step ssh certificate

step ssh certificate -- sign a SSH certificate using the SSH CA

step ssh certificate command generates an SSH key pair and creates a certificate using step certificates.

With a certificate clients or servers may trust only the CA key and verify its signature on a certificate rather than trusting many user/host keys.

Note that not all the provisioner types will be able to generate user and host certificates. Currently JWK provisioners can generate both, but with an OIDC provisioner you will only be able to generate user certificates unless you are and admin that can generate both. With a cloud identity provisioner you will only be able to generate host certificates.

To configure a server to accept user certificates and provide a user certificate you need to add the following lines in /etc/ssh/sshd_config:

Make sure to restart the sshd daemon to refresh its configuration.

To configure clients to accept host certificates you need to add the host CA public key in ~/.ssh/known_hosts with the following format:

Where *.example.com is a pattern that matches the hosts and ecdsa-sha2-nistp256 AAAAE...= should be the contents of the host CA public key.

key-id The certificate identity. If no principals are passed we will use the key-id as a principal, if it has the format abc@def then the principal will be abc.

key-file The private key name when generating a new key pair, or the public key path when we are just signing it.

-f, --force Force the overwrite of files without asking.

--insecure

--no-password Do not ask for a password to encrypt a private key. Sensitive key material will be written to disk unencrypted. This is not recommended. Requires --insecure flag.

--not-before=time|duration The time|duration when the certificate validity period starts. If a time is used it is expected to be in RFC 3339 format. If a duration is used, it is a sequence of decimal numbers, each with optional fraction and a unit suffix, such as "300ms", "-1.5h" or "2h45m". Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h".

--not-after=time|duration The time|duration when the certificate validity period ends. If a time is used it is expected to be in RFC 3339 format. If a duration is used, it is a sequence of decimal numbers, each with optional fraction and a unit suffix, such as "300ms", "-1.5h" or "2h45m". Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h".

--offline Creates a certificate without contacting the certificate authority. Offline mode uses the configuration, certificates, and keys created with step ca init, but can accept a different configuration file using --ca-config flag.

--provisioner=name, --issuer=name The provisioner name to use.

--token=token The one-time token used to authenticate with the CA in order to create the certificate.

--set=key=value The key=value pair with template data variables. Use the --set flag multiple times to add multiple variables.

--set-file=file The JSON file with the template data variables.

--console Complete the flow while remaining inside the terminal.

--add-user Create a user provisioner certificate used to create a new user.

--host Create a host certificate instead of a user certificate.

--host-id=UUID Specify a UUID to identify the host rather than using an auto-generated UUID. If "machine" is passed, derive a UUID from "/etc/machine-id."

--password-file=file The path to the file containing the password to encrypt the private key.

--principal=name, -n=name Add the specified principal (user or host names) to the certificate request. This flag can be used multiple times. However, it cannot be used in conjunction with '--token' when requesting certificates from OIDC, JWK, and X5C provisioners, or from any provisioner with 'disableCustomSANs' set to 'true'. These provisioners will use the contents of the token to determine the principals.

--private-key=value When signing an existing public key, use this flag to specify the corresponding private key so that the pair can be added to an SSH Agent.

--provisioner-password-file=file The path to the file containing the password to decrypt the one-time token generating key.

--sign Sign the public key passed as an argument instead of creating one.

--kty=kty The kty to build the certificate upon. If unset, default is EC.

kty is a case-sensitive string and must be one of:

--crv=curve, --curve=curve The elliptic curve to use for EC and OKP key types. Corresponds to the "crv" JWK parameter. Valid curves are defined in JWA [RFC7518]. If unset, default is P-256 for EC keys and Ed25519 for OKP keys.

curve is a case-sensitive string and must be one of:

--size=size The size (in bits) of the key for RSA and oct key types. RSA keys require a minimum key size of 2048 bits. If unset, default is 2048 bits for RSA keys and 128 bits for oct keys.

--comment=value The comment used when adding the certificate to an agent. Defaults to the subject if not provided.

--kms=uri The uri to configure a Cloud KMS or an HSM.

--x5c-cert=chain Certificate (chain) in PEM format to store in the 'x5c' header of a JWT.

--x5c-key=file Private key file, used to sign a JWT, corresponding to the certificate that will be stored in the 'x5c' header.

--x5c-chain=file Certificate file, in PEM format

--nebula-cert=file Certificate file in PEM format to store in the 'nebula' header of a JWT.

--nebula-key=file Private key file, used to sign a JWT, corresponding to the certificate that will be stored in the 'nebula' header.

--k8ssa-token-path=file Configure the file from which to read the kubernetes service account token.

--no-agent Do not add the generated certificate and associated private key to the SSH agent.

--ca-config=file The certificate authority configuration file. Defaults to $(step path)/config/ca.json

--ca-url=URI URI of the targeted Step Certificate Authority.

--root=file The path to the PEM file used as the root certificate authority.

--context=name The context name to apply for the given command.

Generate a new SSH key pair and user certificate:

Generate a new SSH key pair and user certificate and do not add to SSH agent:

Generate a new SSH key pair and user certificate and set the lifetime to 2hrs:

Generate a new SSH key pair and user certificate and set the lifetime to begin 2hrs from now and last for 8hrs:

Sign an SSH public key and generate a user certificate:

Generate a new SSH key pair and host certificate:

Sign an SSH public key and generate a host certificate:

Sign an SSH public key and generate a host certificate with a custom uuid:

Sign an SSH public key and generate a host certificate with a uuid derived from '/etc/machine-id':

Generate an ssh certificate with custom principals from an existing key pair and add the certificate to the ssh agent:

Generate a new key pair and a certificate using a given token:

Create an EC pair with curve P-521 and certificate:

Create an Octet Key Pair with curve Ed25519 and certificate: