EST

ENTERPRISE  This is an EJBCA Enterprise feature.

The Enrollment over Secure Transport (EST) is a cryptographic protocol that describes an X.509 certificate management protocol targeting public key infrastructure (PKI) clients that need to acquire client certificates and associated certificate authority (CA) certificates.

Introduction

EJBCA supports the EST protocol as defined in RFC7030 as of EJBCA version 6.11.

EST provides a basic protocol for certificate enrollment and management similar to SCEP, with the following distinct advantages:

  • While SCEP communicates over HTTP and ensures integrity by wrapping the payload in a cryptographic envelope, EST requests are always over TLS and thus inherently secure.
  • EST supports ECC, while SCEP does not.
  • While SCEP requires a shared secret to authenticate CSRs, in EST authentication is implicit when negotiating the TLS connection.
  • Certificate renewal is an integral part of EST, while in SCEP it is rather an afterthought.
  • EST supports server-side key generation, which SCEP does not (currently not supported in EJBCA).

Supported Operations

The following operations in EST are supported:

NameDescription
cacerts

A GET request that returns a cert-only pkcs#7 blob containing the CA certificate (and possible chain) for the given alias that is used to issuing certificates via enrollment operation. This operation requires no authentication.

simpleenroll

A POST request with a CSR in PKCS#10 format and Base64 encoded to be signed by the specified CA for the given alias. May require an existing client certificate for authentication and/or HTTP Basic authentication via username and password.

The end entity username will be set according to the specified RA name generation scheme. If there is no existing end entity with the generated username, a new end entity will be created. If an end entity with the specified username already exists, it is treated as a renewal: a new certificate is issued for the existing end entity (as long as no settings block this behavior: e.g. Enforce Unique DN or Enforce Unique Public Keys).

simplereenrollA POST request with a CSR in PKCS#10 format and Base64 encoded to be signed by the specified CA for the given alias. Requires authenticating with the original certificate, which has to be valid (to establish a TLS connection) and not revoked.

A request with an unsupported operation will result in an HTTP not found (404) response from the server.

EST Configuration

Access

The EJBCA EST implementation uses the Well-Known Uniform Resource Identifiers (URIs) definition codified in RFC 5785.

Like SCEP and CMP, EJBCA supports using EST for multiple CAs by the use of aliases. Each alias is then accessible using:

$ /.well-known/est/<alias>/<operation>

When an alias with the name est is configured, this alias is available over the default EST URL, which is the URL used by the estclient, see Testing.

/.well-known/est/<operation>

A request with an unknown alias will result in an HTTP bad request (400) response from the server.

Configuring Aliases

The following displays the EST alias configuration screen.

The following lists available EST alias configuration options.

ValueDescription
RA Name Generation SchemeDN: Will take a part of the request DN, and use it as the username (use the list to choose which parts). Several DN attributes can be specified to have fall-back. For example: UID;SN;CN. First try UID. If it does not exist try SN, etc.
RANDOM: Will generate a 12 character long random username.
FIXED: Enter the DN attributes manually as a semicolon delimited String (e.g. CN;UID;SN), instead of adding the values via the Add button, when the DN radio button is selected.
USERNAME: Use entire request DN as username.
RA Name Generation PrefixSpecify a prefix to the generated username. '${RANDOM}' can be used to have a 10 random chars as prefix.
RA Name Generation PostfixSpecify a postfix to the generated username. '${RANDOM}' can be used to have a 10 random chars as postfix.
Default CAThe CA that this alias will issue certificate from.
End Entity ProfileThe End Entity Profile that enrolling end entities will have applied to them. This defines the required DN and altName naming fields.
Certificate ProfileThe Certificate Profile that enrolling end entities will have applied to them. This controls the certificate type, that is, key usage and other extensions.
Require Client CertificateSpecifies if a client certificate is required to enroll. The client certificate does not need to be known by EJBCA (if the option web.reqcertindb in conf/web.properties is set to false), but the issuing CA is. The client certificate needs to belong to a Role with full RA rights.
Client username/passwordSets a username and password to enroll. The username will be given full RA rights. If a client certificate is required, both client certificate and username/password will be checked for initial enrollment. For Renewal (re-enroll) username and password are never required, but client certificate is always required.
Certificate Renewal with Same KeysIf Allow is selected, a re-enrollment request may be performed for the same public key as before. Note that client certificate is always required for renewal, while username/password is never required, regardless of the settings above.

Testing

Clone libest from Cisco and build according to instructions:

$ cd examples/client
$ # via environment specify the initial CA certificate to use for verifying TLS connection.
$ cp <path to server cert> server.pem
$ export EST_OPENSSL_CACERT=server.pem
$ # Where to save certs
$ mkdir certs
$ # Optionally get new CA certificates
$ ./estclient -g -s <ip or hostname to EJBCA> -p 8442 -o certs --pem-output
$ # certs should now contain a cacert-0-0.pem file
$ # enroll with CA. publicCert.pem and privetKey.pem are the TLS client cert I wish to use for auth. RequestDN will be 'CN=myclient'
$ ./estclient -e -s <ip or hostname to EJBCA> -p 8443 -o certs -c publicCert.pem -k privateKey.pem -u estadmin -h foo123 --pem-output --common-name myclient
$ # certs will now contain a cert-0-0.pem and key-x-x.pem
$ # client cert is about to expire, reenroll, requires client certificate authentication to the server
$ ./estclient -r -s <ip or hostname to EJBCA> -p 8443 -o tmp -c tmp/cert-0-0.pem -k tmp/key-x-x.pem --pem-output
$ # certs should now contain an updated cert-0-0.pem	

You can also test access to EST URLs using curl commands.

Here is a full work-flow example using CURL, where initial enrollment uses username/password EST authentication, and re-enroll using the existing client certificate.

# Get CA certificates
curl https://<hostname to EJBCA>:8442/.well-known/est/cacerts -o cacerts.p7 --cacert ManagementCA.cacert.pem
# Generate a key and CSR for a "device"
openssl req -nodes -newkey rsa:2048 -keyout device.key -out device.csr -outform DER -subj "/CN=123456789"
openssl base64 -in device.csr -out device.b64 -e
# Make initial enrollment, using EST password authentication (client certificate is also possible)
curl -v --cacert ManagementCA.cacert.pem --user estadmin:foo123 --data @device.b64 -o device-p7.b64 -H "Content-Type: application/pkcs10" \
-H "Content-Transfer-Encoding: base64" https://<hostname to EJBCA>:8442/.well-known/est/simpleenroll
# Convert the response into a PEM encoded certificate
openssl base64 -in device-p7.b64 -out device-p7.der -d
openssl pkcs7 -inform DER -in device-p7.der -print_certs -out device-cert.pem
# Generate a new key and CSR for the device, to renew with
openssl req -nodes -newkey rsa:2048 -keyout device-new.key -out device-new.csr -outform DER -subj "/CN=123456789"
openssl base64 -in device-new.csr -out device-new.b64 -e
# Re-enroll by the device, authenticating with the existing key/certificate
curl -v --cacert ManagementCA.cacert.pem --key device.key --cert device-cert.pem --data @device-new.b64 -o device-new-p7.b64 -H "Content-Type: application/pkcs10" \
-H "Content-Transfer-Encoding: base64" https://<hostname to EJBCA>:8443/.well-known/est/simplereenroll
# Convert the response into a PEM encoded certificate
openssl base64 -in device-new-p7.b64 -out device-new-p7.der -d
openssl pkcs7 -inform DER -in device-new-p7.der -print_certs -out device-new-cert.pem

ManagementCA.cacert.pem is the Root CA certificate of the CA chain that issued the TLS server cert and needs to be configured with curl in order for the TLS connection to be established. ManagementCA is the name in a default EJBCA installation and the cert can be downloaded from the CA UI or RA UI. The examples above use port 8442 for TLS with server authentication, and port 8443 for TLS with both client and server authentication (when using a client authentication certificate and private key). The standard TLS port, 443, is used when running an Apache proxy in front or EJBCA, such as is the case with an EJBCA Enterprise Cloud instance or a PrimeKey PKI Appliance. For EJBCA Enterprise Cloud instances or the PrimeKey PKI Appliance, port 443 will work for calls with or without client certificate authentication.

You can also authenticate as EST admin using a client certificate. The command is slightly different, using certificate authentication in addition to the username/password:

# Enroll
curl -v --cacert ManagementCA.cacert.pem --user estadmin:foo123 --cert ra-cert.pem --key ra-key.pem --data @device.b64 -o device-p7.b64 -H "Content-Type: application/pkcs10" \
-H "Content-Transfer-Encoding: base64" https://<hostname to EJBCA>/.well-known/est/simpleenroll
# Re-enroll
curl -v --cacert ManagementCA.cacert.pem --key device.key --cert device-cert.pem --data @device-new.b64 -o device-new-p7.b64 -H "Content-Type: application/pkcs10" -H "Content-Transfer-Encoding: base64" https://<hostname to EJBCA>/.well-known/est/simplereenroll

Workflow Example

Example enrollment, where an RA gets CA certificate first and then gets a client certificate, using username/password authentication (the EST client acts as an RA). Next, the client performs a renewal, authenticating with the client certificate issued previously.

EST configuration is an EST alias with the name est and the following settings:

Setting

Value

Default CA

EST CA

End Entity Profile

EST EE Profile (with only CN required DN attribute)

Certificate Profile

Profile Default

Require Client Certificate

false

Client Username

estadmin

Client Password

foo123

Certificate Renewal with Same Keys

false

Download the CA certificate of the EJBCA TLS connection (usually the default is Management CA), and set the environment variable needed for estclient:

export EST_OPENSSL_CACERT=/tmp/ManagementCA.cacert.pem

Run the following estclient commands to generate a key and get a certificate from the CA:

$ mkdir certs

# Get CA certificate, by "RA:
$ ./estclient -g -s 127.0.0.1 -p 8442 -o certs --pem-output

# Inspect the fetched CA certificate 
$ openssl x509 -in certs/cacert-0-0.pem -text -noout

# Get client certificate, by "RA", authenticated with username/password
$ ./estclient -e -s 127.0.0.1 -p 8442 -o certs -u estadmin -h foo123 --pem-output --common-name myclient

# Inspect the fetched client certificate 
$ openssl x509 -in certs/cert-0-0.pem -text -noout

# Re-enroll, directly by the client when certificate is about to expire, using the old client cert to authenticate with:
$ ./estclient -r -s 127.0.0.1 -p 8443 -o certs -c certs/cert-0-0.pem -k certs/key-x-x.pem -u estadmin -h foo123 --pem-output

# Inspect the new, renewed, client certificate  
$ openssl x509 -in certs/cert-0-0.pem -text -noout

# Revoke the clients certificates by going to CA UI and using Search End Entities to find the end entity and revoke certificates.
# Try to re-enroll again, which will not work with a revoked client certificates.
$ ./estclient -r -s 127.0.0.1 -p 8443 -o certs -c certs/cert-0-0.pem -k certs/key-x-x.pem --pem-output

# Enroll with an EC key. First we have to generate the key, a Prime256v1 key on this case, and then use this key for enrollment.
openssl ecparam -name prime256v1 -genkey -noout -out prime256v1-key.pem
./estclient -e -s 127.0.0.1 -p 8442 -o certs -u estadmin -h foo123 --pem-output --common-name myclient -x prime256v1-key.pem
$ openssl x509 -in certs/cert-0-0.pem -text -noout

# Re-enroll, also with EC, using the same key (using the same key can be dissalowed in the EST alias).
./estclient -r -s 127.0.0.1 -p 8443 -o certs -c certs/cert-0-0.pem -k prime256v1-key.pem --pem-output -x prime256v1-key.pem
$ openssl x509 -in certs/cert-0-0.pem -text -noout