Since Apple controls the entire hardware/software stack, is it possible to obtain the following (through some type of trusted computing):
the hardware certifies that the software is genuine, non-jail broken iOS
iOS certifies to my server that the app run is an unmodified app
What this achieve is as follows:
when my server sends out data, it is guaranteed that the data can only be used in the way I intend it to be used (since it's running my app unmodified, on an non-jail broken iOS).
This prevents things like a modified app which steals data being transmitted from the server to the client. I realize one could theoretically eavesdrop, but this can be eliminated via encryption.
Thanks!
Briefly, no.
You're talking about Trusted Computing concepts on a platform that does not support TC. IOS does not include anything near Trusted Computing - Remote Attestation. It has no TPM.
The chain of trust established by Apple chip merely tries to stop execution if the signature of the next element in the boot chain is invalid. If one thing fails (jailbroken), their's no real -effective- way of detecting it. It is very similar to Secure Boot introduce by Microsoft but it's very different then Trusted Computing which attest which version of the system it is currently running.
With Trusted Computing, the TPM store the measurements (PCRs) of the system boot (SRTM). At boot, the first thing executed (CRTM - the only thing we really need to trust implicitly) will start the chain by measuring the BIOS, send the measure to the TPM (in a PCR) and pass execution to it (the BIOS). Then the BIOS does the same thing for the next element in the boot chain.
The measurements stored in the PCRs can then be used to encrypt or decrypt information (SEAL/UNSEAL operations) depending on the environment loaded in memory.
The TPM does not take action on the measurements (good or bad). The idea is not to restrain what can be loaded but to being able to know what environment is loaded on the platform. If something has been modified, the TPM will not contain the proper PCRs values and the UNSEAL operation (decrypt using PCRs as the key) will not work.
In the case of Remote Attestation, we're talking about the QUOTE operation. It's basically the same thing then SEAL but uses other keys to make sure the evaluating party can validate the attestation is really coming from a real/compliant TPM.
Sure, a system could use the SEAL operation to protect a secret used to decrypt the operating system and thus produce -in some way- the same effect as secure boot.
For more info, see my other posts.
Related
I am writing a script having user personal information like "User Id", "Password", "Server detail", Bla bla bla. And I want to secure these all personal data.
And you know, Script inside Nodemcu is not secure at all. Anybody can download the script and make a cop of my project.
So, I want to encrypt the script which is uploaded in the Nodemcu so that some other can not decrypt or read my script.
Is it possible in NodeMCU?
I am using NodeMCU V3(Written at the back side of nodemcu)
Initial Details :
NodeMCU custom build by frightanic.com
branch: 1.5.4.1-final
commit: b9436bdfa452c098d5cb42a352ca124c80b91b25
SSL: false
modules: file,gpio,mqtt,net,node,rtctime,tmr,uart,wifi
build created on 2019-09-21 17:56
powered by Lua 5.1.4 on SDK 1.5.4.1(39cb9a32)
lua: cannot open init.lua
It is possible to achieve high security level but not 100%. NodeMCU stores data in external flash which is not protected from reading, even encrypted.
You need at least a firmware with standard crypto and TLS modules for basic encryption. Without TLS encryption (as module for net communication) you are vulnerable event without touching your device.
Better, is to use modified firmware with custom encryption/decryption functionality using internal unique chip id's as part of key, making it harder to break.
Some interesting ideas: https://bbs.espressif.com/viewtopic.php?t=936
To protect your scripts, compile in binary form without storing original scripts: https://nodemcu.readthedocs.io/en/master/compiling/
Edit:
In module crypto you can add a modified version of crypto_encdec() as encryptintern/decryptintern with predefined/calculated key and iv.
To get device specific id for key calculation you can use MAC address with wifi_get_macaddr() and flash id with spi_flash_get_id() as suggested: https://bbs.espressif.com/viewtopic.php?t=1303
To encrypt/decrypt compiled scripts you can modify luaL_loadfile (require uses it too) to decrypt files, and luac.c for encryption on your host.
Note that nothing will help against an even halfway determined person. It's trivial to dump the contents of flash, find keys, and decrypt everything. Without hardware support (there are cheap crypto chips out there), it is impossible to secure these devices.
Depending on your situation, there are alternatives; for example, for my home usage I'm planning to set up a separate WiFi network that's low security (no access to internet, just IoT devices) once I start deploying ESP8266 based devices. Yes, people can easily get the credentials but you'll be connected to a mostly useless network.
Security is very situational. What kind of attackers are you protecting against? How valuable is what you are protecting? It's hard to give advice without knowing more about that.
Okay, this question applies to most scenarios where a vendor distributes an SDK binary to 3rd party developers to use. But for easier discussion, let's assume I am developing an iOS SDK in Objective-C, and planning to hand it to any developers who have registered on our portal.
This SDK will access our services located on our server. And since the resources on our server are limited (well, on any server actually), we have built in some simple throttling mechanism in the SDK to prevent bad use of API's, like putting a remote procedure calls in a loop which executes 10K times a second, whether purposefully or not. Anytime such a thing happens, we throw.
As long as the developers use the binary as is, things are fine. But what if someone tries to do some funny things, like breaking our throttling mechanism by changing the binary, then linking to their app? In such a case, our client throttling mechanism no longer works, and a few instances of their app running could bring our server down.
Our thought is that we can build some checksum validation mechanism in the SDK binary, then calculate the binary's checksum during runtime initialisation, and compare that to the one in the binary. If our binary is tampered with, we cancel the initialisation, and prevent the host app from using our resources.
We already have server-side throttling mechanism on the server. But we also throttle on the client, since many unthrottled requests to the server still consume resources unnecessarily on the server, even we have throttling ready on the sever.
Is that a viable thought? Anyone have experience on this matter?
Thanks!
I've noticed several tutorials for most of the major players in social networks have examples where a API key tied to your account is embedded (usually in plan text) in the source code. For example, Google Maps APIs Premium Plan. This key is used to bill your company.
I found a similar question in Is it safe to put private API keys in your .m files when exporting to the appstore?1 - Of note, anyone with a jailbroken phone can see the unencrypted executable.
Is this practice actually safe, and if so, why?
Embedding API keys in an app is not secure and generally not a good practice but does require a substantial work factor to obtain them, it is not trivial. There is no tool to decrypt the executable other than the OS for execution.
RE: "anyone with a jailbroken phone can see the unencrypted executable." is not really true. Just jailbreaking will not decrypt the app binary, it is only decrypted as the binary is loaded in RAM to execute and the key will not be available, it is decrypted in hardware in the DMA path. One needs to add debugging tools and catch the binary after it is loaded into memory for execution.
You need to determine who the attacker is, how much skill and time the attacker will spend and the cost to you.
There is no 100% secure solution, only increasing the work factor.
An alternative is to obtain the API keys on first run at login to a server and then move them to the Keychain. But this is also just an increase in work factor because as above the executable can be examined at run time when it is sent to the service.
As long as the key has to be in the app memory during any part of execution it is vulnerable.
Putting the API keys in the source may meet the security needs.
What are the best practices to add sensitive data to the iOS application?
For sensitive data I mean a key or token to communicate with some external server.
Can we compile a certificate in the app, and iOS can remove it on installation?
I feel like we can not really 100% guarantee security of it, but what is the best practice layer we can add.
There is no mechanism that will ensure to a server that only your application is allowed to speak to it. So if that is your goal, then it is unsolvable. This has been talked to death on SO. Just a few:
Secure Communication Between iPhone and Server?
Store an encryption key in Keychain while application installation process
Secure https encryption for iPhone app to webpage
(And the many other links within those postings.)
And elsewhere:
Obfuscating Cocoa
You cannot authenticate devices or software. You can only authenticate users. That means a login. Without a login that is partially stored in the user's brain (or at least in something separate from their iPhone), it's just obfuscation.
Now, that doesn't mean that obfuscation is useless. It isn't. You can get some mileage out of a simple authentication token (like a client key), but don't expect it to survive an attack. That doesn't mean you shouldn't do it; it just means you shouldn't spend a lot of time/money on it since it will fail pretty fast.
In no cases should you implement something that ticks off paying customers. Read the several threads linked above (and the several threads linked from those threads). If after that, you still absolutely need a solution, then you'll need to hire someone to keep track of the cracks and fix them every time a new one comes out. It will never stop.
Background:
I got some data encrypted with AES (ie symmetric crypto) in a database. A server side application, running on a (assumed) secure and isolated Linux box, uses this data. It reads the encrypted data from the DB, and writes back encrypted data, only dealing with the unencrypted data in memory.
So, in order to do this, the app is required to have the key stored in memory.
The question is, is there any good best practices for this? Securing the key in memory.
A few ideas:
Keeping it in unswappable memory (for linux: setting SHM_LOCK with shmctl(2) ?)
Splitting the key over multiple memory locations.
Encrypting the key. With what, and how to keep the...key key.. secure?
Loading the key from file each time its required (slow and if the evildoer can read our memory, he can probably read our files too)
Some scenarios on why the key might leak: evildoer getting hold of mem dump/core dump; bad bounds checking in code leading to information leakage;
The first one seems like a good and pretty simple thing to do, but how about the rest? Other ideas? Any standard specifications/best practices?
Thanks for any input!
All depends on the level of your paranoia and the sensitivity of the key/data. In the extreme cases, as soon as you have an unencrypted key in memory, one can retrieve it using coldboot techniques. There is an interesting development at frozencache to try to defeat that. I merely casually read it, did not try it in practice, but it seems like an interesting approach to try.
With the tinfoil hat off, though - (1), (2), (3) do seem reasonable. (4) won't cut it precisely for the reason you mentioned. (Not only it is slow, but assuming you read into the stack, with different stack depths the key might become visible more than once).
Assuming the decrypted data is worth it, and it would be in the swappable memory, you definitely should encrypt the swap itself as well. Also, the root, /tmp partitions should also be encrypted. This is a fairly standard setup which is readily available in most guides for the OSes.
And then, of course, you want to ensure the high level of physical security for the machine itself and minimize the functions that it performs - the less code runs, the less the exposure is. You also might want to see how you can absolutely minimize the possibilities for the remote access to this machine as well - i.e. use the RSA-keys based ssh, which would be blocked by another ACL controlled from another host. portknocking can be used as one of the additional vectors of authentications before being able to log in to that second host. To ensure that if the host is compromised, it is more difficult to get the data out, ensure this host does not have the direct routable connection to the internet.
In general, the more painful you make it to get to the sensitive data, the less chance someone is going to going to get there, however there this is also going to make the life painful for the regular users - so there needs to be a balance.
In case the application is serious and the amount of things at stake is high, it is best to build the more explicit overall threat model and see what are the possible attack vectors that you can foresee, and verify that your setup effectively handles them. (and don't forget to include the human factor :-)
Update: and indeed, you might use the specialized hardware to deal with the encryption/decryption. Then you don't have to deal with the storage of the keys - See Hamish' answer.
If you are serious about security then you might consider a separate cryptographic subsystem. Preferably one that is FIPS 140-2/3 certified (list of certified modules).
Then the key is held in tamper proof memory (non-extractable) and all cryptographic operations are performed inside the crypto boundary.
Expensive but for some applications necessary.
Also don't forget the threat of core dumps and your memory being swapped out!
On both POSIX (like Linux) and Windows systems, there are techniques to prevent that from happening if you're dealing with C language - see this section from CERT Secure Coding Standards:
MEM06-C. Ensure that sensitive data is not written out to disk
The big problem is the program has to read the key from somewhere. Unless you accept direct keyboard input each time the server reboots, it pretty much has to exist on disk somewhere.
In general you have to assume the evildoer doesn't have access to the root level operating system or hardware as when that's the case they'll eventually manage to get the key even if it's only in RAM.
So you assume the server's OS is secure. But let's say somebody can come and steal the hard drive so starting the server would give them the key. Then let the server ask another server for half of the key, the remote server validates the request (using ip, private/public key pairs) and supplies half the key. Then your server has a complete key, and the remote server never has more than half. That seems to me an improved level of protection.
I'd be looking at what
openssh,
openssl,
GnuPG (see related sub-projects via the project-root dropdown), and
GnuTLS
do when handling keys. They're sufficiently paranoid about such security matters...
Use of "super super user" hardware memory is ideal. All Intel Macs have this SecureEnclave memory area and it also includes an AES decryption in hardware such that the application and operating system never have access to the raw private key. When the machine boots, a password is typed in (optional), and the SecureEnclave decrypts its cold flash memory encrypted version of the key into its RAM area, which is not accessible by the main operating system.
Nice side effect is the hardware accelerated encryption: I benchmarked 600 MB/sec writes to my PCIe storage on a freshly formatted encrypted disk.
In the cloud, Amazon have this AWS Key Management Service (KMS) managed service that makes it easy for you to create and control the encryption keys used to encrypt your data, and uses FIPS 140-2 validated hardware security modules to protect the security of your keys: https://aws.amazon.com/kms/