Certificates for PKI

Sign certificate issued by external CA
Request a signing certificate from an external CA
Install an external signing certificate

PKI stands for Public Key Infrastructure. Tokens are documents, cryptographically signed using the X509 standard. In order to work correctly token generation requires a public/private key pair. The public key must be signed in an X509 certificate, and the certificate used to sign it must be available as Certificate Authority (CA) certificate. These files can be generated either using the keystone-manage utility, or externally generated. The files need to be in the locations specified by the top level Identity Service configuration file keystone.conf as specified in the above section. Additionally, the private key should only be readable by the system user that will run the Identity Service.

	Warning
The certificates can be world readable, but the private key cannot be. The private key should only be readable by the account that is going to sign tokens. When generating files with the keystone-manage pki_setup command, your best option is to run as the pki user. If you run nova-manage as root, you can append --keystone-user and --keystone-group parameters to set the username and group keystone is going to run under.

Warning

The certificates can be world readable, but the private key cannot be. The private key should only be readable by the account that is going to sign tokens. When generating files with the keystone-manage pki_setup command, your best option is to run as the pki user. If you run nova-manage as root, you can append --keystone-user and --keystone-group parameters to set the username and group keystone is going to run under.

The values that specify where to read the certificates are under the [signing] section of the configuration file. The configuration values are:

token_format - Determines the algorithm used to generate tokens. Can be either UUID or PKI. Defaults to PKI.
certfile - Location of certificate used to verify tokens. Default is /etc/keystone/ssl/certs/signing_cert.pem.
keyfile - Location of private key used to sign tokens. Default is /etc/keystone/ssl/private/signing_key.pem.
ca_certs - Location of certificate for the authority that issued the above certificate. Default is /etc/keystone/ssl/certs/ca.pem.
key_size - Default is 1024.
valid_days - Default is 3650.
ca_password - Password required to read the ca_file. Default is None.

If token_format=UUID, a typical token looks like 53f7f6ef0cc344b5be706bcc8b1479e1. If token_format=PKI, a typical token is a much longer string, such as:

MIIKtgYJKoZIhvcNAQcCoIIKpzCCCqMCAQExCTAHBgUrDgMCGjCCCY8GCSqGSIb3DQEHAaCCCYAEggl8eyJhY2Nlc3MiOiB7InRva2VuIjogeyJpc3N1ZWRfYXQiOiAiMjAxMy0wNS0z
MFQxNTo1MjowNi43MzMxOTgiLCAiZXhwaXJlcyI6ICIyMDEzLTA1LTMxVDE1OjUyOjA2WiIsICJpZCI6ICJwbGFjZWhvbGRlciIsICJ0ZW5hbnQiOiB7ImRlc2NyaXB0aW9uIjogbnVs
bCwgImVuYWJsZWQiOiB0cnVlLCAiaWQiOiAiYzJjNTliNGQzZDI4NGQ4ZmEwOWYxNjljYjE4MDBlMDYiLCAibmFtZSI6ICJkZW1vIn19LCAic2VydmljZUNhdGFsb2ciOiBbeyJlbmRw
b2ludHMiOiBbeyJhZG1pblVSTCI6ICJodHRwOi8vMTkyLjE2OC4yNy4xMDA6ODc3NC92Mi9jMmM1OWI0ZDNkMjg0ZDhmYTA5ZjE2OWNiMTgwMGUwNiIsICJyZWdpb24iOiAiUmVnaW9u
T25lIiwgImludGVybmFsVVJMIjogImh0dHA6Ly8xOTIuMTY4LjI3LjEwMDo4Nzc0L3YyL2MyYzU5YjRkM2QyODRkOGZhMDlmMTY5Y2IxODAwZTA2IiwgImlkIjogIjFmYjMzYmM5M2Y5
ODRhNGNhZTk3MmViNzcwOTgzZTJlIiwgInB1YmxpY1VSTCI6ICJodHRwOi8vMTkyLjE2OC4yNy4xMDA6ODc3NC92Mi9jMmM1OWI0ZDNkMjg0ZDhmYTA5ZjE2OWNiMTgwMGUwNiJ9XSwg
ImVuZHBvaW50c19saW5rcyI6IFtdLCAidHlwZSI6ICJjb21wdXRlIiwgIm5hbWUiOiAibm92YSJ9LCB7ImVuZHBvaW50cyI6IFt7ImFkbWluVVJMIjogImh0dHA6Ly8xOTIuMTY4LjI3
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MGU2YWNlNDU4NjZmMzAiLCAicHVibGljVVJMIjogImh0dHA6Ly8xOTIuMTY4LjI3LjEwMDozMzMzIn1dLCAiZW5kcG9pbnRzX2xpbmtzIjogW10sICJ0eXBlIjogInMzIiwgIm5hbWUi
OiAiczMifSwgeyJlbmRwb2ludHMiOiBbeyJhZG1pblVSTCI6ICJodHRwOi8vMTkyLjE2OC4yNy4xMDA6OTI5MiIsICJyZWdpb24iOiAiUmVnaW9uT25lIiwgImludGVybmFsVVJMIjog
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MDA6OTI5MiJ9XSwgImVuZHBvaW50c19saW5rcyI6IFtdLCAidHlwZSI6ICJpbWFnZSIsICJuYW1lIjogImdsYW5jZSJ9LCB7ImVuZHBvaW50cyI6IFt7ImFkbWluVVJMIjogImh0dHA6
Ly8xOTIuMTY4LjI3LjEwMDo4Nzc2L3YxL2MyYzU5YjRkM2QyODRkOGZhMDlmMTY5Y2IxODAwZTA2IiwgInJlZ2lvbiI6ICJSZWdpb25PbmUiLCAiaW50ZXJuYWxVUkwiOiAiaHR0cDov
LzE5Mi4xNjguMjcuMTAwOjg3NzYvdjEvYzJjNTliNGQzZDI4NGQ4ZmEwOWYxNjljYjE4MDBlMDYiLCAiaWQiOiAiMzQ3ZWQ2ZThjMjkxNGU1MGFlMmJiNjA2YWQxNDdjNTQiLCAicHVi
bGljVVJMIjogImh0dHA6Ly8xOTIuMTY4LjI3LjEwMDo4Nzc2L3YxL2MyYzU5YjRkM2QyODRkOGZhMDlmMTY5Y2IxODAwZTA2In1dLCAiZW5kcG9pbnRzX2xpbmtzIjogW10sICJ0eXBl
IjogInZvbHVtZSIsICJuYW1lIjogImNpbmRlciJ9LCB7ImVuZHBvaW50cyI6IFt7ImFkbWluVVJMIjogImh0dHA6Ly8xOTIuMTY4LjI3LjEwMDo4NzczL3NlcnZpY2VzL0FkbWluIiwg
InJlZ2lvbiI6ICJSZWdpb25PbmUiLCAiaW50ZXJuYWxVUkwiOiAiaHR0cDovLzE5Mi4xNjguMjcuMTAwOjg3NzMvc2VydmljZXMvQ2xvdWQiLCAiaWQiOiAiMmIwZGMyYjNlY2U4NGJj
YWE1NDAzMDMzNzI5YzY3MjIiLCAicHVibGljVVJMIjogImh0dHA6Ly8xOTIuMTY4LjI3LjEwMDo4NzczL3NlcnZpY2VzL0Nsb3VkIn1dLCAiZW5kcG9pbnRzX2xpbmtzIjogW10sICJ0
eXBlIjogImVjMiIsICJuYW1lIjogImVjMiJ9LCB7ImVuZHBvaW50cyI6IFt7ImFkbWluVVJMIjogImh0dHA6Ly8xOTIuMTY4LjI3LjEwMDozNTM1Ny92Mi4wIiwgInJlZ2lvbiI6ICJS
ZWdpb25PbmUiLCAiaW50ZXJuYWxVUkwiOiAiaHR0cDovLzE5Mi4xNjguMjcuMTAwOjUwMDAvdjIuMCIsICJpZCI6ICJiNTY2Y2JlZjA2NjQ0ZmY2OWMyOTMxNzY2Yjc5MTIyOSIsICJw
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SrWY8lF3HrTcJT23sZIleg==

Sign certificate issued by external CA

You can use a signing certificate issued by an external CA instead of generated by keystone-manage. However, a certificate issued by an external CA must satisfy the following conditions:

all certificate and key files must be in Privacy Enhanced Mail (PEM) format
private key files must not be protected by a password

When using signing certificate issued by an external CA, you do not need to specify key_size, valid_days, and ca_password as they will be ignored.

The basic workflow for using a signing certificate issued by an external CA involves:

Request Signing Certificate from External CA
Convert certificate and private key to PEM if needed
Install External Signing Certificate

Request a signing certificate from an external CA

One way to request a signing certificate from an external CA is to first generate a PKCS #10 Certificate Request Syntax (CRS) using OpenSSL CLI.

Create a certificate request configuration file. For example, create the cert_req.conf file, as follows:

[ req ]
default_bits            = 1024
default_keyfile         = keystonekey.pem
default_md              = sha1

prompt                  = no
distinguished_name      = distinguished_name

[ distinguished_name ]
countryName             = US
stateOrProvinceName     = CA
localityName            = Sunnyvale
organizationName        = OpenStack
organizationalUnitName  = Keystone
commonName              = Keystone Signing
emailAddress            = [email protected]

Then generate a CRS with OpenSSL CLI. Do not encrypt the generated private key. Must use the -nodes option.

For example:

$ openssl req -newkey rsa:1024 -keyout signing_key.pem -keyform PEM \
  -out signing_cert_req.pem -outform PEM -config cert_req.conf -nodes

If everything is successful, you should end up with signing_cert_req.pem and signing_key.pem. Send signing_cert_req.pem to your CA to request a token signing certificate and make sure to ask the certificate to be in PEM format. Also, make sure your trusted CA certificate chain is also in PEM format.

Install an external signing certificate

Assuming you have the following already:

signing_cert.pem - (Keystone token) signing certificate in PEM format
signing_key.pem - corresponding (non-encrypted) private key in PEM format
cacert.pem - trust CA certificate chain in PEM format

Copy the above to your certificate directory. For example:

# mkdir -p /etc/keystone/ssl/certs
# cp signing_cert.pem /etc/keystone/ssl/certs/
# cp signing_key.pem /etc/keystone/ssl/certs/
# cp cacert.pem /etc/keystone/ssl/certs/
# chmod -R 700 /etc/keystone/ssl/certs

	Note
	Make sure the certificate directory is only accessible by root.

If your certificate directory path is different from the default /etc/keystone/ssl/certs, make sure it is reflected in the [signing] section of the configuration file.

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