Does every Android phone support SHA-256

Question

So reading this post: How can I calculate the SHA-256 hash of a string in Android?

and the docs: http://developer.android.com/reference/java/security/MessageDigest.html

I'm curious; which phones will support SHA-256? In the docs, the line about the 'NoSuchAlgorithmException' makes me think that some phones don't support all algorithms. Before I go implementing this for an app and expecting it to work the same on all phones I want to know if anyone knows anything about this...?

I find it strange that the MessageDigest class doesn't have some constants to pick the algorithm you want to use.

Answer 1

SHA-256withRSA is NOT supported in older android versions (verified the same in Android 4.0.3, 4.1.1). I have experienced this problem while using JSCEP. The digest algorithm returned by SCEP server is SHA-256. But SHA-256withRSA is not present in any default SecurityProviders in those android versions. Found a relevant link: Which versions of Android support which package signing algorithms?

This link shows that SHA-256withRSA was added later: https://android-review.googlesource.com/44360

Answer 2

All Android devices support SHA-256. The NoSuchAlgorithmException indicates that a requested algorithm could not be found and is necessary because the method takes a String argument for the algorithm name. If you passed in "foo-256", the method's only recourse is to throw a NoSuchAlgorithmException because, for reasons beyond my understanding, there's no algorithm called "foo-256". Assuming you're passing in a name you're sure is an algorithm that Android can use, you'll never see that exception.

Answer 3

Add NoSuchAlgorithmException as below:

public static String SHA256 (String text) throws NoSuchAlgorithmException {

    MessageDigest md = MessageDigest.getInstance("SHA-256");

    md.update(text.getBytes());
    byte[] digest = md.digest();

    return Base64.encodeToString(digest, Base64.DEFAULT);
}