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Last pushed: 8 days ago
Short Description
SCEP server
Full Description

scep is a Simple Certificate Enrollment Protocol server and client

Installation

A binary release is available on the releases page.

Compiling

To compile the SCEP client and server, there are a few requirements.

  • You must have a Go compiler. The compiler is normally in the golang package.
  • You must have a shell variable set for $GOPATH. This is a directory used by the Go compiler and utilities for all Go projects.
  1. Once all of those are set, clone the repository with go get github.com/micromdm/scep
  2. Install dependencies:
    make deps
  3. Compile the server and client binaries:
    make build
    The binaries will be compiled in the build/ folder.

Example

minimal example for both server and client

# create a new CA
scepserver ca -init
# start server
scepserver -depot depot -port 2016 -challenge=secret

# SCEP request:
# in a separate terminal window, run a client
# note, if the client.key doesn't exist, the client will create a new rsa private key. Must be in PEM format.
scepclient -private-key client.key -server-url=http://scep.groob.io:2016/scep -challenge=secret

# NDES request:
scepclient -private-key client.key -server-url=http://scep.groob.io:2016/certsrv/mscep/ -ca-fingerprint="81C827D2 3DAAF3B4 73999632 67609B30"

Server Usage

The default flags configure and run the scep server.
depot must be the path to a folder with ca.pem and ca.key files.

If you don't already have a CA to use, you can create one using the scep ca subcommand.

The server currently has two endpoints:

  • /scep
  • /certsrv/mscep

To obtain a signed SCEP certificate, you will use the /scep endpoint.

To obtain a certificate through Network Device Enrollment Service (NDES), use the /certsrv/mscep endpoint. You will need to add the ca-fingerprint client argument during this request.

Usage of ./cmd/scepserver/scepserver:
  -challenge string
        enforce a challenge password
  -depot string
        path to ca folder (default "depot")
  -port string
        port to listen on (default "8080")
  -version
        prints version information

scep ca -init to create a new CA and private key.

Usage of ./cmd/scepserver/scepserver ca:
  -country string
        country for CA cert (default "US")
  -depot string
        path to ca folder (default "depot")
  -init
        create a new CA
  -key-password string
        password to store rsa key
  -keySize int
        rsa key size (default 4096)
  -organization string
        organization for CA cert (default "scep-ca")
  -years int
        default CA years (default 10)

Client Usage

Usage of scepclient:
  -certificate string
        certificate path, if there is no key, scepclient will create one
  -challenge string
        enforce a challenge password
  -cn string
        common name for certificate (default "scepclient")
  -country string
        country code in certificate (default "US")
  -keySize int
        rsa key size (default 2048)
  -organization string
        organization for cert (default "scep-client")
  -private-key string
        private key path, if there is no key, scepclient will create one
  -server-url string
        SCEP server url
  -version
        prints version information

Note: Make sure to specify the desired endpoint in your -server-url value (e.g. 'http://scep.groob.io:2016/scep')

Docker

docker pull micromdm/scep
# create CA
docker run -it --rm -v /path/to/ca/folder:/depot micromdm/scep ./scep ca -init

# run
docker run -it --rm -v /path/to/ca/folder:/depot -p 8080:8080 micromdm/scep

SCEP library

go get github.com/micromdm/scep/scep

For detailed usage, see godoc

Example:

// read a request body containing SCEP message
body, err := ioutil.ReadAll(r.Body)
if err != nil {
    // handle err
}

// parse the SCEP message
msg, err := scep.ParsePKIMessage(body)
if err != nil {
    // handle err
}

// do something with msg
fmt.Println(msg.MessageType)

// extract encrypted pkiEnvelope
err := msg.DecryptPKIEnvelope(CAcert, CAkey)
if err != nil {
    // handle err
}

// use the csr from decrypted PKCRS request
csr := msg.CSRReqMessage.CSR

// create cert template
tmpl := &x509.Certificate{
    SerialNumber: big.NewInt(1),
    Subject:      csr.Subject,
    NotBefore:    time.Now().Add(-600).UTC(),
    NotAfter:     time.Now().AddDate(1, 0, 0).UTC(),
    SubjectKeyId: id,
    ExtKeyUsage: []x509.ExtKeyUsage{
        x509.ExtKeyUsageAny,
        x509.ExtKeyUsageClientAuth,
    },
}

// create a CertRep message from the original
certRep, err := msg.SignCSR(CAcert, CAkey, tmlp)
if err != nil {
    // handle err
}

// send response back
// w is a http.ResponseWriter
w.Write(certRep.Raw)

Server library

You can import the scep endpoint into another Go project. For an example take a look at cmd/scep/main.go

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micromdm
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