Cryptography in Embedded Systems
Keeping Secrets Safe Behind the Enemy Lines
When designing embedded devices, securely and efficiently adding cryptographic capabilities as identified through threat modeling is a major challenge. Also meeting cybersecurity standards and regulations can be challenging. Embedded devices face more issues than IT systems, including limited computing power due to the use of microprocessors, the requirement to resist physical attacks, and vulnerability to advanced low-level attacks targeting the hardware.
In this article, we’ll explore solutions to these challenges and highlight the best tools to address them, but first, let’s delve deeper into why these challenges are important and why cryptography in embedded systems is a very important ingredient in product security. An embedded system shall be secure even when in the hands of a malicious use. It is always to be considered “behind the enemy lines”.
Cryptography
Cryptography involves a comprehensive array of techniques including encryption, decryption, digital signatures, authentication, secure hashing, key derivation, key exchange protocols, and random number generation, all designed to secure communication, protect sensitive information, and ensure data integrity and authenticity.
Encryption: Locking Information Away
At the heart of cryptography in embedded systems lies encryption, vital for keeping sensitive data safe from unauthorized access. It scrambles data into an unreadable format (ciphertext, using an encryption key) using reversible, via decryption, cryptographic algorithms that in turn need decryption key. This ensures that even if someone gains access to the system, they can’t understand or misuse the information without the decryption key. This protects both stored and transmitted data, guarding it against interception by malicious parties.
Authentication: Verifying Identities
Cryptography is vital to verify the identity of users, devices, or processes before trusting them or them granting access to sensitive resources. Authentication mechanisms confirm the legitimacy of entities or data interacting with the system, preventing unauthorized access and potential security breaches. Techniques such as digital signatures, biometrics, or multi factor authentication help ensure that only authorized individuals or entities gain access, enhancing overall system security. Also digital signatures and other authentication techniques need secret keys to stay secret.
Key Management: safeguarding the Keys
Effective key management is essential to securely generate, store, and distribute cryptographic keys used for encryption, decryption, and authentication. Proper key management practices protect cryptographic keys from theft, loss, or unauthorized access. This involves securely storing keys, encrypting key transmission, and regularly updating keys to reduce the risk of compromise. Robust key management ensures the integrity and confidentiality of cryptographic operations, maintaining the security of hardware systems.
Challenges for Embedded Systems Security
Embedded devices, specialized for specific tasks, range from digital watches to complex automotive systems. Their inherent lack of physical security means they are fully accessible to end-users and potential adversaries. As these devices become more interconnected, managing their security becomes crucial. They handle sensitive data and control critical operations, making them targets for breaches that can lead to severe privacy, safety, financial repercussions, and the potential risk of becoming parts of botnets.
Because of this their main challenges with respect to cryptography are the following.
Performance Overhead: Resource-constrained embedded systems struggle with the computational overhead of cryptographic operations. Optimized cryptographic libraries are most of the times not enough, thus hardware accelerators address this challenge by streamlining encryption processes efficiently in hardware.
Key Management: In this context secure key storage and distribution mechanisms are difficult to get right because the attacker can potentially desolder components and modify anything on your device. Thanks to hardware-based security modules, implementing key management in embedded systems and mitigating the risk of key exposure becomes much more manageable.
Side-Channel Attacks: Embedded systems are vulnerable to side-channel attacks exploiting unintended information leakage, such as power consumption or electromagnetic emissions. Such attacks are possible also on IT systems and countermeasures like masking, shuffling, and algorithmic obfuscation enhance resistance against such attacks. But embedded systems shall withstand attacks that, for example, try to “confuse” the microprocessors by using out of spec voltages or waforms as power inputs.
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Now that we have a clear understanding about the challenges, let’s dig into the possible solutions through our next articles