Use Digital Signatures to protect your products
emSecure is a software solution to securely authenticate digital assets. It can be used to secure products at no per unit cost against hacking and cloning.
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|Whitepaper: Fighting product clones through digital signatures|
What is emSecure?
emSecure is a SEGGER software package that allows creation and verification of digital signatures.
One important feature is that emSecure can make it impossible to create a clone of an embedded device by simply copying hardware and firmware.
And it can do much more, such as securing firmware updates distributed to embedded devices and authenticating licenses, serial numbers, and sensitive data.
emSecure offers 100% protection against hacking. It is not just nice to have, but in fact a must-have, not only for critical devices such as election machines, financial applications, or sensors.
Compromised devices are dangerous in several ways, not just from a commercial point of view. They hamper manufacturers' reputation and might entail severe legal disputes. Not addressing the issue of hacking and cloning is irresponsible.
Based on asymmetric encryption algorithms with two keys, emSecure signatures cannot be forged by reverse engineering of the firmware. A secure, private key is used to generate the digital signature, whereas a second, public key is used to authenticate data by its signature. There is neither a way to get the private key from the public key, nor is it possible to generate a valid signature without the private key.
The emSecure source code has been created from scratch for embedded systems, to achieve highest portability with a small memory footprint and high performance. However, usage is not restricted to embedded systems.
With its easy usage, it takes less than one day to add and integrate emSecure into an existing product.
emSecure is a very complete package, including ready-to-run tools and functionality for generation of keys and signatures.
Why should I use emSecure?
If you want to check the integrity of your data, for instance the firmware running on your product, you would normally include a checksum or hash value into it, generated by a CRC or SHA function. Hashes are excellent at ensuring a critical data transmission, such as a firmware download, has worked flawlessly and to verify that an image, stored in memory, has not changed. However they do not add much security, as an attacker can easily compute the hash value of modified data or images.
Digital signatures can do more. In addition to the integrity check, which is provided by hash functions, a digital signature assures the authenticity of the provider of the signed data, as only he can create a valid signature.
emSecure comes in different versions with different digital signature algorithms to fit any requirements of size or speed.
emSecure can be used for two security approaches:
1. Anti-hacking: Prevent tampering or exchange of data, for example the firmware running on a product, with non-authorized data.
2. Anti-cloning: Prevent a firmware to be run on a cloned hardware device.
Anti-Hacking — Authentication of firmware
To make sure only authorized firmware images are run on a product the firmware image will be signed with emSecure.
To do this an emSecure key pair is generated one time.
The private key will be included in the production process of the firmware. Once a firmware is created and ready to be shipped or included into a product it will be signed with this private key. The signature will be transferred and stored in the product alongside the firmware.
Firmware signing in production:
The public key will be included in the bootloader of the product, which manages firmware updates and starts the firmware.
On a firmware update and when starting the product, the bootloader will verify the firmware by its signature. If they match, the firmware is started, otherwise the application will stay in the bootloader or even erase the firmware.
Anti-Hacking Bootloader Verification:
Anti-Cloning — Authentication of hardware
To make sure a product cannot be re-produced by non-authorized manufacturers, by simply copying the hardware, emSecure will be used to sign each genuine product unit.
First an emSecure key pair is generated one time. This is likely done at the production site.
Hardware signing in production:
The private key will be included in the production process of the product. At the end of the production process, after the unit is assembled and tested, some hardware-specific, fixed, and unique data, like the unique id of the microcontroller is read from the unit. This data is signed by emSecure with the private key and the signature is written back to the unit into an OTP area or a specified location on memory.
The public key will be included in the firmware which will run on the product. When the firmware is running it will read the unique data from the unit and verify it with the signature. When the signature does not match, for example, when it was simply copied to a counterfeit unit with other unique data, the firmware will refuse to run.
Anti-Cloning Firmware Verification:
Advantages of emSecure
emSecure has been created from scratch to achieve highest portability and performance with a very small memory footprint. It enables you to profit from the security of digital signatures in embedded applications, even on small single-chip microcontrollers without the need of additional hardware such as external security devices or external memory.
SEGGER offers different versions of emSecure which use different signature algorithms to fit any requirement of size or speed. The structure of each version is similar to make all of them easily usable and expandable.
emSecure is a complete package. It includes ready-to-run tools to generate keys and signatures, to sign and verify data and to convert the keys and signatures into compilable formats.
emSecure includes all required source code to integrate signature generation directly into your production process and data verification into your application or firmware.
emSecure has a simple yet powerful API. It can be easily integrated into an existing application within one day.
emSecure incorporates proven security algorithms as proposed by NIST. The algorithms are proven to be cryptographically strong and can provide a maximum of security to your applications.
emSecure is licensed in the same way as other SEGGER middleware products and not covered by an open-source or required-attribution license. It can be integrated in any commercial or proprietary product without the obligation to disclose the combined source. It can be used royalty-free in your product.
emSecure version comparison
emSecure is available in different versions which use different signature algorithms.
Each signature algorithm has different characteristics. The emSecure products can provide security for any requirement of size or speed.
The table below lists some benefits of the different emSecure versions. For a complete overview and performance values, please refer to the subpage of the product.
Sign & Verify drag-and-drop application
The Sign & Verify Application enables easy drag-and-drop creation of emSecure digital signatures and verification of signed files. It may be used freely for personal use to, for example make sure files stored on a server are not changed or to allow communication partners to send/receive files knowing nothing has been changed during transmission. More information about emSecure Sign & Verify.
The emSecure Package
emSecure is a complete package that comes with everything needed:
A utility to generate the private and public keys, code to calculate secure hashes, encrypt and decrypt messages and create and verify digital signatures.
All parts of the package conform to the relevant FIPS specifications issued by NIST and have been tested against standard test vectors to prove the implementation.
emSecure is provided in source code with example applications precompiled for your convenience.
The source code gives complete control of the code that goes into a product and its production facility.
Additional measures to keep the system secure
When it comes to the degree of security emSecure offers, there is an easy answer: It is unbreakable because no one can generate a valid signature without knowledge of the private key.
Putting enough effort into getting the bootloader or firmware image, disassembling and analyzing it and modifying the application to bypass the security measures, hackers might be able to clone a product or use alternative firmware images. However this will only work until a firmware update is done.
There are additional ways to increase overall system security:
- The private key has to be kept private.
- Private keys should best be generated on a dedicated machine that has no connection to a network and controlled access.
- RSA private keys can be generated from a pass-phrase, which means the pass-phrase should not be too easy to guess. The pass-phrase length is not limited. The company name is not a good choice. The pass-phrase has to be kept private, too.
- The private key might also be encrypted and is only decrypted while it is used in production.
- The bootloader should should be stored in a memory which can be protected against read- and write-access.
- The firmware should be protected against external read-access.
- The verification process can be done in multiple places of the application. A tool communicating with the product, like a PC application, might carry our additional checks.
|Q:||I want to inhibit copying a whole firmware from one product hardware to another cloned one. How can I prevent it to be run from the cloned version with emSecure?|
|A:||Nearly every modern MCU includes a unique ID, which is different on every device. When the signature covers this UID it is only valid on one single device and cannot be run on a cloned or copied product. The firmware can verify the signature at boot-time.|
|Q: ||I added a digital signature to my product. Where should I verify it?|
|A:||Signature verification can be done in-product or off-product. With in-product verification the firmware for example verifies the digital signature at boot-time and refuses to run when the signature cannot be verified. With off-product verification an external application, e.g. a PC application communicating with the device, reads the signature and data from the product and verifies it.|
|Q:||I want my product to only run genuine firmware images. How can I achieve this with emSecure?|
|A:||To make sure a firmware image is genuine, the complete image can be signed with a digital signature. Like when using a CRC for integrity checks, the signature is sent with the firmware data upon a firmware update. The application or bootloader programming the firmware onto the device validates the firmware data with its signature. The signature can only be generated with the private key and should be provided by the developer with the firmware data.|
|Q:||I am providing additional licenses for my product which shall be locked to a specific user or computer. Can I generate license keys with emSecure?|
|A:||Yes. emSecure can generate unique license keys for any data, like a computer ID, a user name, e-mail address or any other data.|
|Q:||My product is sending data to a computer application. Can I make sure the computer application is getting data only from my product with emSecure?|
|A:||Yes. In this case the product is used to sign the data and the computer applications verifies it. To prevent the private key from being read from the product it might be stored encrypted on the product or in the application and decrypted prior to signing the data.|
|Q:||Does emSecure support DSA?|
|A:||No, but signing and verification code is available from SEGGER. Please get in touch with us if you feel DSA signature verification is what you need.|
|Q:||My question is not listed above. Where can I get more information?|
|A:||For more information feel free to contact us at firstname.lastname@example.org|