I have a scenario where I need to implement a digital signature scenario in iPhone and web. Simply I will first generate the RSA signature in iPhone end and share the public key with the server. Also server public key will be there using the x509 certificate generated from server. I can copy that over to the iPhone folder structure. The idea of this is to use this as digital signature where server will send a message by encrypting by the servers private key and again by iPhone public key. From iPhone end it can decrypt using iPphone private key and verity that again by decrypting using server public key.
I went through the sample code provided by Apple but they are not easy to understand. And it didn't cover my requirements as well. Here are my questions.
1) Can my objective achieved?
2) Will iPhone and my server back end (Java) work together cos many forums said that it had issues cos it has DER encoding.
3) Many samples focus on installing the own certificate in iPhone key chain. Can I install the server x509 as well?
4) Any link or material which will focus on my requirement or any guidance is appreciated.
Related
To access a public server, I was asked to generate a CSR. I generated the CSR using the Windows MMC snap-in, which was then validated by the authorities, and a CER file was issued to me. I have successfully imported that CER file as well.
However, I am unable to locate the private key corresponding to this CSR. Need serious help here. No option was specified to save the pvt key, even though the checkbox to make it exportable was selected.
The MMC console mentions that a private key exists for this certificate - but does not specify where.
Have managed to export the certificate to a PFX file (asked for a passcode - provided one) - but for all my attempts, extracting the private key from PFX without using any commercial tool is proving to be challenging (using any commercial or online tool is not permitted, unfortunately). (Have trawled through quite a few SO posts - too numerous to be listed).
Will be happy to write a program (in C or Assembly) if that helps extract the private key.
Thanks for your attention.
I'm debating and need to know the implications of not using the SCEP protocol for the mdm enrolment, more precisely the Identity certificate (the certificate credential used for authentication). I'm talking about the certificate in the Identity section on IPCU, as shown in the image below, with the red arrow.
I wont be pushing down profiles with sensitive informations (like vpn, email, etc configurations and/or passwords).
My use case will be 99%:
Block/unblock apps by rating
Lock/unlock device
Block/unlock web domains
From reading around StackOverflow (here and here) the following scenarios can happen.
If someone get access to the certificate he will be able to impersonate an enrolled device, but he will only be able to receive commands/profiles and not initiate commands/profiles. Am I right?
A man in the middle attack can get access to the certificate
The advantage of using the PKCS12 embedded within the profile is that it is faster to implement and no external dependencies (SCEP server) but I'm not so sure about the disadvantages. So my questions and doubts is:
What can a malicious person do with the private key from the Identity certificate?
Can it be a security breach going with the PKCS12 embedded approach?
This is mostly a question of SCEP vs PKCS12 embedded within the profile, pros and cons.
Here my thought on that:
1) If you are building a prototype or a small not critical service then go with PKCS12.
2) If you are building a serious product (production and touching devices of people with sensitive info) then go with SCEP (you can get a free SCEP servers. It's not that complex).
Frankly, If I was on the dark side (trying to hack it) I don't think that I would attack PKCS12 vs SCEP (it's not the weakest link)
However, let say, I say I decided to try to hack it
I would try to do man in the middle. I will try to capture communicarion, save PKCS12 and password for it
I will use it to authenticate to MDM server.
You are right, I can't trigger any commands, but I can start probing your code to find where you skipped some security checks. Maybe you don't check that a certificate matches a device UUID and so on.
Hopefully, I will find enough security holes to do something (let say trigger actions for other users). Maybe I will send them Wipe command or may be I will try to install a root CA + HTTP proxy configuration to see all their traffic.
Anyhow. I don't think that it's that weakest link and it requires a lot of additional step to get to some interesting stuff. However, if you get there, you can do A LOT.
As a result for a serious product, it will make sense to invest several additional weeks in SCEP.
I have few questions regarding Identity certificate in Profile Payload.
Forgive the ignorance, if some questions are basic.
1.) I found that, we can either use SCEP standard or PKCS12 certificate directly for device identification. SCEP is recommended, since private key will be known only to the device. So in case If I am going to implement SCEP server, do I need to maintain the list of Public key of Identity certificates mapped to the device, so that I can use it later for encrypting?
2.) What is the best possible way to implement SCEP server.? Is there any reliable robust methods available to adopt it instead of writing everything on our own?
3.) What if the identity certificate is expired?
As a basic version while playing around, I tried to add my own p12 certificate to the Payload without using SCEP.
I tried to add the base64 encoded p12 certificate in the identity payloadcontent key,as mentioned in some link reference. I got an error
The identity certificate for “Test MDM Profile” could not be found
while installing profile.
identity_payload['PayloadType'] = 'com.apple.security.pkcs12'
identity_payload['PayloadUUID'] = "RANDOM-UUID-STRING"
identity_payload['PayloadVersion'] = 1
identity_payload['PayloadContent'] = Base64.encode64(File.read "identity.p12")
identity_payload['Password'] = 'p12Secret'
When I checked 'Configuration Profile key reference', it was mentioned that I should send Binary representation of Payload in Data.
So I tried,
identity_payload['PayloadContent'] = ConvertToBinary(File.read "identity.p12")
I got,
The password for the certificate “IdentityCertificate” is incorrect
I am supplying valid password for exporting the p12 certificate.
What am I doing wrong?
Answering your question:
1) Do I need to maintain the list of Public key of Identity certificates mapped to the device, so that I can use it later for encrypting?
Yes. You need some kind of mapping. You can do couple of ways:
Just store it in DB a mapping between certificate common name and device UDID.
Make CN contain UDID (I like this method, because it simplifies initial checks)
And as you pointed out you will need public key to encrypt payloads for this device.
2) What is the best possible way to implement SCEP server.? Is there any reliable robust methods available to adopt it instead of writing everything on our own?
There are open source implementation of SCEP. As example jSCEP have it (I used it) and EJBCA have it (I used it too). I saw other implementation (in Ruby and so on). So, you can find an choose something which works with your stack.
3) You need to renew identity certificate before it expeires (the same way as for any other certificates).
4) If your profile doesn't work, I would recommend you to create the same profile in iPhone Configuration Utility and compare with yours. Most of the time, you missed just one tag or something like that (it will take a lot to figure it out without comparing it with working one).
I'm trying to verify a GameCenter player on a remote server using Apple's documented method:
GKLocalPlayer generateIdentityVerificationSignatureWithCompletionHandler:
Calling this method on iOS returns, among other things, a link to this file (this file location is fairly static, and you can download it to see its contents):
https://sandbox.gc.apple.com/public-key/gc-sb.cer
This file holds the public key that must be downloaded on the server to begin the verification process for the local GameCenter player.
I am using Google App Engine for my project, which limits me to using the PyCrypto library. I am trying to import this file using these calls (I use the filename directly here for clarity):
from Crypto.PublicKey import RSA
apple_cert = urllib2.urlopen("https://sandbox.gc.apple.com/public-key/gc-sb.cer").read()
rsakey = RSA.importKey(apple_cert)
Unfortunately, this is failing with the following message:
raise ValueError("RSA key format is not supported")
From what I understand, PyCrypto is expecting a DER formatted certificate, which is what I think Apple is supplying. Does anyone know what I'm doing wrong, or can point me in the right direction? Thanks.
Also, I have setup my GAE project to use the latest version of PyCrypto, which I think is 2.6.
The process of getting GameCenter authentication working with Google App Engine is proving to be very troublesome.
As it turns out, the reason is because the file downloaded from Apple is actually an X.509 certificate. The public key has to be extracted from this certificate before it can be used. This answer is demonstrated in a similar post:
How do I use a X509 certificate with PyCrypto?
For the full solution on validating a GameCenter user using Google App Engine, see my answer in this post:
How to authenticate the GKLocalPlayer on my 'third party server'?
I am working on an Apple MDM server, and actually it is working fine. I have a signature problem, that makes the client complain about the certificate, so now I am interested in how others sign their configuration profiles.
I use java, but any kind of help is welcome, since this is not a particular question on how to implement the code in java, but more on how to correctly sign the configuration profile.
This is how we do it currently:
byte[] data = ...
X509Certificate cert = ...
KeyPair keyPair = ...
CMSSignedDataGenerator gen = new CMSSignedDataGenerator();
gen.addSigner(keyPair.getPrivate(), cert, CMSSignedGenerator.DIGEST_SHA1, new AttributeTable(new Hashtable<DERObjectIdentifier, Attribute>()), null);
CMSSignedData signedData = gen.generate(new CMSProcessableByteArray(data), true, "BC");
response.setContentType("application/x-apple-aspen-config");
response.getOutputStream().write(signedData.getEncoded());
We are using a self signed certificate created with the algorithm SHA1withRSA and the key is with RSA and the size is 2048.
Does anyone see a problem with this way of doing it, or are you just doing it differently which maes it work?
And please feel free to post code in other languages than java - it might still help.
I did two things to fix this.
First I changed the certificate to x509 v3 - it was v1. Then I added KeyUsage and BasicConstraints to make iOS accept it as trusted.
The second I did was to add the certificate itself as a CertStore.
These two steps makes the certificate similar to the certificate iPhone Configuration Utility uses.