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09 - Android Security (2)
Lecture
Practical
Task 1 - Fetch web page through HTTP (3p)
Create an application that downloads a web page through HTTP. The activity includes an EditText, a Button and a TextView. The user introduces an URL and clicks on the button to obtain the contents of the web page.
Steps:
When the Button is clicked, check network connectivity through the ConnectivityManager
Then, perform network operations in an AsyncTask
Use HttpURLConnection for performing HTTP GET requests
Get associated InputStream for receiving the reply
The reply is displayed in the TextView
Resources:
Task 2 - Fetch web page through HTTPS (1p)
Modify the previous application in order to obtain web pages through HTTPS. Use HttpsURLConnection.
Resources:
Task 3 - Display system trust store (3p)
The Android system includes a system (default) trust store, which includes a list of trusted Certificate Authorities (CAs).
Modify the previous application in order to display the system trust store using TrustManager.
Steps:
Obtain an instance of TrustManagerFactory and initialise it
Obtain an instance of the first TrustManager (X509TrustManager)
Display information about each trust anchor (X509Certificate)
Resources:
Task 4 - Use a custom trust store (3p)
The previous application will not be able to fetch web pages on a server with a certificate that is issued by an unknown CA. For example: https://certs.cac.washington.edu/CAtest/, which uses certificate issued by UW Services Certificate Authority (which is not trusted by Android by default). Extend the application in order to be able to access this URL, by loading and using a custom trust store.
Steps:
Save certificate file (uwca.crt) from server and put it in res/raw/
Load trusted CAs from file
Create a KeyStore object and insert the trusted CAs
Obtain an instance of TrustManagerFactory and initialise it
Obtain an instance of SSLContext and initialise it
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Obtain an HttpsURLConnection
Configure the HttpsURLConnection to use the SocketFactory from the SSLContext
Read from an InputStream
Resources: