有谁能帮助我理解为什么我会得到两个不同的密钥哈希值？

Question

I found two different methods to get the key hash for an android application:

1. Using a Java method:

 public void generateHashkey() {
    try {
        PackageInfo info = getPackageManager().getPackageInfo(
                "package_name",//TODO: change to your package name.
                PackageManager.GET_SIGNATURES);
        for (Signature signature : info.signatures) {
            MessageDigest md = MessageDigest.getInstance("SHA");
            md.update(signature.toByteArray());
            Log.d("Signature", Base64.encodeToString(md.digest(),
                    Base64.NO_WRAP));
        }
    } catch (PackageManager.NameNotFoundException e) {
        Log.d("Signature", e.getMessage(), e);
    } catch (NoSuchAlgorithmException e) {
        Log.d("Signature", e.getMessage(), e);
    }
}

2. Fetch form Keystore:

keytool -exportcert -alias alias_name -keystore keystore_path | openssl sha1 -binary | openssl base64

Now my question is: I'm getting two different key hash from these two methods, why so?

If these methods return two different hashes, which one should I use?

As I register my app on FB with hash generated by using the 2nd method and when I try FB login in my app(live/production) it is asking for hash generated by the 1st method.

Answer 1

Are you possibly using different hashing algorithms? Your code shows you are using one version of the SHA hash your command line is specifically asking for SHA1?

This discussion of hashing options may help you.

What specific hash algorithm does MessageDigest.getInstance("SHA") return?