I've now found the answer to this question, but I'll leave it for the sake of anyone looking in the future.

I opened up a discussion on android-security-discuss where it was answered. Link: http://groups.google.com/group/android-security-discuss/browse_thread/thread/e01f63c2c024a767

Short answer:

    private boolean checkAuthorised(){
        PackageManager pm = getPackageManager();
        try {
            for (Signature sig :
                pm.getPackageInfo(pm.getNameForUid(getCallingUid()),
                        PackageManager.GET_SIGNATURES).signatures){
                LogUtils.logD("Signature: " + sig.toCharsString());
                if (Security.trustedSignatures.get(sig.toCharsString()) != null) {
                    return true;
                }
            }
        } catch (NameNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        LogUtils.logD("Couldn't find signature in list of trusted keys! Possibilities:");
        for(String sigString : Security.trustedSignatures.keySet()){
            LogUtils.logD(sigString);
        }

        /* Crash the calling application if it doesn't catch */
        throw new SecurityException();

    }


Where Security.trustedSignatures is a Map of the form:

Map&lt;String,String&gt;().put("public key","some description eg. name");


Put this method inside any code that is being called by the external process (ie. within your interface). Note that this will not have the desired effect inside the onBind() method of your RemoteService.

Implement signature-level security on Android services with more than one allowed signature
Focus and blur have a reason in a picture when they come together. Blur alone is just a loss of an important element in the photography art, unless it has a reason, like obscuring nudity or creating an additional value... but what is the value of an entirely blurred picture?
