Developer Libraries » Trusted Intents

import android.widget.Toast;

import java.security.NoSuchAlgorithmException;

        String sha1;

        try {

            sha1 = Utils.getCertificateFingerprint(appEntry.getApkFile(), "sha1");

        } catch (NoSuchAlgorithmException e) {

            e.printStackTrace();

            Toast.makeText(getActivity(), "Cannot make fingerprint of signing certificate",

                    Toast.LENGTH_LONG).show();

            return;

        }

        intent.setData(Uri.parse("https://androidobservatory.org/?searchby=certhash&q=" + sha1));

import java.io.InputStream;

import java.security.cert.Certificate;

import java.security.cert.CertificateEncodingException;

import java.util.jar.JarEntry;

import java.util.jar.JarFile;

    public static String getCertificateFingerprint(File apkFile, String hashAlgorithm)

            throws NoSuchAlgorithmException {

        byte[] rawCertBytes;

        try {

            JarFile apkJar = new JarFile(apkFile);

            JarEntry aSignedEntry = (JarEntry) apkJar.getEntry("AndroidManifest.xml");

            if (aSignedEntry == null) {

                apkJar.close();

                return null;

            }

            InputStream tmpIn = apkJar.getInputStream(aSignedEntry);

            byte[] buff = new byte[2048];

            while (tmpIn.read(buff, 0, buff.length) != -1) {

                /*

                 * NOP - apparently have to READ from the JarEntry before you

                 * can call getCerficates() and have it return != null. Yay

                 * Java.

                 */

            }

            tmpIn.close();

            if (aSignedEntry.getCertificates() == null

                    || aSignedEntry.getCertificates().length == 0) {

                apkJar.close();

                return null;

            }

            Certificate signer = aSignedEntry.getCertificates()[0];

            apkJar.close();

            rawCertBytes = signer.getEncoded();

            MessageDigest md = MessageDigest.getInstance(hashAlgorithm);

            String hash = toHexString(md.digest(rawCertBytes));

            md.reset();

            Log.i("SigningCertificate", "raw hash: " + hash);

            return hash;

        } catch (CertificateEncodingException e) {

        } catch (IOException e) {

        }

        return "BAD_CERTIFICATE";

    }