![]() ![]() This means that someone who intercepts the traffic can not read it since it's encrypted with the server's certificate. ![]() Usually when a device and server communicate via ssl/tls, the request and responses are encrypted using the server's certificate. That's why you have to install it's certificate on the device you are using. What Charles does is basically a Man-in-the-middle attack. It's a long answer and I hope that can answer your concern. Since Proxyman can see the Request/Response in plain text, it can display on the app or performs few debugging tools to modify the data, such as Map Local, Scripting, Breakpoint, etc. The client receives the Response and works as normal. This step is really easy because the server's certificate is signed by a well-known CA certificate.Īs soon as Proxyman receives a Response, Proxyman reads it and sends it back to the client. Proxyman now acts as a Client and connects to the server. Proxyman now acts as a Server, so Proxyman can decrypt the read the HTTPS Request in plain text. Common Name and DNS name must equal the HostĪt this point, the SSL Handshake is complete, and the client starts sending the HTTPS Request.Because the CA Certificate is trusted in their system and it passes some basic evaluation, such as: The client will verify the leaf certificate and it's passed. Proxyman server sends the leaf certificate back to the client.Ĥ.5. This step can be implemented by using OpenSSL or BoringSSL library.Ĥ.4. If it's a macOS/iOS app, make sure the certificate is complied with a new security requirement from Apple. It's important to construct the same certificate that has the same information from the server. Proxyman starts generating a leaf certificate by using Proxyman CA Certificate. Some clients can detect the missing data in the leaf certificate and reject it.Ĥ.3. It just generates a basic leaf certificate. Proxyman parses the certificate and gets all certificate information, such as Org, Name, Common Name, Subject Alternative Name (DNS and IP Address), etcįrom what I know, Charles Proxy doesn't perform this step. Proxyman extracts the Host key in the previous CONNECT request and starts fetching the actual certificate server.Ĥ.2. For macOS: Install & trust in System Keychain.appĤ.1.In order to make it successful, you have to install and trust Proxyman/Charles CA Certificate, which is a self-signed certificate. Your app and Proxyman server would perform SSL Handshake. Proxyman accepts it and returns 200 OK Status. The first request is a CONNECT request to Proxyman/Charles Server. Guideline: Īs soon as the client (macOS) or iOS app (iOS devices) makes an HTTPS request with a Proxy Config. If it's an iPhone, you have to manually set a Proxy config in the Setting app. It's essential to make sure all traffic will go through Proxyman/Charles server. It also overrides the HTTP/HTTPS Proxy in Network -> Wifi -> Advanced -> Proxies tab. When you start Proxyman/Charles, it will open a server at IP=127.0.0.1, port 9090, or 8080.I'm a creator of Proxyman, which is a macOS web debugging proxy like Charles Proxy, so I might have the insight and experience to answer your questions. It would be really great if someone could contribute to this answer! This is how I think all the SSL proxying works with Charles. Your application won't know how to decrypt it unless you give him the public key of the certificate (this is done by "installing" the certificate on your application/browser/android device/etc.). To do so, Charles uses his own certificate (public + private key pair), encrypts your data and sends it back to your application.įinally, your application receives this data encrypted by Charles. ![]() So at this moment Charles has the response from your https request unencrypted, and this must be passed to your application, but your application is expecting encrypted data, so Charles has to encrypt it again so your application (i.e.: your browser) doesn't complain about an uncrypted https response. ![]() At this moment, Charles connects to the https site by using the site's public key to encrypt and decrypt data, as if it was a regular browser or application. The point is that when your application performs an HTTPS request to a site firstly it has to go through the Charles Proxy (don't forget it is a proxy!). In fact, it would be great if someone from the Charles Proxy team could help us on this. Ok, what I'm going to post here is just how I think SSL proxying with Charles works, but I don't have any solid base to ensure my answer is correct. ![]()
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