ssh-scepclient-g3

ssh-scepclient-g3 — SCEP enrollment client

Synopsis

ssh-scepclient-g3 command [options] access [name]

Where command is one of the following:
     GET-CA
     GET-CHAIN
     ENROLL psk keypair template

Most commands can accept the following options:
     -o prefix       Save result into files with prefix.
     -S url          Use this socks server to access CA.
     -H url          Use this HTTP proxy to access CA.

The following identifiers are used to specify options:
     psk      -p key (used as revocationPassword or challengePassword)
     keypair  -P url (private-key URL)
     ca       -C file (CA certificate file)
              -E file (RA encryption certificate file)
              -V file (RA validation certificate file)
     template -T file (certificate template)
              -s subject-ldap[;type=value]
              -u key-usage-name[;key-usage-name]
              -U extended-key-usage-name[;extended-key-usage-name]
     access   URL where the CA listens for requests.

GET-CA and GET-CHAIN take name argument, that is something
interpreted by the CA to specify a CA entity managed by the responder.

Key URLs are either valid external key paths or in the format:
     "generate://savetype:password@keytype:size/save-file-prefix"
     "file://savetype:password@/file-prefix"
     "file://passphrase/file-prefix"
     "file:/file-prefix"
     "key-filename"

The "keytype" for the SCEP protocol has to be "rsa".

The key generation "savetype" can be:
 - ssh2 (Secure Shell 2 key type)
 - ssh1 (Legacy Secure Shell 1 key type)
 - ssh  (SSH proprietary crypto library format, passphrase-protected)
 - pkcs1 (PKCS#1 format)
 - pkcs8s (passphrase-protected PKCS#8, "shrouded PKCS#8")
 - pkcs8 (plain-text PKCS#8)
 - x509 (SSH proprietary X.509 library key type)

Description

The ssh-scepclient-g3 command-line tool (ssh-scepclient-g3.exe on Windows) is a certificate enrollment client that uses the SCEP protocol. It can generate an RSA public-key pair and get certificates for its public components. The SCEP protocol was developed by Cisco and Verisign to be used on Cisco routers. Nowadays most CA platforms support this protocol for client certificate enrollment.

Commands

The ssh-scepclient-g3 command-line command keywords are listed below. Shorthands longer than three letters can be used to identify the command. The commands are case-insensitive. The user must specify the CA address URL for each command. Here the term "user" refers to a user, program, or hardware device.

GET-CA: Requests CA or RA certificate download from the CA, and display the certificate fingerprint for CA validation. Fingerprints should be received from the CA using some out-of-band mechanism.
GET-CHAIN: Requests certificate chain from the CA/RA to the top-level CA.
ENROLL: Requests a new certificate from the CA. The CA will authorize the request using some out-of-band mechanism, or it can contain a password received from the CA.

Options

-o prefix: Saves output certificates into files with the given prefix. The prefix is first appended by a number, followed by the file extension .ca for CA certificates or .crt for user certificates.
-S url: Specifies the SOCKS URL if the CA is located behind a SOCKS-enabled firewall. The format of the URL is: socks://[username@]server[:port][/network/bits[,network/bits]]
-H url: Uses the given HTTP proxy server to access the CA. The format of the URL is: http://server[:port]/.

The usage line uses the following meta commands:

psk

The pre-shared key given by the CA or RA, or a revocation password invented by the client and provided to the CA when the user wishes to revoke the certificate issued. The type and need for this depends on the PKI platform used by the CA.

-p key: An authentication password or a revocation password transferred (in encrypted format) to the CA for certification request or revocation request authorization purposes.

keypair

The subject key pair to be certified.

-P url: URL specifying the private key location. This is an external key URL whose format is specified in the section called “Synopsis”.

ca

The CA/RA certificates.

-C file: When performing enrollment, reads the CA certificate from the given file path.
-E file: Optionally specifies the RA encryption certificate.
-V file: Optionally specifies the RA signing certificate.

template

The subject name and flags to be certified.

-T file

The file containing the certificate used as the template for the operation. Values used to identify the subject are read from this, but the user may overwrite the key, key-usage flags, or subject names.

-s subject-ldap[;type=value]*

A subject name in reverse LDAP format, that is, the most general component first, and alternative subject names. The name subject-ldap will be copied into the request verbatim.

A typical choice would be a DN in the format "C=US,O=SSH,CN=Some Body", but in principle this can be anything that is usable for the resulting certificate.

The possible type values are ip, email, dn, dns, uri, and rid.

-u key-usage-name[;key-usage-name]*

Requested key usage purpose code. The following codes are recognized: digitalSignature, nonRepudiation, keyEncipherment, dataEncipherment, keyAgreement, keyCertSign, cRLSign, encipherOnly, decipherOnly, and help. The special keyword help lists the supported key usages which are defined in RFC 3280.

-U extended-key-usage-name[;extended-key-usage-name]*

Requested extended key usage code. The following codes, in addition to user-specified dotted OID values are recognized: serverAuth, clientAuth, codeSigning, emailProtection, timeStamping, ikeIntermediate, and smartCardLogon.

access

Specifies the address of the CA in URL format. If the host address is an IPv6 address, it must be enclosed in brackets (http://[IPv6-address]:port/).

name

Specifies the destination CA name.

Examples

In the following example we first receive the CA certificate. The CA address is pki.ssh.com, the port is 8080, and the CA name is test-ca1.ssh.com.

$ ssh-scepclient-g3 GET-CA \ 
   -o ca http://pki.ssh.com:8080/scep/ \
   test-ca1.ssh.com

Received CA/RA certificate ca-0.ca:

fingerprint 9b:96:51:bb:29:0d:c9:e0:75:c8:03:0d:0d:92:60:6c

Next, we enroll an RSA certificate. The user is authenticated to the CA with the key ssh. The subject name and alternative IP address are given, as well as key-usage flags.

$ ssh-scepclient-g3 ENROLL \
    -C ca-0.ca -p ssh \
    -o subject -P generate://pkcs8:ssh@rsa:1024/subject \
    -s 'C=FI,O=SSH,CN=SCEP Example;IP=1.2.3.4' \
    -u digitalsignature \
    http://pki.ssh.com:8080/scep/

Received user certificate subject-0.crt: 
fingerprint 4b:7e:d7:67:27:5e:e0:54:2f:5b:56:69:b5:01:d2:15
$ ls subject*
subject-0.crt   subject.prv