Personally, I would use SHA256 instead of SHA1. That's what I did in SignatureUtils
in my CWAC-Security library:
/***
Copyright (c) 2014 CommonsWare, LLC
Licensed under the Apache License, Version 2.0 (the "License"); you may
not use this file except in compliance with the License. You may obtain
a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package com.commonsware.cwac.security;
import android.content.Context;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.pm.Signature;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
public class SignatureUtils {
public static String getOwnSignatureHash(Context ctxt)
throws NameNotFoundException,
NoSuchAlgorithmException {
return(getSignatureHash(ctxt, ctxt.getPackageName()));
}
public static String getSignatureHash(Context ctxt, String packageName)
throws NameNotFoundException,
NoSuchAlgorithmException {
MessageDigest md=MessageDigest.getInstance("SHA-256");
Signature sig=
ctxt.getPackageManager()
.getPackageInfo(packageName, PackageManager.GET_SIGNATURES).signatures[0];
return(toHexStringWithColons(md.digest(sig.toByteArray())));
}
// based on https://stackoverflow.com/a/2197650/115145
public static String toHexStringWithColons(byte[] bytes) {
char[] hexArray=
{ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B',
'C', 'D', 'E', 'F' };
char[] hexChars=new char[(bytes.length * 3) - 1];
int v;
for (int j=0; j < bytes.length; j++) {
v=bytes[j] & 0xFF;
hexChars[j * 3]=hexArray[v / 16];
hexChars[j * 3 + 1]=hexArray[v % 16];
if (j < bytes.length - 1) {
hexChars[j * 3 + 2]=':';
}
}
return new String(hexChars);
}
}
If you really want SHA1, you should be able to change the MessageDigest.getInstance()
call to suit. And, if colon-delimited pairs of hex digits isn't your desired output format (I chose it to match keytool
), you can convert the byte[]
into a printable output in some other fashion if you wish.