PKI Components in Junos OS

PKI Management and Implementation

The minimum PKI elements required for certificate-based authentication in Junos OS are:

• CA certificates and authority configuration.

• Local certificates including the device’s identity (example: IKE ID type and value) and private and public keys

• Certificate validation through a CRL.

Junos OS supports three different types of PKI objects:

Internet Key Exchange

The procedure for digitally signing messages sent between two participants in an Internet Key Exchange (IKE) session is similar to digital certificate verification, with the following differences:

• Instead of making a digest from the CA certificate, the sender makes it from the data in the IP packet payload.

• Instead of using the CA's public-private key pair, the participants use the sender's public-private key pair.

Trusted CA Group

A Certificate Authority (CA) is a trusted third party responsible for issuing and revoking certificates. You can group multiple CAs (CA profiles) in one trusted CA group for a given topology. These certificates are used to establish connection between two endpoints. To establish IKE or IPsec, both the endpoints must trust the same CA. If either of the endpoints are unable to validate the certificate using their respective trusted CA (ca-profile) or trusted CA group, the connection is not established.

For example, there are two endpoints, endpoint A and endpoint B are trying to establish a secure connection. When endpoint B presents it’s certificate to endpoint A, the endpoint A will check if the certificate is valid. The CA of the endpoint A verifies the signed certificate that the endpoint B is using to get authorized. When trusted-ca or trusted-ca-group is configured, the device will only use the CA profiles added in this trusted-ca-group or the CA profile configured under trusted-ca to validate the certificate coming from endpoint B. If the certificate is verified as valid, the connection is allowed, else the connection is rejected.

Benefits:

• For any incoming connection request, only the certificate issued by that particular trusted CA of that endpoint gets validated. If not, the authorization will reject establishing the connection.

Cryptographic Key Handling Overview

With cryptographic key handling, persistent keys are stored in the memory of the device without any attempt to alter them. While the internal memory device is not directly accessible to a potential adversary, those who require a second layer of defense can enable special handling for cryptographic keys. When enabled, the cryptographic key handling encrypts keys when not immediately in use, performs error detection when copying a key from one memory location to another, and overwrites the memory location of a key with a random bit pattern when the key is no longer in use. Keys are also protected when they are stored in the flash memory of the device. Enabling cryptographic key handling feature does not cause any externally observable change in the behavior of the device, and the device continues to interoperate with the other devices.

A cryptographic administrator can enable and disable the cryptographic self-test functions; however, the security administrator can modify the behavior of the cryptographic self-test functions such configuring periodic self-tests or selecting a subset of cryptographic self-tests.

The following persistent keys are currently under the management of IKE and PKI:

• IKE preshared keys (IKE PSKs)

• PKI private keys

• Manual VPN keys