Exchange of digital certificates in a client-proxy-server network configuration
Various techniques are described to authenticate the identity of a proxy in a client-proxy-server configuration. The configuration may have a client-side and a server-side SSL session. In the server-side session, if the proxy has access to the private keys of the client, the proxy may select a client certificate from a collection of client certificates and send the selected certificate to the server to satisfy a client authentication request of the server. If the proxy does not have access to the private keys, the proxy may instead send an emulated client certificate to the server. Further, the client certificate received from the client may be embedded within the emulated client certificate so as to allow the server to directly authenticate the client, in addition to the proxy. An emulated client certificate chain may be formed instead of an emulated client certificate. Similar techniques may be applied to the client-side session.
1. A method for providing a client certificate from a proxy to a server, the proxy communicatively coupled between a client and the server, the method comprising:
configuring at the proxy a collection of one or more client certificates and one or more client private keys, each client certificate corresponding to a client private key;
defining a policy at the proxy which selects one of the client certificates based on information associated with an identity of the client;
in response to a request from the server to the proxy to authenticate the identity of the client, selecting one of the client certificates based on the defined policy; and
transmitting the selected client certificate from the proxy to the server.
2. The method of claim 1 , wherein one of the client certificates is selected further based on one or more of a group that the client belongs to, a URL of the server, a network address of the server, and field values of a server certificate.
3. The method of claim 1 , wherein one of the client certificates is selected further based on a user group associated with the client.
4. The method of claim 1 , further comprising securely sending one or more client certificates and their associated private keys from the client to the proxy.
5. A method for providing a client certificate from a proxy to a server, the proxy communicatively coupled between a client and the server, the method comprising:
authenticating an identity of the client at the proxy;
configuring at the proxy a collection of one or more client certificates and one or more client private keys, each client certificate corresponding to a client private key;
defining a policy at the proxy which selects one of the client certificates based on information associated with the identity of the client;
receiving at the proxy a request from the client to connect to the server;
transmitting a request from the proxy to the server to establish a connection between the proxy and the server;
providing from the proxy to the client an emulated server certificate to allow man-in-the-middle interception;
in response to a request from the server to authenticate the identity of the client, selecting one of the client certificates based on the defined policy; and
transmitting the selected client certificate from the proxy to the server.
6. A method for providing an emulated server certificate from a proxy to a client, the proxy communicatively coupled between the client and a server, the method comprising:
in response to a request from the client to the proxy to authenticate an identity of the server, sending a request from the proxy to the server for a server certificate, which binds a public key of the server with the identity of the server;
generating a key pair having a private key and public key;
generating an emulated server certificate based on the server certificate, the emulated server certificate containing the public key generated at the proxy instead of the public key of the server;
embedding the server certificate in a field within the emulated server certificate;
signing the emulated server certificate; and
transmitting the emulated server certificate from the proxy to the client.
7. The method of claim 6 , wherein the server certificate is embedded in an nsComment field of the emulated server certificate.
8. The method of claim 7 , further comprising the client verifying an identity of the proxy via the emulated server certificate and verifying the identity of the server via the embedded server certificate.
9. A method for providing an emulated client certificate from a proxy to a server, the proxy communicatively coupled between a client and the server, the method comprising:
in response to a request from the server to the proxy to authenticate an identity of the client, sending a request from the proxy to the client for a client certificate, which binds a public key of the client with the identity of the client;
generating a key pair having a private key and public key;
generating an emulated client certificate based on the client certificate, the emulated client certificate containing the public key generated at the proxy instead of the public key of the client;
embedding the client certificate in a field within the emulated client certificate;
signing the emulated client certificate; and
transmitting the emulated client certificate from the proxy to the server.
10. The method of claim 9 , wherein the client certificate is embedded in an nsComment field of the emulated client certificate.
11. The method of claim 9 , further comprising the server verifying an identity of the proxy via the emulated client certificate and verifying the identity of the client via the embedded client certificate.