshd_config, copied your ID, and have your private key in the .ssh directory, and still getting this error:

Chances are, your /home/<user> or ~/.ssh/authorized_keys permissions are too open by OpenSSH standards. You can get rid of this problem by issuing the following commands:

Error: Agent admitted failure to sign using the key.

This error occurs when the ssh-agent on the client is not yet managing the key. Issue the following commands to fix:

This command should be entered after you have copied your public key to the host computer.

Secure Ubuntu Server

Debugging and sorting out further problems

The permissions of files and folders is crucial to this working. You can get debugging information from both the client and server.

if you think you have set it up correctly , yet still get asked for the password, try starting the server with debugging output to the terminal.

To connect and send information to the client terminal

No matter how your public key was generated, you can add it to your Ubuntu system by opening the file .ssh/authorized_keys in your favourite text editor and adding the key to the bottom of the file. You can also limit the SSH features that the key can use, such as disallowing port-forwarding or only allowing a specific command to be run. This is done by adding 'options' before the SSH key, on the same line in the authorized_keys file. For example, if you maintain a CVS repository, you could add a line like this:

When the user with the specified key logged in, the server would automatically run /usr/bin/cvs server, ignoring any requests from the client to run another command such as a shell. For more information, see the sshd man page. /755