Is it possible, in general, for a server to require both client certificate authentication and BASIC authentication?
For example, an intranet site of some sort, which requires :
The machine to have a specific certificate installed (client cert authentication), AND
A valid user to log in (basic authentication)
NOTE: this question isn't about a server supporting one or the other, but both together (as in the requester must authenticate both ways)
Yes, it is possible to have both. The client certificate will be verified during the TLS handshake while basic authentication will be done at the HTTP level, i.e. inside the TLS connection after the TLS handshake is done and the client certificate checked.
Related
In the TLS handshake process, the Certificate Verify message will follow the Client Key Exchange message after the server requested a client certificate. The Certificate Verify contains a digital signature computed over all previous handshake messages including the type and length fields of the handshake messages. This process allows the client to prove that it owns the private key of the client certificate it sends to the server.
The idea came from a practical problem. There is an mTLS enabled server that conducts different action policies based on the client certificate received, for example, different welcome pages for different client certificates. If a layer-7 reverse proxy service like the load balancer is placed in front of the proxied server which also requires decrypting the TLS traffic. The proxied server can only get the client certificate information from the HTTP header (for example, set proxy_set_header with $ssl_client_cert variable in NGINX) which requires modifying the logic of the server.
A simple but very troublesome solution is the reverse proxy service stores all the client certificates and their private keys. The reverse proxy service will use the same client certificate it received during the mTLS handshake process to establish the mTLS connection with the proxied server.
Since the reverse proxy service can choose whether to trust the client or not with its own implementation, it is possible to forge the Certificate Verify message by asking the client to send a second Certificate Verify signature when the proxied server needs the reverse proxy service to do so (I know it's like a man-in-the-middle attack)?
I could find any quick answer on google. Most probably the answer lies somewhere in RFC docs on http or https however I just couldn't (too time consuming ) get those information.
So here is the question:
Is the content of a webpage served through HTTP signed digitally by the server ? Same question for HTTPS.
If yes, how does it work correctly when using a proxy ? In my opinion the proxy could tamper the data, sign the tampered data with it's own private key, and claim that the corresponding proxy's public key is actually the genuine public key of the original server ? I am assuming that the client can't check the original server's public key, because there is a proxy which could lie.
I am sorry if this is a dump question and easy searchable on the internet, but every answer I found posed some doubts to me.
Thanks for your help :)
Content sent via HTTPS is encrypted, clients verify the authenticity of the host certificates with whom they are communicating. The server uses a TLS/SSL key/certificate which is signed by certificate authorities (CA) The CAs make sure that they only sign the certificates of the rightful owners of a domain. The certificates of the CAs them-self are installed in you browser/OS. By using these pre-installed certificates, the browser can check if the key used by the remote server is signed by a trusted CA.
A man-in-the-middle does not have the original key, nor another key signed by a CA for the domain in question. Therefore, a man-in-the-middle cannot modify the content without breaking HTTPS.
On the other hand, if you want to use a proxy to cache requests, the proxy can terminate the HTTPS connections. This means the proxy has its own connection to the server and verifies the certificates. In order to secure the connection to the client, the proxy acts as a CA and uses a HTTPS connection with self-signed certificates. To avoid that your browser complains about an insecure connection, you need to install the proxies own CA certificate.
HTTP content is not signed and can be tampered with.
Edit 2018-06-15:
I wasn't really precise with the term "signed" here. The server does not actually sign the content it sends. This means if you store the responses from the server, you cannot prove that they came from that server, in other words: standard TLS dose not provide non-repudiation. However, the authenticity of the server is established during the handshake. The client encrypts a master-key with the servers public key. Only servers in possession of the private key can decrypt the master-key and derive session keys from them.
CAs, on the other hand, actually sign the certificates. A CA cannot validly deny that it signed for the authenticity of a server certificate.
I use the same certificate both for client and service authentication on Wcf with message security. Does it cause any serious vulnerability?
You don't want to have the full certification on both the server and client for security reasons. Have a look at this Server / Client Certs
Can client certificates be used for authentication without HTTPS, only over HTTP on Windows IIS platform with ASP.NET ?
I need to authenticate a client using a digital certificate and i can't use HTTPS.
No you can't, at least if the client is a web-browser. Moreover, it doesn't have any sense.
What makes https more secure than http?
The short answer is that https communication between your browser and the server are encrypted. While http traffic is sent in plain text. This means that anyone who can listen to the traffic can read it - this would include usernames and passwords). It also verifies the server to which you are connecting.
That it is encrypted. Read: en.wikipedia.org/wiki/HTTP_Secure
Anything not over HTTPS can be read by anyone snooping on your network.
Im quoting:
Hypertext Transfer Protocol Secure (HTTPS) is a combination of the Hypertext Transfer Protocol with the SSL/TLS protocol to provide encryption and secure identification of the server.
More information on TLS:
The TLS protocol allows client/server applications to communicate across a network in a way designed to prevent eavesdropping and tampering. TLS provides endpoint authentication and communications confidentiality over the Internet using cryptography. TLS provides RSA security with 1024 and 2048 bit strengths.
Also, HTTPS verifies that the site is who it claims to be, if the certificates are correct (signed by a known CA).
All traffic is encrypted. No one on your network can see what is going on (except for knowing where those packets are going to).
The identity of the remote server can be verified using certificates. So you also know that it really is your bank that you are talking to.
Optionally (and not in wide-spread use), the identity of the client can also be verified using certificates. This would allow for secure login to a site using chip cards instead of (or in addition to) passwords.
I want to be really pedantic, as I'm a security nerd :)
HTTPS uses SSL, and it's IETF-ratified cousin, TLS. SSL/TLS can offer four security services:
1) server authentication
2) channel encryption
3) channel tamper detection
4) client authentication
Usually you'll get server auth for free, but only if the host name and the common name in the server's SSL/TLS certificate match. If they don't match your browser will warn you. You usually get the channel defenses for free too, but that's only because the server and client negotiate to require such defenses. In theory, but rarely in practice, a server and client could agree to not use one or more of the channel defenses.
Finally, client authentication is when the server wants you to present a certificate (actually, to prove you have an associated private key) to verify you are you. Client authentication is rarely used.