Is there any way to explicitly specify the set of cipher suites that you'd like your URLSession client to try and use when establishing a secure connection?
I know that there's the NSExceptionRequiresForwardSecrecy key in the NSAppTransportSecurity dictionary but that doesn't seem to be what I need.
I basically just want to be able to tell the client to notify the server that it is only willing to use the following cipher suites:
TLS_RSA_WITH_RC4_128_SHA,
TLS_RSA_WITH_3DES_EDE_CBC_SHA,
TLS_RSA_WITH_AES_128_CBC_SHA,
TLS_RSA_WITH_AES_256_CBC_SHA,
TLS_RSA_WITH_AES_128_GCM_SHA256,
TLS_RSA_WITH_AES_256_GCM_SHA384,
That way I can decrypt the HTTP/2 traffic that the client and server and communicating with.
As far as I'm aware, there's no way to do this at the NSURLSession level. You can, of course, write code based on the Secure Transport API, but AFAIK there's no easy way to make NSURLSession use a custom underlying socket. (You might be able to use CFHTTPMessage and friends to make it slightly less horrible than writing a full HTTP stack yourself, but it still won't be pretty.)
With that said, if you're using an HTTPS proxy (e.g. Charles Proxy), it should be able to specify which cipher suites are supported and let you MitM the connection without the need for any sort of custom code in the app itself.
If that doesn't meet your needs, I would encourage you to file enhancement requests at bugreport.apple.com and explain what you're trying to do and why. They might be able to suggest some other options.
Related
general questions about the using of *fail_if_no_peer_cert *and *fail_if_no_peer_cert *params in *rabbitmq_management *on windows
if a client calls management API through https, the requests are secured by the certificate which is installed on the server and trusted on the client. actually, it means, this certificate shouldn't be rabbitmq compatible, it can be just http-certificate... is it correct?
in case i want to validate clients as well, i must have these params verify and true? what is the best practice? because i see these params explained in AMPQ settings and never in management
actually my motivation for this questions is just to understand if i need to deal with this issue at all. because setting *fail_if_no_peer_cert *as true makes a lot of things much more complicated. foe example you just can simply open management api plugin in browser, you need deal with client certificate.
I'm trying to use wireshark to decode, view, and ultimately log my own https traffic--response bodies included. According to the wireshark docs, I need provide the file location of the private RSA key used to decode messages. My question is this:
Where on osx is the private rsa key used in https interactions, is this a single key? Many?
Wireshark docs seem to be telling me to make an RSA key. Given that I'm not experienced enough with this topic, messing with system keys because I read a thing on the internet seems like a pit of despair. What should I do?
What I'm really trying to do is log unencrypted https requests/responses with bodies, while listening to web traffic. If there's a better way I'm all ears.
What I'm really trying to do is log unencrypted https requests/responses with bodies, while listening to web traffic. If there's a better way I'm all ears.
Don't mess around with Wireshark for this. The documentation you're reading is outdated; modern TLS cipher suites do not use pure RSA for key exchange. This configuration was only supported by SSL 2.0, which was superseded by SSL 3.0 in 1996, and is no longer supported by any moern browser. Long story short -- it doesn't actually work in practice.
Instead, use a HTTPS proxy server. Several common tools for this purpose are:
mitmproxy
Charles Proxy (commercial)
fiddler
Many of these tools will also allow you to alter the contents of an HTTPS session, which is certainly not something that Wireshark will do.
I am using a third party (OS X) tool to help me process OFX financial data. It works, but I am interested in knowing what exactly is going on behind the scenes to make it work (the structure of the HTTP requests).
I setup Charles as an SSL proxy for all traffic in hopes that I could observe the requests being made by this tool, but the program runs and Charles gets nothing. No requests show up whatsoever. How is that possible? Is there something I am not understanding about how Charles or other packet sniffing tools work? What are some ways that web requests could be made that wouldn't show up in a tool like Charles?
Charles is not a packet sniffer. It's a proxy. The app initiating the connection has to "voluntarily" use the proxy for the proxy to see anything. If an app uses a high-level networking API like NSURLConnection then it will, by virtue of the frameworks, automatically pick up the system-wide proxy settings and use the proxy. If, instead, the app wrote their networking using low-level socket API, then they will not end up going through the proxy unless they specifically re-implement that functionality.
If you want to see everything, you will need a real promiscuous-mode packet sniffer, which Charles is not. Unfortunately, using a "real" packet sniffer will just show you the gibberish going over the wire for SSL connections, so that's probably not what you want either. If an app has "in-housed" its SSL implementation and is not using a properly configured system-wide proxy, sniffing its traffic unencrypted will be considerably harder (you'll probably have to use a debugger or some other runtime hooking approach.)
I have learned a little about https, but was not clear why it is needed.
What if I encrypt the data using the most powerful algorithms like RSA instead of sending through a HTTPS zone? Can someone explain with a few reasons why we need https?
On the Wikipedia article it says
Technically, it is not a protocol in itself; rather, it is the result
of simply layering the Hypertext Transfer Protocol (HTTP) on top of
the SSL/TLS protocol
On the SSL/TLS article on Wikipeida,
TLS and SSL encrypt the segments of network connections at the
Application Layer for the Transport Layer, using asymmetric
cryptography for key exchange, symmetric encryption for
confidentiality, and message authentication codes for message
integrity.
So the key exchange does use asymmetric cryptography and RSA is an asymmetric cryptography algorithm.
After key exchange has been performed in a secure manner further communication can be done through symmetric cryptographic algorithms. The reasoning behind using both symmetric and asymmetric algorithms can be found here.
What if I encrypt the data using the most powerful algorithms like RSA
instead of sending through a HTTPS zone?
You will have to implement all by yourself, i.e. reinvent the wheel. HTTPS is by default supported in every browser.
Can someone explain with a few reasons why we need https?
Secure communication that is widely supported. If you have in the middle of communication someone with sniffer tool like Wireshark, he/she will be able to see all packets that you and your peer exchange. Try to catch the HTTPS communication, you won't be able to see anything meaningful in the body of the request.
You could indeed encrypt the data by yourself, but you will face a big problem: The encrypting code must be available on the server as well as on the client (normally the browser).
Implementing the encryption on the server can be done securely. On the client side you can either install a software (plugin), or you can send JavaScript to the client. The problem is: how do you get the encrypting code to the client? Everybody evesdropping, will get the javascript code as well, so he can do the same things as the client will be able to do.
Instead of forcing the user to install a plugin, you can use the built-in support for SSL, every browser understands this protocol already. You could think of it, as an already installed plugin for encryption.
I'm trying to develop a XMPP "Proxy" which will be in the middle of a standard Jabber communication.
The schema will be something like this:
Pidgin ---> Proxy <--- eJabberD
|
v
Console
The purpose of this proxy is to log all the stanzas which go over the wire. IMHO, this is very convenient when you're developing XMPP based solutions.
I'm doing this with EventMachine and Ruby, and the main problem is to know how to decypher the traffic after the TLS/SASL handshake.
Before the starttls, all works perfectly, the server and client can talk between them, but when the tls handshake begins, although it works, it is impossible to dump the clear content as all of the traffic is encrypted.
I'm not an expert in TLS/SASL thing, so I don't know which is the best approach to do this. I think one way to achieve this, should be to grab the certificate in the handshake and use it to decypher the content as it goes throught the proxy.
Thanks!
If you could do what you say (grab the certificate on the wire and use it to decrypt), then TLS would be pretty worthless. This is one of the primary attacks TLS exists to prevent.
If the server will allow it, just don't send starttls. This is not required by spec. If starttls is required by your server, then you can configure it to use a null cipher, which will leave the traffic unencrypted. Not all servers will support that of course.
You can man-in-the-middle the starttls. Respond with your own tunnel to the client, and send a separate starttls negotiation to the server. This should generate certificate warnings on the client, but since you control the client you can tell it to accept the certificate anyway.
If you control the server, you can use the private key from it to decrypt the traffic. I'm not aware with any off-the-shelf code to do that easily, but it's writable.