Develop Reference

Trust anchor for certification path not found in localhost (Android studio insecure communication)

I'm following this guide for an university project: https://checkmarx.github.io/Kotlin-SCP/m3-insecure-communication/
The attack works properly, but when I change to https i get that error. Googling I've seen that maybe the problem is Android, because the Let's Encrypt SSL certificate works on local so my phone doesn't recognize it as a valid certificate (?)
Perhaps I'm not setting the certificate from Let's Encrypt right. Can someone help?

Trust Anchor not found for Android under proxy connection

I developed a simple Android app using Expo SDK that communicates with my server via HTTPS (using Axios if it matters). I have bought the domain and use a LetsEncrypt certificate configurated in NGINX that has an A+ score in the Qualys SSL Test. The app works well with most of my clients except one that uses it under a network proxy that I don't have access to.
Every time the app tries to request the servers I get the error:
java.security.cert.CertPathValidatorException: Trust anchor for certification path not found.
Which according to this article https://developer.android.com/training/articles/security-ssl?hl=en-us can happen when "The CA that issued the server certificate was unknown", "The server certificate wasn't signed by a CA, but was self signed", "The server configuration is missing an intermediate CA" which is not the case since it works with every other client.
This client uses Android 8.1 and I've already checked in “Encryption & credentials” settings that "DST Root CA X3" (which is the anchor for LetsEncrypt) is listed as a trusted root certificate in the devices.
For test purposes, I also have developed a version of my app that does not use HTTPS and it works fine even under the proxy connection.
Am I missing something here? What else could be causing this problem? Any ideas on how to replicate it? Thank you!

ASP .Net Core with Kestrel implement SSL

i'm facing problem when implementing ssl to my web. My web work as web services for android and ios. All goes very smooth until i implement the SSL certificates, suddenly the android (most of android except samsung) throw this error :
E/ErrorHTTP: java.security.cert.CertPathValidatorException: Trust anchor for certification path not found.
then i google and landed to here :
google says about the error
support the google statement
work around for the error to accept the not valid ssl
it says that mostly happened because of :
The CA that issued the server certificate was unknown
The server certificate wasn't signed by a CA, but was self signed
The server configuration is missing an intermediate CA
Those three options already ruled out, i already check with ssl checker. Its none of those above, it's not unknown, it's not self signed, we're using comodo and the intermediates and root certificates also valid, you can check here : ssl checker for my link,
you can check it by yourself.
And now i'm stuck, the certificate is valid. The certificate also can open in samsung, but somehow fail in some other brand, for example xiao mi. I don't know where to look now, is it the :
the ssl configuration, i need to keep digging, even though it marked as valid in most validator.
make the android code more vulnerable, even some brand can access it, i mean is it because the brand or how ?.
The spec im using :
ASP .Net Core 2.0.
Kestrel.
Comodo certificates.
Native android.
Please help !, thank you.

Android app don't trust SSL certifcate but Chrome do

We have an internal CA server.
We have an Android app that should communicate via https with our webserver, and have generated the required certificates. When we connect to the server through our app, it fails with the current stacktrace:
Caused by: java.security.cert.CertificateException: java.security.cert.CertPathValidatorException: Trust anchor for certification path not found.
But when we browse the server through Android Chrome it works, and we get a green keylock. We have uploaded the certificate on the android device under settings. So it's listed under User certificates.
My question is: Do I need to do anything codewise? I figured that the app would look at the certificates located on the phone, and use this. The way Chrome seems to do. But some guides tell me that I manually have make a keystore and supply this to the SSLFactory (Link to guide). But on other pages it seems that this should work out of the box...
Can anyone point me in the right direction?

Android: CertPathValidatorException - TrustAnchor found but certificate validation failed

I am trying to authenticate my android application over a https connection to the server.
I a getting the following exception while trying to authenticate. While looked up for solution, there were lots of suggestions about binding certificate with apk, ignoring the certificate validation etc.
Detailed StackTrace
The problem is, in few phones and emulators this authentication over https works perfectly fine. And in my phone as well as in my emulator it doesn't go through. So looks like its more of a device issue than code one.
Has anyone else have faced this kind of issue and sorted out?

The error meaning is: the SSL certificate chain (from the server certificate to a trust anchor in the Root CA store) has been rebuild by the application but the validation of this chain failed for any reason.
In the stacktrace the underlying error is java.security.NoSuchProviderException: AndroidOpenSSL. It means that the application tries to instantiate a signature validation object with a cryptographic provider which is not present in the android system. This error makes me thinking that it may be an android version issue.
Can you tell us the target API level used to build your application? And what are the versions of the terminals on which the application works and does not work?